Interface CachedRowSet
- All Superinterfaces:
-
AutoCloseable
,Joinable
,ResultSet
,RowSet
,Wrapper
- All Known Subinterfaces:
-
FilteredRowSet
,JoinRowSet
,WebRowSet
public interface CachedRowSet extends RowSet, Joinable
The interface that all standard implementations of CachedRowSet
must implement.
The reference implementation of the CachedRowSet
interface provided by Oracle Corporation is a standard implementation. Developers may use this implementation just as it is, they may extend it, or they may choose to write their own implementations of this interface.
A CachedRowSet
object is a container for rows of data that caches its rows in memory, which makes it possible to operate without always being connected to its data source. Further, it is a JavaBeans™ component and is scrollable, updatable, and serializable. A CachedRowSet
object typically contains rows from a result set, but it can also contain rows from any file with a tabular format, such as a spread sheet. The reference implementation supports getting data only from a ResultSet
object, but developers can extend the SyncProvider
implementations to provide access to other tabular data sources.
An application can modify the data in a CachedRowSet
object, and those modifications can then be propagated back to the source of the data.
A CachedRowSet
object is a disconnected rowset, which means that it makes use of a connection to its data source only briefly. It connects to its data source while it is reading data to populate itself with rows and again while it is propagating changes back to its underlying data source. The rest of the time, a CachedRowSet
object is disconnected, including while its data is being modified. Being disconnected makes a RowSet
object much leaner and therefore much easier to pass to another component. For example, a disconnected RowSet
object can be serialized and passed over the wire to a thin client such as a personal digital assistant (PDA).
1.0 Creating a CachedRowSet
Object
The following line of code uses the default constructor for CachedRowSet
supplied in the reference implementation (RI) to create a default CachedRowSet
object. CachedRowSetImpl crs = new CachedRowSetImpl();This new
CachedRowSet
object will have its properties set to the default properties of a BaseRowSet
object, and, in addition, it will have an RIOptimisticProvider
object as its synchronization provider. RIOptimisticProvider
, one of two SyncProvider
implementations included in the RI, is the default provider that the SyncFactory
singleton will supply when no synchronization provider is specified. A SyncProvider
object provides a CachedRowSet
object with a reader (a RowSetReader
object) for reading data from a data source to populate itself with data. A reader can be implemented to read data from a ResultSet
object or from a file with a tabular format. A SyncProvider
object also provides a writer (a RowSetWriter
object) for synchronizing any modifications to the CachedRowSet
object's data made while it was disconnected with the data in the underlying data source.
A writer can be implemented to exercise various degrees of care in checking for conflicts and in avoiding them. (A conflict occurs when a value in the data source has been changed after the rowset populated itself with that value.) The RIOptimisticProvider
implementation assumes there will be few or no conflicts and therefore sets no locks. It updates the data source with values from the CachedRowSet
object only if there are no conflicts. Other writers can be implemented so that they always write modified data to the data source, which can be accomplished either by not checking for conflicts or, on the other end of the spectrum, by setting locks sufficient to prevent data in the data source from being changed. Still other writer implementations can be somewhere in between.
A CachedRowSet
object may use any SyncProvider
implementation that has been registered with the SyncFactory
singleton. An application can find out which SyncProvider
implementations have been registered by calling the following line of code.
java.util.Enumeration providers = SyncFactory.getRegisteredProviders();
There are two ways for a CachedRowSet
object to specify which SyncProvider
object it will use.
- Supplying the name of the implementation to the constructor
The following line of code creates theCachedRowSet
object crs2 that is initialized with default values except that itsSyncProvider
object is the one specified.CachedRowSetImpl crs2 = new CachedRowSetImpl( "com.fred.providers.HighAvailabilityProvider");
- Setting the
SyncProvider
using theCachedRowSet
methodsetSyncProvider
The following line of code resets theSyncProvider
object for crs, theCachedRowSet
object created with the default constructor.crs.setSyncProvider("com.fred.providers.HighAvailabilityProvider");
SyncFactory
and SyncProvider
for more details. 2.0 Retrieving Data from a CachedRowSet
Object
Data is retrieved from a CachedRowSet
object by using the getter methods inherited from the ResultSet
interface. The following examples, in which crs
is a CachedRowSet
object, demonstrate how to iterate through the rows, retrieving the column values in each row. The first example uses the version of the getter methods that take a column number; the second example uses the version that takes a column name. Column numbers are generally used when the RowSet
object's command is of the form SELECT * FROM TABLENAME
; column names are most commonly used when the command specifies columns by name. while (crs.next()) { String name = crs.getString(1); int id = crs.getInt(2); Clob comment = crs.getClob(3); short dept = crs.getShort(4); System.out.println(name + " " + id + " " + comment + " " + dept); }
while (crs.next()) { String name = crs.getString("NAME"); int id = crs.getInt("ID"); Clob comment = crs.getClob("COM"); short dept = crs.getShort("DEPT"); System.out.println(name + " " + id + " " + comment + " " + dept); }
2.1 Retrieving RowSetMetaData
An application can get information about the columns in a CachedRowSet
object by calling ResultSetMetaData
and RowSetMetaData
methods on a RowSetMetaData
object. The following code fragment, in which crs is a CachedRowSet
object, illustrates the process. The first line creates a RowSetMetaData
object with information about the columns in crs. The method getMetaData
, inherited from the ResultSet
interface, returns a ResultSetMetaData
object, which is cast to a RowSetMetaData
object before being assigned to the variable rsmd. The second line finds out how many columns jrs has, and the third line gets the JDBC type of values stored in the second column of jrs
. RowSetMetaData rsmd = (RowSetMetaData)crs.getMetaData(); int count = rsmd.getColumnCount(); int type = rsmd.getColumnType(2);The
RowSetMetaData
interface differs from the ResultSetMetaData
interface in two ways. -
It includes
setter
methods: ARowSet
object uses these methods internally when it is populated with data from a differentResultSet
object. -
It contains fewer
getter
methods: SomeResultSetMetaData
methods to not apply to aRowSet
object. For example, methods retrieving whether a column value is writable or read only do not apply because all of aRowSet
object's columns will be writable or read only, depending on whether the rowset is updatable or not.
RowSetMetaData
object, implementations must override the getMetaData()
method defined in java.sql.ResultSet
and return a RowSetMetaData
object. 3.0 Updating a CachedRowSet
Object
Updating a CachedRowSet
object is similar to updating a ResultSet
object, but because the rowset is not connected to its data source while it is being updated, it must take an additional step to effect changes in its underlying data source. After calling the method updateRow
or insertRow
, a CachedRowSet
object must also call the method acceptChanges
to have updates written to the data source. The following example, in which the cursor is on a row in the CachedRowSet
object crs, shows the code required to update two column values in the current row and also update the RowSet
object's underlying data source. crs.updateShort(3, 58); crs.updateInt(4, 150000); crs.updateRow(); crs.acceptChanges();
The next example demonstrates moving to the insert row, building a new row on the insert row, inserting it into the rowset, and then calling the method acceptChanges
to add the new row to the underlying data source. Note that as with the getter methods, the updater methods may take either a column index or a column name to designate the column being acted upon.
crs.moveToInsertRow(); crs.updateString("Name", "Shakespeare"); crs.updateInt("ID", 10098347); crs.updateShort("Age", 58); crs.updateInt("Sal", 150000); crs.insertRow(); crs.moveToCurrentRow(); crs.acceptChanges();
NOTE: Where the insertRow()
method inserts the contents of a CachedRowSet
object's insert row is implementation-defined. The reference implementation for the CachedRowSet
interface inserts a new row immediately following the current row, but it could be implemented to insert new rows in any number of other places.
Another thing to note about these examples is how they use the method acceptChanges
. It is this method that propagates changes in a CachedRowSet
object back to the underlying data source, calling on the RowSet
object's writer internally to write changes to the data source. To do this, the writer has to incur the expense of establishing a connection with that data source. The preceding two code fragments call the method acceptChanges
immediately after calling updateRow
or insertRow
. However, when there are multiple rows being changed, it is more efficient to call acceptChanges
after all calls to updateRow
and insertRow
have been made. If acceptChanges
is called only once, only one connection needs to be established.
4.0 Updating the Underlying Data Source
When the methodacceptChanges
is executed, the CachedRowSet
object's writer, a RowSetWriterImpl
object, is called behind the scenes to write the changes made to the rowset to the underlying data source. The writer is implemented to make a connection to the data source and write updates to it. A writer is made available through an implementation of the SyncProvider
interface, as discussed in section 1, "Creating a CachedRowSet
Object." The default reference implementation provider, RIOptimisticProvider
, has its writer implemented to use an optimistic concurrency control mechanism. That is, it maintains no locks in the underlying database while the rowset is disconnected from the database and simply checks to see if there are any conflicts before writing data to the data source. If there are any conflicts, it does not write anything to the data source.
The reader/writer facility provided by the SyncProvider
class is pluggable, allowing for the customization of data retrieval and updating. If a different concurrency control mechanism is desired, a different implementation of SyncProvider
can be plugged in using the method setSyncProvider
.
In order to use the optimistic concurrency control routine, the RIOptimisticProvider
maintains both its current value and its original value (the value it had immediately preceding the current value). Note that if no changes have been made to the data in a RowSet
object, its current values and its original values are the same, both being the values with which the RowSet
object was initially populated. However, once any values in the RowSet
object have been changed, the current values and the original values will be different, though at this stage, the original values are still the initial values. With any subsequent changes to data in a RowSet
object, its original values and current values will still differ, but its original values will be the values that were previously the current values.
Keeping track of original values allows the writer to compare the RowSet
object's original value with the value in the database. If the values in the database differ from the RowSet
object's original values, which means that the values in the database have been changed, there is a conflict. Whether a writer checks for conflicts, what degree of checking it does, and how it handles conflicts all depend on how it is implemented.
5.0 Registering and Notifying Listeners
Being JavaBeans components, all rowsets participate in the JavaBeans event model, inheriting methods for registering listeners and notifying them of changes from theBaseRowSet
class. A listener for a CachedRowSet
object is a component that wants to be notified whenever there is a change in the rowset. For example, if a CachedRowSet
object contains the results of a query and those results are being displayed in, say, a table and a bar graph, the table and bar graph could be registered as listeners with the rowset so that they can update themselves to reflect changes. To become listeners, the table and bar graph classes must implement the RowSetListener
interface. Then they can be added to the CachedRowSet
object's list of listeners, as is illustrated in the following lines of code. crs.addRowSetListener(table); crs.addRowSetListener(barGraph);Each
CachedRowSet
method that moves the cursor or changes data also notifies registered listeners of the changes, so table
and barGraph
will be notified when there is a change in crs
. 6.0 Passing Data to Thin Clients
One of the main reasons to use aCachedRowSet
object is to pass data between different components of an application. Because it is serializable, a CachedRowSet
object can be used, for example, to send the result of a query executed by an enterprise JavaBeans component running in a server environment over a network to a client running in a web browser. While a CachedRowSet
object is disconnected, it can be much leaner than a ResultSet
object with the same data. As a result, it can be especially suitable for sending data to a thin client such as a PDA, where it would be inappropriate to use a JDBC driver due to resource limitations or security considerations. Thus, a CachedRowSet
object provides a means to "get rows in" without the need to implement the full JDBC API.
7.0 Scrolling and Updating
A second major use forCachedRowSet
objects is to provide scrolling and updating for ResultSet
objects that do not provide these capabilities themselves. In other words, a CachedRowSet
object can be used to augment the capabilities of a JDBC technology-enabled driver (hereafter called a "JDBC driver") when the DBMS does not provide full support for scrolling and updating. To achieve the effect of making a non-scrollable and read-only ResultSet
object scrollable and updatable, a programmer simply needs to create a CachedRowSet
object populated with that ResultSet
object's data. This is demonstrated in the following code fragment, where stmt
is a Statement
object. ResultSet rs = stmt.executeQuery("SELECT * FROM EMPLOYEES"); CachedRowSetImpl crs = new CachedRowSetImpl(); crs.populate(rs);
The object crs
now contains the data from the table EMPLOYEES
, just as the object rs
does. The difference is that the cursor for crs
can be moved forward, backward, or to a particular row even if the cursor for rs
can move only forward. In addition, crs
is updatable even if rs
is not because by default, a CachedRowSet
object is both scrollable and updatable.
In summary, a CachedRowSet
object can be thought of as simply a disconnected set of rows that are being cached outside of a data source. Being thin and serializable, it can easily be sent across a wire, and it is well suited to sending data to a thin client. However, a CachedRowSet
object does have a limitation: It is limited in size by the amount of data it can store in memory at one time.
8.0 Getting Universal Data Access
Another advantage of theCachedRowSet
class is that it makes it possible to retrieve and store data from sources other than a relational database. The reader for a rowset can be implemented to read and populate its rowset with data from any tabular data source, including a spreadsheet or flat file. Because both a CachedRowSet
object and its metadata can be created from scratch, a component that acts as a factory for rowsets can use this capability to create a rowset containing data from non-SQL data sources. Nevertheless, it is expected that most of the time, CachedRowSet
objects will contain data that was fetched from an SQL database using the JDBC API. 9.0 Setting Properties
All rowsets maintain a set of properties, which will usually be set using a tool. The number and kinds of properties a rowset has will vary, depending on what the rowset does and how it gets its data. For example, rowsets that get their data from aResultSet
object need to set the properties that are required for making a database connection. If a rowset uses the DriverManager
facility to make a connection, it needs to set a property for the JDBC URL that identifies the appropriate driver, and it needs to set the properties that give the user name and password. If, on the other hand, the rowset uses a DataSource
object to make the connection, which is the preferred method, it does not need to set the property for the JDBC URL. Instead, it needs to set properties for the logical name of the data source, for the user name, and for the password. NOTE: In order to use a DataSource
object for making a connection, the DataSource
object must have been registered with a naming service that uses the Java Naming and Directory Interface™ (JNDI) API. This registration is usually done by a person acting in the capacity of a system administrator.
In order to be able to populate itself with data from a database, a rowset needs to set a command property. This property is a query that is a PreparedStatement
object, which allows the query to have parameter placeholders that are set at run time, as opposed to design time. To set these placeholder parameters with values, a rowset provides setter methods for setting values of each data type, similar to the setter methods provided by the PreparedStatement
interface.
The following code fragment illustrates how the CachedRowSet
object crs
might have its command property set. Note that if a tool is used to set properties, this is the code that the tool would use.
crs.setCommand("SELECT FIRST_NAME, LAST_NAME, ADDRESS FROM CUSTOMERS " + "WHERE CREDIT_LIMIT > ? AND REGION = ?");
The values that will be used to set the command's placeholder parameters are contained in the RowSet
object's params
field, which is a Vector
object. The CachedRowSet
class provides a set of setter methods for setting the elements in its params
field. The following code fragment demonstrates setting the two parameters in the query from the previous example.
crs.setInt(1, 5000); crs.setString(2, "West");
The params
field now contains two elements, each of which is an array two elements long. The first element is the parameter number; the second is the value to be set. In this case, the first element of params
is 1
, 5000
, and the second element is 2
, "West"
. When an application calls the method execute
, it will in turn call on this RowSet
object's reader, which will in turn invoke its readData
method. As part of its implementation, readData
will get the values in params
and use them to set the command's placeholder parameters. The following code fragment gives an idea of how the reader does this, after obtaining the Connection
object con
.
PreparedStatement pstmt = con.prepareStatement(crs.getCommand()); reader.decodeParams(); // decodeParams figures out which setter methods to use and does something // like the following: // for (i = 0; i < params.length; i++) { // pstmt.setObject(i + 1, params[i]); // }
At this point, the command for crs
is the query "SELECT
FIRST_NAME, LAST_NAME, ADDRESS FROM CUSTOMERS WHERE CREDIT_LIMIT > 5000
AND REGION = "West"
. After the readData
method executes this command with the following line of code, it will have the data from rs
with which to populate crs
.
ResultSet rs = pstmt.executeQuery();
The preceding code fragments give an idea of what goes on behind the scenes; they would not appear in an application, which would not invoke methods like readData
and decodeParams
. In contrast, the following code fragment shows what an application might do. It sets the rowset's command, sets the command's parameters, and executes the command. Simply by calling the execute
method, crs
populates itself with the requested data from the table CUSTOMERS
.
crs.setCommand("SELECT FIRST_NAME, LAST_NAME, ADDRESS FROM CUSTOMERS" + "WHERE CREDIT_LIMIT > ? AND REGION = ?"); crs.setInt(1, 5000); crs.setString(2, "West"); crs.execute();
10.0 Paging Data
Because aCachedRowSet
object stores data in memory, the amount of data that it can contain at any one time is determined by the amount of memory available. To get around this limitation, a CachedRowSet
object can retrieve data from a ResultSet
object in chunks of data, called pages. To take advantage of this mechanism, an application sets the number of rows to be included in a page using the method setPageSize
. In other words, if the page size is set to five, a chunk of five rows of data will be fetched from the data source at one time. An application can also optionally set the maximum number of rows that may be fetched at one time. If the maximum number of rows is set to zero, or no maximum number of rows is set, there is no limit to the number of rows that may be fetched at a time. After properties have been set, the CachedRowSet
object must be populated with data using either the method populate
or the method execute
. The following lines of code demonstrate using the method populate
. Note that this version of the method takes two parameters, a ResultSet
handle and the row in the ResultSet
object from which to start retrieving rows.
CachedRowSet crs = new CachedRowSetImpl(); crs.setMaxRows(20); crs.setPageSize(4); crs.populate(rsHandle, 10);When this code runs, crs will be populated with four rows from rsHandle starting with the tenth row.
The next code fragment shows populating a CachedRowSet
object using the method execute
, which may or may not take a Connection
object as a parameter. This code passes execute
the Connection
object conHandle.
Note that there are two differences between the following code fragment and the previous one. First, the method setMaxRows
is not called, so there is no limit set for the number of rows that crs may contain. (Remember that crs always has the overriding limit of how much data it can store in memory.) The second difference is that the you cannot pass the method execute
the number of the row in the ResultSet
object from which to start retrieving rows. This method always starts with the first row.
CachedRowSet crs = new CachedRowSetImpl(); crs.setPageSize(5); crs.execute(conHandle);After this code has run, crs will contain five rows of data from the
ResultSet
object produced by the command for crs. The writer for crs will use conHandle to connect to the data source and execute the command for crs. An application is then able to operate on the data in crs in the same way that it would operate on data in any other CachedRowSet
object. To access the next page (chunk of data), an application calls the method nextPage
. This method creates a new CachedRowSet
object and fills it with the next page of data. For example, assume that the CachedRowSet
object's command returns a ResultSet
object rs with 1000 rows of data. If the page size has been set to 100, the first call to the method nextPage
will create a CachedRowSet
object containing the first 100 rows of rs. After doing what it needs to do with the data in these first 100 rows, the application can again call the method nextPage
to create another CachedRowSet
object with the second 100 rows from rs. The data from the first CachedRowSet
object will no longer be in memory because it is replaced with the data from the second CachedRowSet
object. After the tenth call to the method nextPage
, the tenth CachedRowSet
object will contain the last 100 rows of data from rs, which are stored in memory. At any given time, the data from only one CachedRowSet
object is stored in memory.
The method nextPage
returns true
as long as the current page is not the last page of rows and false
when there are no more pages. It can therefore be used in a while
loop to retrieve all of the pages, as is demonstrated in the following lines of code.
CachedRowSet crs = CachedRowSetImpl(); crs.setPageSize(100); crs.execute(conHandle); while(crs.nextPage()) { while(crs.next()) { . . . // operate on chunks (of 100 rows each) in crs, // row by row } }After this code fragment has been run, the application will have traversed all 1000 rows, but it will have had no more than 100 rows in memory at a time.
The CachedRowSet
interface also defines the method previousPage
. Just as the method nextPage
is analogous to the ResultSet
method next
, the method previousPage
is analogous to the ResultSet
method previous
. Similar to the method nextPage
, previousPage
creates a CachedRowSet
object containing the number of rows set as the page size. So, for instance, the method previousPage
could be used in a while
loop at the end of the preceding code fragment to navigate back through the pages from the last page to the first page. The method previousPage
is also similar to nextPage
in that it can be used in a while
loop, except that it returns true
as long as there is another page preceding it and false
when there are no more pages ahead of it.
By positioning the cursor after the last row for each page, as is done in the following code fragment, the method previous
navigates from the last row to the first row in each page. The code could also have left the cursor before the first row on each page and then used the method next
in a while
loop to navigate each page from the first row to the last row.
The following code fragment assumes a continuation from the previous code fragment, meaning that the cursor for the tenth CachedRowSet
object is on the last row. The code moves the cursor to after the last row so that the first call to the method previous
will put the cursor back on the last row. After going through all of the rows in the last page (the CachedRowSet
object crs), the code then enters the while
loop to get to the ninth page, go through the rows backwards, go to the eighth page, go through the rows backwards, and so on to the first row of the first page.
crs.afterLast(); while(crs.previous()) { . . . // navigate through the rows, last to first { while(crs.previousPage()) { crs.afterLast(); while(crs.previous()) { . . . // go from the last row to the first row of each page } }
- Since:
- 1.5
Field Summary
Modifier and Type | Field | Description |
---|---|---|
static boolean | COMMIT_ON_ACCEPT_CHANGES | Deprecated. Because this field is final (it is part of an interface), its value cannot be changed. |
Fields declared in interface java.sql.ResultSet
CLOSE_CURSORS_AT_COMMIT, CONCUR_READ_ONLY, CONCUR_UPDATABLE, FETCH_FORWARD, FETCH_REVERSE, FETCH_UNKNOWN, HOLD_CURSORS_OVER_COMMIT, TYPE_FORWARD_ONLY, TYPE_SCROLL_INSENSITIVE, TYPE_SCROLL_SENSITIVE
Method Summary
Modifier and Type | Method | Description |
---|---|---|
void | acceptChanges() | Propagates row update, insert and delete changes made to this |
void | acceptChanges(Connection con) | Propagates all row update, insert and delete changes to the data source backing this |
boolean | columnUpdated(int idx) | Indicates whether the designated column in the current row of this |
boolean | columnUpdated(String columnName) | Indicates whether the designated column in the current row of this |
void | commit() | Each |
CachedRowSet | createCopy() | Creates a |
CachedRowSet | createCopyNoConstraints() | Creates a |
CachedRowSet | createCopySchema() | Creates a |
RowSet | createShared() | Returns a new |
void | execute(Connection conn) | Populates this |
int[] | getKeyColumns() | Returns an array containing one or more column numbers indicating the columns that form a key that uniquely identifies a row in this |
ResultSet | getOriginal() | Returns a |
ResultSet | getOriginalRow() | Returns a |
int | getPageSize() | Returns the page-size for the |
RowSetWarning | getRowSetWarnings() | Retrieves the first warning reported by calls on this |
boolean | getShowDeleted() | Retrieves a |
SyncProvider | getSyncProvider() | Retrieves the |
String | getTableName() | Returns an identifier for the object (table) that was used to create this |
boolean | nextPage() | Increments the current page of the |
void | populate(ResultSet data) | Populates this |
void | populate(ResultSet rs,
int startRow) | Populates this |
boolean | previousPage() | Decrements the current page of the |
void | release() | Releases the current contents of this |
void | restoreOriginal() | Restores this |
void | rollback() | Each |
void | rollback(Savepoint s) | Each |
void | rowSetPopulated(RowSetEvent event,
int numRows) | Notifies registered listeners that a RowSet object in the given RowSetEvent object has populated a number of additional rows. |
void | setKeyColumns(int[] keys) | Sets this |
void | setMetaData(RowSetMetaData md) | Sets the metadata for this |
void | setOriginalRow() | Sets the current row in this |
void | setPageSize(int size) | Sets the |
void | setShowDeleted(boolean b) | Sets the property |
void | setSyncProvider(String provider) | Sets the |
void | setTableName(String tabName) | Sets the identifier for the table from which this |
int | size() | Returns the number of rows in this |
Collection<?> | toCollection() | Converts this |
Collection<?> | toCollection(int column) | Converts the designated column in this |
Collection<?> | toCollection(String column) | Converts the designated column in this |
void | undoDelete() | Cancels the deletion of the current row and notifies listeners that a row has changed. |
void | undoInsert() | Immediately removes the current row from this |
void | undoUpdate() | Immediately reverses the last update operation if the row has been modified. |
Methods declared in interface javax.sql.rowset.Joinable
getMatchColumnIndexes, getMatchColumnNames, setMatchColumn, setMatchColumn, setMatchColumn, setMatchColumn, unsetMatchColumn, unsetMatchColumn, unsetMatchColumn, unsetMatchColumn
Methods declared in interface java.sql.ResultSet
absolute, afterLast, beforeFirst, cancelRowUpdates, clearWarnings, close, deleteRow, findColumn, first, getArray, getArray, getAsciiStream, getAsciiStream, getBigDecimal, getBigDecimal, getBigDecimal, getBigDecimal, getBinaryStream, getBinaryStream, getBlob, getBlob, getBoolean, getBoolean, getByte, getByte, getBytes, getBytes, getCharacterStream, getCharacterStream, getClob, getClob, getConcurrency, getCursorName, getDate, getDate, getDate, getDate, getDouble, getDouble, getFetchDirection, getFetchSize, getFloat, getFloat, getHoldability, getInt, getInt, getLong, getLong, getMetaData, getNCharacterStream, getNCharacterStream, getNClob, getNClob, getNString, getNString, getObject, getObject, getObject, getObject, getObject, getObject, getRef, getRef, getRow, getRowId, getRowId, getShort, getShort, getSQLXML, getSQLXML, getStatement, getString, getString, getTime, getTime, getTime, getTime, getTimestamp, getTimestamp, getTimestamp, getTimestamp, getType, getUnicodeStream, getUnicodeStream, getURL, getURL, getWarnings, insertRow, isAfterLast, isBeforeFirst, isClosed, isFirst, isLast, last, moveToCurrentRow, moveToInsertRow, next, previous, refreshRow, relative, rowDeleted, rowInserted, rowUpdated, setFetchDirection, setFetchSize, updateArray, updateArray, updateAsciiStream, updateAsciiStream, updateAsciiStream, updateAsciiStream, updateAsciiStream, updateAsciiStream, updateBigDecimal, updateBigDecimal, updateBinaryStream, updateBinaryStream, updateBinaryStream, updateBinaryStream, updateBinaryStream, updateBinaryStream, updateBlob, updateBlob, updateBlob, updateBlob, updateBlob, updateBlob, updateBoolean, updateBoolean, updateByte, updateByte, updateBytes, updateBytes, updateCharacterStream, updateCharacterStream, updateCharacterStream, updateCharacterStream, updateCharacterStream, updateCharacterStream, updateClob, updateClob, updateClob, updateClob, updateClob, updateClob, updateDate, updateDate, updateDouble, updateDouble, updateFloat, updateFloat, updateInt, updateInt, updateLong, updateLong, updateNCharacterStream, updateNCharacterStream, updateNCharacterStream, updateNCharacterStream, updateNClob, updateNClob, updateNClob, updateNClob, updateNClob, updateNClob, updateNString, updateNString, updateNull, updateNull, updateObject, updateObject, updateObject, updateObject, updateObject, updateObject, updateObject, updateObject, updateRef, updateRef, updateRow, updateRowId, updateRowId, updateShort, updateShort, updateSQLXML, updateSQLXML, updateString, updateString, updateTime, updateTime, updateTimestamp, updateTimestamp, wasNull
Methods declared in interface javax.sql.RowSet
addRowSetListener, clearParameters, execute, getCommand, getDataSourceName, getEscapeProcessing, getMaxFieldSize, getMaxRows, getPassword, getQueryTimeout, getTransactionIsolation, getTypeMap, getUrl, getUsername, isReadOnly, removeRowSetListener, setArray, setAsciiStream, setAsciiStream, setAsciiStream, setAsciiStream, setBigDecimal, setBigDecimal, setBinaryStream, setBinaryStream, setBinaryStream, setBinaryStream, setBlob, setBlob, setBlob, setBlob, setBlob, setBlob, setBoolean, setBoolean, setByte, setByte, setBytes, setBytes, setCharacterStream, setCharacterStream, setCharacterStream, setCharacterStream, setClob, setClob, setClob, setClob, setClob, setClob, setCommand, setConcurrency, setDataSourceName, setDate, setDate, setDate, setDate, setDouble, setDouble, setEscapeProcessing, setFloat, setFloat, setInt, setInt, setLong, setLong, setMaxFieldSize, setMaxRows, setNCharacterStream, setNCharacterStream, setNCharacterStream, setNCharacterStream, setNClob, setNClob, setNClob, setNClob, setNClob, setNClob, setNString, setNString, setNull, setNull, setNull, setNull, setObject, setObject, setObject, setObject, setObject, setObject, setPassword, setQueryTimeout, setReadOnly, setRef, setRowId, setRowId, setShort, setShort, setSQLXML, setSQLXML, setString, setString, setTime, setTime, setTime, setTime, setTimestamp, setTimestamp, setTimestamp, setTimestamp, setTransactionIsolation, setType, setTypeMap, setUrl, setURL, setUsername
Methods declared in interface java.sql.Wrapper
isWrapperFor, unwrap
Field Detail
COMMIT_ON_ACCEPT_CHANGES
@Deprecated static final boolean COMMIT_ON_ACCEPT_CHANGES
Causes the CachedRowSet
object's SyncProvider
to commit the changes when acceptChanges()
is called. If set to false, the changes will not be committed until one of the CachedRowSet
interface transaction methods is called.
- See Also:
-
commit()
,rollback()
, Constant Field Values
Method Detail
populate
void populate(ResultSet data) throws SQLException
Populates this CachedRowSet
object with data from the given ResultSet
object.
This method can be used as an alternative to the execute
method when an application has a connection to an open ResultSet
object. Using the method populate
can be more efficient than using the version of the execute
method that takes no parameters because it does not open a new connection and re-execute this CachedRowSet
object's command. Using the populate
method is more a matter of convenience when compared to using the version of execute
that takes a ResultSet
object.
- Parameters:
-
data
- theResultSet
object containing the data to be read into thisCachedRowSet
object - Throws:
-
SQLException
- if a nullResultSet
object is supplied or thisCachedRowSet
object cannot retrieve the associatedResultSetMetaData
object - See Also:
-
execute(java.sql.Connection)
,ResultSet
,ResultSetMetaData
execute
void execute(Connection conn) throws SQLException
Populates this CachedRowSet
object with data, using the given connection to produce the result set from which the data will be read. This method should close any database connections that it creates to ensure that this CachedRowSet
object is disconnected except when it is reading data from its data source or writing data to its data source.
The reader for this CachedRowSet
object will use conn to establish a connection to the data source so that it can execute the rowset's command and read data from the the resulting ResultSet
object into this CachedRowSet
object. This method also closes conn after it has populated this CachedRowSet
object.
If this method is called when an implementation has already been populated, the contents and the metadata are (re)set. Also, if this method is called before the method acceptChanges
has been called to commit outstanding updates, those updates are lost.
- Parameters:
-
conn
- a standard JDBCConnection
object with valid properties - Throws:
-
SQLException
- if an invalidConnection
object is supplied or an error occurs in establishing the connection to the data source - See Also:
-
populate(java.sql.ResultSet)
,Connection
acceptChanges
void acceptChanges() throws SyncProviderException
Propagates row update, insert and delete changes made to this CachedRowSet
object to the underlying data source.
This method calls on this CachedRowSet
object's writer to do the work behind the scenes. Standard CachedRowSet
implementations should use the SyncFactory
singleton to obtain a SyncProvider
instance providing a RowSetWriter
object (writer). The writer will attempt to propagate changes made in this CachedRowSet
object back to the data source.
When the method acceptChanges
executes successfully, in addition to writing changes to the data source, it makes the values in the current row be the values in the original row.
Depending on the synchronization level of the SyncProvider
implementation being used, the writer will compare the original values with those in the data source to check for conflicts. When there is a conflict, the RIOptimisticProvider
implementation, for example, throws a SyncProviderException
and does not write anything to the data source.
An application may choose to catch the SyncProviderException
object and retrieve the SyncResolver
object it contains. The SyncResolver
object lists the conflicts row by row and sets a lock on the data source to avoid further conflicts while the current conflicts are being resolved. Further, for each conflict, it provides methods for examining the conflict and setting the value that should be persisted in the data source. After all conflicts have been resolved, an application must call the acceptChanges
method again to write resolved values to the data source. If all of the values in the data source are already the values to be persisted, the method acceptChanges
does nothing.
Some provider implementations may use locks to ensure that there are no conflicts. In such cases, it is guaranteed that the writer will succeed in writing changes to the data source when the method acceptChanges
is called. This method may be called immediately after the methods updateRow
, insertRow
, or deleteRow
have been called, but it is more efficient to call it only once after all changes have been made so that only one connection needs to be established.
Note: The acceptChanges()
method will determine if the COMMIT_ON_ACCEPT_CHANGES
is set to true or not. If it is set to true, all updates in the synchronization are committed to the data source. Otherwise, the application must explicitly call the commit()
or rollback()
methods as appropriate.
- Throws:
-
SyncProviderException
- if the underlying synchronization provider's writer fails to write the updates back to the data source - See Also:
-
acceptChanges(java.sql.Connection)
,RowSetWriter
,SyncFactory
,SyncProvider
,SyncProviderException
,SyncResolver
acceptChanges
void acceptChanges(Connection con) throws SyncProviderException
Propagates all row update, insert and delete changes to the data source backing this CachedRowSet
object using the specified Connection
object to establish a connection to the data source.
The other version of the acceptChanges
method is not passed a connection because it uses the Connection
object already defined within the RowSet
object, which is the connection used for populating it initially.
This form of the method acceptChanges
is similar to the form that takes no arguments; however, unlike the other form, this form can be used only when the underlying data source is a JDBC data source. The updated Connection
properties must be used by the SyncProvider
to reset the RowSetWriter
configuration to ensure that the contents of the CachedRowSet
object are synchronized correctly.
When the method acceptChanges
executes successfully, in addition to writing changes to the data source, it makes the values in the current row be the values in the original row.
Depending on the synchronization level of the SyncProvider
implementation being used, the writer will compare the original values with those in the data source to check for conflicts. When there is a conflict, the RIOptimisticProvider
implementation, for example, throws a SyncProviderException
and does not write anything to the data source.
An application may choose to catch the SyncProviderException
object and retrieve the SyncResolver
object it contains. The SyncResolver
object lists the conflicts row by row and sets a lock on the data source to avoid further conflicts while the current conflicts are being resolved. Further, for each conflict, it provides methods for examining the conflict and setting the value that should be persisted in the data source. After all conflicts have been resolved, an application must call the acceptChanges
method again to write resolved values to the data source. If all of the values in the data source are already the values to be persisted, the method acceptChanges
does nothing.
Some provider implementations may use locks to ensure that there are no conflicts. In such cases, it is guaranteed that the writer will succeed in writing changes to the data source when the method acceptChanges
is called. This method may be called immediately after the methods updateRow
, insertRow
, or deleteRow
have been called, but it is more efficient to call it only once after all changes have been made so that only one connection needs to be established.
Note: The acceptChanges()
method will determine if the COMMIT_ON_ACCEPT_CHANGES
is set to true or not. If it is set to true, all updates in the synchronization are committed to the data source. Otherwise, the application must explicitly call the commit
or rollback
methods as appropriate.
- Parameters:
-
con
- a standard JDBCConnection
object - Throws:
-
SyncProviderException
- if the underlying synchronization provider's writer fails to write the updates back to the data source - See Also:
-
acceptChanges()
,RowSetWriter
,SyncFactory
,SyncProvider
,SyncProviderException
,SyncResolver
restoreOriginal
void restoreOriginal() throws SQLException
Restores this CachedRowSet
object to its original value, that is, its value before the last set of changes. If there have been no changes to the rowset or only one set of changes, the original value is the value with which this CachedRowSet
object was populated; otherwise, the original value is the value it had immediately before its current value.
When this method is called, a CachedRowSet
implementation must ensure that all updates, inserts, and deletes to the current rowset instance are replaced by the previous values. In addition, the cursor should be reset to the first row and a rowSetChanged
event should be fired to notify all registered listeners.
- Throws:
-
SQLException
- if an error occurs rolling back the current value of thisCachedRowSet
object to its previous value - See Also:
RowSetListener.rowSetChanged(javax.sql.RowSetEvent)
release
void release() throws SQLException
Releases the current contents of this CachedRowSet
object and sends a rowSetChanged
event to all registered listeners. Any outstanding updates are discarded and the rowset contains no rows after this method is called. There are no interactions with the underlying data source, and any rowset content, metadata, and content updates should be non-recoverable.
This CachedRowSet
object should lock until its contents and associated updates are fully cleared, thus preventing 'dirty' reads by other components that hold a reference to this RowSet
object. In addition, the contents cannot be released until all components reading this CachedRowSet
object have completed their reads. This CachedRowSet
object should be returned to normal behavior after firing the rowSetChanged
event.
The metadata, including JDBC properties and Synchronization SPI properties, are maintained for future use. It is important that properties such as the command
property be relevant to the originating data source from which this CachedRowSet
object was originally established.
This method empties a rowset, as opposed to the close
method, which marks the entire rowset as recoverable to allow the garbage collector the rowset's Java VM resources.
- Throws:
-
SQLException
- if an error occurs flushing the contents of thisCachedRowSet
object - See Also:
-
RowSetListener.rowSetChanged(javax.sql.RowSetEvent)
,ResultSet.close()
undoDelete
void undoDelete() throws SQLException
Cancels the deletion of the current row and notifies listeners that a row has changed. After this method is called, the current row is no longer marked for deletion. This method can be called at any time during the lifetime of the rowset.
In addition, multiple cancellations of row deletions can be made by adjusting the position of the cursor using any of the cursor position control methods such as:
-
CachedRowSet.absolute
-
CachedRowSet.first
-
CachedRowSet.last
- Throws:
-
SQLException
- if (1) the current row has not been deleted or (2) the cursor is on the insert row, before the first row, or after the last row - See Also:
-
undoInsert()
,ResultSet.cancelRowUpdates()
undoInsert
void undoInsert() throws SQLException
Immediately removes the current row from this CachedRowSet
object if the row has been inserted, and also notifies listeners that a row has changed. This method can be called at any time during the lifetime of a rowset and assuming the current row is within the exception limitations (see below), it cancels the row insertion of the current row.
In addition, multiple cancellations of row insertions can be made by adjusting the position of the cursor using any of the cursor position control methods such as:
-
CachedRowSet.absolute
-
CachedRowSet.first
-
CachedRowSet.last
- Throws:
-
SQLException
- if (1) the current row has not been inserted or (2) the cursor is before the first row, after the last row, or on the insert row - See Also:
-
undoDelete()
,ResultSet.cancelRowUpdates()
undoUpdate
void undoUpdate() throws SQLException
Immediately reverses the last update operation if the row has been modified. This method can be called to reverse updates on all columns until all updates in a row have been rolled back to their state just prior to the last synchronization (acceptChanges
) or population. This method may also be called while performing updates to the insert row.
undoUpdate
may be called at any time during the lifetime of a rowset; however, after a synchronization has occurred, this method has no effect until further modification to the rowset data has occurred.
- Throws:
-
SQLException
- if the cursor is before the first row or after the last row in thisCachedRowSet
object - See Also:
-
undoDelete()
,undoInsert()
,ResultSet.cancelRowUpdates()
columnUpdated
boolean columnUpdated(int idx) throws SQLException
Indicates whether the designated column in the current row of this CachedRowSet
object has been updated.
- Parameters:
-
idx
- anint
identifying the column to be checked for updates - Returns:
-
true
if the designated column has been visibly updated;false
otherwise - Throws:
-
SQLException
- if the cursor is on the insert row, before the first row, or after the last row - See Also:
DatabaseMetaData.updatesAreDetected(int)
columnUpdated
boolean columnUpdated(String columnName) throws SQLException
Indicates whether the designated column in the current row of this CachedRowSet
object has been updated.
- Parameters:
-
columnName
- aString
object giving the name of the column to be checked for updates - Returns:
-
true
if the column has been visibly updated;false
otherwise - Throws:
-
SQLException
- if the cursor is on the insert row, before the first row, or after the last row - See Also:
DatabaseMetaData.updatesAreDetected(int)
toCollection
Collection<?> toCollection() throws SQLException
Converts this CachedRowSet
object to a Collection
object that contains all of this CachedRowSet
object's data. Implementations have some latitude in how they can represent this Collection
object because of the abstract nature of the Collection
framework. Each row must be fully represented in either a general purpose Collection
implementation or a specialized Collection
implementation, such as a TreeMap
object or a Vector
object. An SQL NULL
column value must be represented as a null
in the Java programming language.
The standard reference implementation for the CachedRowSet
interface uses a TreeMap
object for the rowset, with the values in each row being contained in Vector
objects. It is expected that most implementations will do the same.
The TreeMap
type of collection guarantees that the map will be in ascending key order, sorted according to the natural order for the key's class. Each key references a Vector
object that corresponds to one row of a RowSet
object. Therefore, the size of each Vector
object must be exactly equal to the number of columns in the RowSet
object. The key used by the TreeMap
collection is determined by the implementation, which may choose to leverage a set key that is available within the internal RowSet
tabular structure by virtue of a key already set either on the RowSet
object itself or on the underlying SQL data.
- Returns:
- a
Collection
object that contains the values in each row in thisCachedRowSet
object - Throws:
-
SQLException
- if an error occurs generating the collection - See Also:
-
toCollection(int)
,toCollection(String)
toCollection
Collection<?> toCollection(int column) throws SQLException
Converts the designated column in this CachedRowSet
object to a Collection
object. Implementations have some latitude in how they can represent this Collection
object because of the abstract nature of the Collection
framework. Each column value should be fully represented in either a general purpose Collection
implementation or a specialized Collection
implementation, such as a Vector
object. An SQL NULL
column value must be represented as a null
in the Java programming language.
The standard reference implementation uses a Vector
object to contain the column values, and it is expected that most implementations will do the same. If a Vector
object is used, it size must be exactly equal to the number of rows in this CachedRowSet
object.
- Parameters:
-
column
- anint
indicating the column whose values are to be represented in aCollection
object - Returns:
- a
Collection
object that contains the values stored in the specified column of thisCachedRowSet
object - Throws:
-
SQLException
- if an error occurs generating the collection or an invalid column id is provided - See Also:
-
toCollection()
,toCollection(String)
toCollection
Collection<?> toCollection(String column) throws SQLException
Converts the designated column in this CachedRowSet
object to a Collection
object. Implementations have some latitude in how they can represent this Collection
object because of the abstract nature of the Collection
framework. Each column value should be fully represented in either a general purpose Collection
implementation or a specialized Collection
implementation, such as a Vector
object. An SQL NULL
column value must be represented as a null
in the Java programming language.
The standard reference implementation uses a Vector
object to contain the column values, and it is expected that most implementations will do the same. If a Vector
object is used, it size must be exactly equal to the number of rows in this CachedRowSet
object.
- Parameters:
-
column
- aString
object giving the name of the column whose values are to be represented in a collection - Returns:
- a
Collection
object that contains the values stored in the specified column of thisCachedRowSet
object - Throws:
-
SQLException
- if an error occurs generating the collection or an invalid column id is provided - See Also:
-
toCollection()
,toCollection(int)
getSyncProvider
SyncProvider getSyncProvider() throws SQLException
Retrieves the SyncProvider
implementation for this CachedRowSet
object. Internally, this method is used by a rowset to trigger read or write actions between the rowset and the data source. For example, a rowset may need to get a handle on the rowset reader (RowSetReader
object) from the SyncProvider
to allow the rowset to be populated.
RowSetReader rowsetReader = null; SyncProvider provider = SyncFactory.getInstance("javax.sql.rowset.provider.RIOptimisticProvider"); if (provider instanceof RIOptimisticProvider) { rowsetReader = provider.getRowSetReader(); }Assuming rowsetReader is a private, accessible field within the rowset implementation, when an application calls the
execute
method, it in turn calls on the reader's readData
method to populate the RowSet
object. rowsetReader.readData((RowSetInternal)this);
In addition, an application can use the SyncProvider
object returned by this method to call methods that return information about the SyncProvider
object, including information about the vendor, version, provider identification, synchronization grade, and locks it currently has set.
- Returns:
- the
SyncProvider
object that was set when the rowset was instantiated, or if none was set, the default provider - Throws:
-
SQLException
- if an error occurs while returning theSyncProvider
object - See Also:
setSyncProvider(java.lang.String)
setSyncProvider
void setSyncProvider(String provider) throws SQLException
Sets the SyncProvider
object for this CachedRowSet
object to the one specified. This method allows the SyncProvider
object to be reset.
A CachedRowSet
implementation should always be instantiated with an available SyncProvider
mechanism, but there are cases where resetting the SyncProvider
object is desirable or necessary. For example, an application might want to use the default SyncProvider
object for a time and then choose to use a provider that has more recently become available and better fits its needs.
Resetting the SyncProvider
object causes the RowSet
object to request a new SyncProvider
implementation from the SyncFactory
. This has the effect of resetting all previous connections and relationships with the originating data source and can potentially drastically change the synchronization behavior of a disconnected rowset.
- Parameters:
-
provider
- aString
object giving the fully qualified class name of aSyncProvider
implementation - Throws:
-
SQLException
- if an error occurs while attempting to reset theSyncProvider
implementation - See Also:
getSyncProvider()
size
int size()
Returns the number of rows in this CachedRowSet
object.
- Returns:
- number of rows in the rowset
setMetaData
void setMetaData(RowSetMetaData md) throws SQLException
Sets the metadata for this CachedRowSet
object with the given RowSetMetaData
object. When a RowSetReader
object is reading the contents of a rowset, it creates a RowSetMetaData
object and initializes it using the methods in the RowSetMetaData
implementation. The reference implementation uses the RowSetMetaDataImpl
class. When the reader has completed reading the rowset contents, this method is called internally to pass the RowSetMetaData
object to the rowset.
- Parameters:
-
md
- aRowSetMetaData
object containing metadata about the columns in thisCachedRowSet
object - Throws:
-
SQLException
- if invalid metadata is supplied to the rowset
getOriginal
ResultSet getOriginal() throws SQLException
Returns a ResultSet
object containing the original value of this CachedRowSet
object.
The cursor for the ResultSet
object should be positioned before the first row. In addition, the returned ResultSet
object should have the following properties:
- ResultSet.TYPE_SCROLL_INSENSITIVE
- ResultSet.CONCUR_UPDATABLE
The original value for a RowSet
object is the value it had before the last synchronization with the underlying data source. If there have been no synchronizations, the original value will be the value with which the RowSet
object was populated. This method is called internally when an application calls the method acceptChanges
and the SyncProvider
object has been implemented to check for conflicts. If this is the case, the writer compares the original value with the value currently in the data source to check for conflicts.
- Returns:
- a
ResultSet
object that contains the original value for thisCachedRowSet
object - Throws:
-
SQLException
- if an error occurs producing theResultSet
object
getOriginalRow
ResultSet getOriginalRow() throws SQLException
Returns a ResultSet
object containing the original value for the current row only of this CachedRowSet
object.
The cursor for the ResultSet
object should be positioned before the first row. In addition, the returned ResultSet
object should have the following properties:
- ResultSet.TYPE_SCROLL_INSENSITIVE
- ResultSet.CONCUR_UPDATABLE
- Returns:
- the original result set of the row
- Throws:
-
SQLException
- if there is no current row - See Also:
setOriginalRow()
setOriginalRow
void setOriginalRow() throws SQLException
Sets the current row in this CachedRowSet
object as the original row.
This method is called internally after the any modified values in the current row have been synchronized with the data source. The current row must be tagged as no longer inserted, deleted or updated.
A call to setOriginalRow
is irreversible.
- Throws:
-
SQLException
- if there is no current row or an error is encountered resetting the contents of the original row - See Also:
getOriginalRow()
getTableName
String getTableName() throws SQLException
Returns an identifier for the object (table) that was used to create this CachedRowSet
object. This name may be set on multiple occasions, and the specification imposes no limits on how many times this may occur or whether standard implementations should keep track of previous table names.
- Returns:
- a
String
object giving the name of the table that is the source of data for thisCachedRowSet
object ornull
if no name has been set for the table - Throws:
-
SQLException
- if an error is encountered returning the table name - See Also:
ResultSetMetaData.getTableName(int)
setTableName
void setTableName(String tabName) throws SQLException
Sets the identifier for the table from which this CachedRowSet
object was derived to the given table name. The writer uses this name to determine which table to use when comparing the values in the data source with the CachedRowSet
object's values during a synchronization attempt. The table identifier also indicates where modified values from this CachedRowSet
object should be written.
The implementation of this CachedRowSet
object may obtain the the name internally from the RowSetMetaDataImpl
object.
- Parameters:
-
tabName
- aString
object identifying the table from which thisCachedRowSet
object was derived; cannot benull
but may be an empty string - Throws:
-
SQLException
- if an error is encountered naming the table or tabName isnull
- See Also:
-
RowSetMetaData.setTableName(int, java.lang.String)
,RowSetWriter
,SyncProvider
getKeyColumns
int[] getKeyColumns() throws SQLException
Returns an array containing one or more column numbers indicating the columns that form a key that uniquely identifies a row in this CachedRowSet
object.
- Returns:
- an array containing the column number or numbers that indicate which columns constitute a primary key for a row in this
CachedRowSet
object. This array should be empty if no columns are representative of a primary key. - Throws:
-
SQLException
- if thisCachedRowSet
object is empty - See Also:
-
setKeyColumns(int[])
,Joinable.getMatchColumnIndexes()
,Joinable.getMatchColumnNames()
setKeyColumns
void setKeyColumns(int[] keys) throws SQLException
Sets this CachedRowSet
object's keyCols
field with the given array of column numbers, which forms a key for uniquely identifying a row in this CachedRowSet
object.
If a CachedRowSet
object becomes part of a JoinRowSet
object, the keys defined by this method and the resulting constraints are maintained if the columns designated as key columns also become match columns.
- Parameters:
-
keys
- an array ofint
indicating the columns that form a primary key for thisCachedRowSet
object; every element in the array must be greater than0
and less than or equal to the number of columns in this rowset - Throws:
-
SQLException
- if any of the numbers in the given array are not valid for this rowset - See Also:
-
getKeyColumns()
,Joinable.setMatchColumn(String)
,Joinable.setMatchColumn(int)
createShared
RowSet createShared() throws SQLException
Returns a new RowSet
object backed by the same data as that of this CachedRowSet
object. In effect, both CachedRowSet
objects have a cursor over the same data. As a result, any changes made by a duplicate are visible to the original and to any other duplicates, just as a change made by the original is visible to all of its duplicates. If a duplicate calls a method that changes the underlying data, the method it calls notifies all registered listeners just as it would when it is called by the original CachedRowSet
object.
In addition, any RowSet
object created by this method will have the same properties as this CachedRowSet
object. For example, if this CachedRowSet
object is read-only, all of its duplicates will also be read-only. If it is changed to be updatable, the duplicates also become updatable.
NOTE: If multiple threads access RowSet
objects created from the createShared()
method, the following behavior is specified to preserve shared data integrity: reads and writes of all shared RowSet
objects should be made serially between each object and the single underlying tabular structure.
- Returns:
- a new shared
RowSet
object that has the same properties as thisCachedRowSet
object and that has a cursor over the same data - Throws:
-
SQLException
- if an error occurs or cloning is not supported in the underlying platform - See Also:
-
RowSetEvent
,RowSetListener
createCopy
CachedRowSet createCopy() throws SQLException
Creates a RowSet
object that is a deep copy of the data in this CachedRowSet
object. In contrast to the RowSet
object generated from a createShared
call, updates made to the copy of the original RowSet
object must not be visible to the original RowSet
object. Also, any event listeners that are registered with the original RowSet
must not have scope over the new RowSet
copies. In addition, any constraint restrictions established must be maintained.
- Returns:
- a new
RowSet
object that is a deep copy of thisCachedRowSet
object and is completely independent of thisCachedRowSet
object - Throws:
-
SQLException
- if an error occurs in generating the copy of the of thisCachedRowSet
object - See Also:
-
createShared()
,createCopySchema()
,createCopyNoConstraints()
,RowSetEvent
,RowSetListener
createCopySchema
CachedRowSet createCopySchema() throws SQLException
Creates a CachedRowSet
object that is an empty copy of this CachedRowSet
object. The copy must not contain any contents but only represent the table structure of the original CachedRowSet
object. In addition, primary or foreign key constraints set in the originating CachedRowSet
object must be equally enforced in the new empty CachedRowSet
object. In contrast to the RowSet
object generated from a createShared
method call, updates made to a copy of this CachedRowSet
object with the createCopySchema
method must not be visible to it.
Applications can form a WebRowSet
object from the CachedRowSet
object returned by this method in order to export the RowSet
schema definition to XML for future use.
- Returns:
- An empty copy of this
CachedRowSet
object - Throws:
-
SQLException
- if an error occurs in cloning the structure of thisCachedRowSet
object - See Also:
-
createShared()
,createCopySchema()
,createCopyNoConstraints()
,RowSetEvent
,RowSetListener
createCopyNoConstraints
CachedRowSet createCopyNoConstraints() throws SQLException
Creates a CachedRowSet
object that is a deep copy of this CachedRowSet
object's data but is independent of it. In contrast to the RowSet
object generated from a createShared
method call, updates made to a copy of this CachedRowSet
object must not be visible to it. Also, any event listeners that are registered with this CachedRowSet
object must not have scope over the new RowSet
object. In addition, any constraint restrictions established for this CachedRowSet
object must not be maintained in the copy.
- Returns:
- a new
CachedRowSet
object that is a deep copy of thisCachedRowSet
object and is completely independent of thisCachedRowSet
object - Throws:
-
SQLException
- if an error occurs in generating the copy of the of thisCachedRowSet
object - See Also:
-
createCopy()
,createShared()
,createCopySchema()
,RowSetEvent
,RowSetListener
getRowSetWarnings
RowSetWarning getRowSetWarnings() throws SQLException
Retrieves the first warning reported by calls on this RowSet
object. Subsequent warnings on this RowSet
object will be chained to the RowSetWarning
object that this method returns. The warning chain is automatically cleared each time a new row is read. This method may not be called on a RowSet object that has been closed; doing so will cause a SQLException
to be thrown.
- Returns:
- RowSetWarning the first
RowSetWarning
object reported or null if there are none - Throws:
-
SQLException
- if this method is called on a closed RowSet - See Also:
RowSetWarning
getShowDeleted
boolean getShowDeleted() throws SQLException
Retrieves a boolean
indicating whether rows marked for deletion appear in the set of current rows. If true
is returned, deleted rows are visible with the current rows. If false
is returned, rows are not visible with the set of current rows. The default value is false
.
Standard rowset implementations may choose to restrict this behavior due to security considerations or to better fit certain deployment scenarios. This is left as implementation defined and does not represent standard behavior.
Note: Allowing deleted rows to remain visible complicates the behavior of some standard JDBC RowSet
Implementations methods. However, most rowset users can simply ignore this extra detail because only very specialized applications will likely want to take advantage of this feature.
- Returns:
-
true
if deleted rows are visible;false
otherwise - Throws:
-
SQLException
- if a rowset implementation is unable to to determine whether rows marked for deletion are visible - See Also:
setShowDeleted(boolean)
setShowDeleted
void setShowDeleted(boolean b) throws SQLException
Sets the property showDeleted
to the given boolean
value, which determines whether rows marked for deletion appear in the set of current rows. If the value is set to true
, deleted rows are immediately visible with the set of current rows. If the value is set to false
, the deleted rows are set as invisible with the current set of rows.
Standard rowset implementations may choose to restrict this behavior due to security considerations or to better fit certain deployment scenarios. This is left as implementations defined and does not represent standard behavior.
- Parameters:
-
b
-true
if deleted rows should be shown;false
otherwise - Throws:
-
SQLException
- if a rowset implementation is unable to to reset whether deleted rows should be visible - See Also:
getShowDeleted()
commit
void commit() throws SQLException
Each CachedRowSet
object's SyncProvider
contains a Connection
object from the ResultSet
or JDBC properties passed to it's constructors. This method wraps the Connection
commit method to allow flexible auto commit or non auto commit transactional control support.
Makes all changes that are performed by the acceptChanges()
method since the previous commit/rollback permanent. This method should be used only when auto-commit mode has been disabled.
- Throws:
-
SQLException
- if a database access error occurs or this Connection object within thisCachedRowSet
is in auto-commit mode - See Also:
Connection.setAutoCommit(boolean)
rollback
void rollback() throws SQLException
Each CachedRowSet
object's SyncProvider
contains a Connection
object from the original ResultSet
or JDBC properties passed to it.
Undoes all changes made in the current transaction. This method should be used only when auto-commit mode has been disabled.
- Throws:
-
SQLException
- if a database access error occurs or this Connection object within thisCachedRowSet
is in auto-commit mode.
rollback
void rollback(Savepoint s) throws SQLException
Each CachedRowSet
object's SyncProvider
contains a Connection
object from the original ResultSet
or JDBC properties passed to it.
Undoes all changes made in the current transaction back to the last Savepoint
transaction marker. This method should be used only when auto-commit mode has been disabled.
- Parameters:
-
s
- ASavepoint
transaction marker - Throws:
-
SQLException
- if a database access error occurs or this Connection object within thisCachedRowSet
is in auto-commit mode.
rowSetPopulated
void rowSetPopulated(RowSetEvent event, int numRows) throws SQLException
Notifies registered listeners that a RowSet object in the given RowSetEvent object has populated a number of additional rows. The numRows
parameter ensures that this event will only be fired every numRow
.
The source of the event can be retrieved with the method event.getSource.
- Parameters:
-
event
- aRowSetEvent
object that contains theRowSet
object that is the source of the events -
numRows
- when populating, the number of rows interval on which theCachedRowSet
populated should fire; the default value is zero; cannot be less thanfetchSize
or zero - Throws:
-
SQLException
-numRows < 0 or numRows < getFetchSize()
populate
void populate(ResultSet rs, int startRow) throws SQLException
Populates this CachedRowSet
object with data from the given ResultSet
object. While related to the populate(ResultSet)
method, an additional parameter is provided to allow starting position within the ResultSet
from where to populate the CachedRowSet instance.
This method can be used as an alternative to the execute
method when an application has a connection to an open ResultSet
object. Using the method populate
can be more efficient than using the version of the execute
method that takes no parameters because it does not open a new connection and re-execute this CachedRowSet
object's command. Using the populate
method is more a matter of convenience when compared to using the version of execute
that takes a ResultSet
object.
- Parameters:
-
startRow
- the position in theResultSet
from where to start populating the records in thisCachedRowSet
-
rs
- theResultSet
object containing the data to be read into thisCachedRowSet
object - Throws:
-
SQLException
- if a nullResultSet
object is supplied or thisCachedRowSet
object cannot retrieve the associatedResultSetMetaData
object - See Also:
-
execute(java.sql.Connection)
,populate(ResultSet)
,ResultSet
,ResultSetMetaData
setPageSize
void setPageSize(int size) throws SQLException
Sets the CachedRowSet
object's page-size. A CachedRowSet
may be configured to populate itself in page-size sized batches of rows. When either populate()
or execute()
are called, the CachedRowSet
fetches an additional page according to the original SQL query used to populate the RowSet.
- Parameters:
-
size
- the page-size of theCachedRowSet
- Throws:
-
SQLException
- if an error occurs setting theCachedRowSet
page size or if the page size is less than 0.
getPageSize
int getPageSize()
Returns the page-size for the CachedRowSet
object
- Returns:
- an
int
page size
nextPage
boolean nextPage() throws SQLException
Increments the current page of the CachedRowSet
. This causes the CachedRowSet
implementation to fetch the next page-size rows and populate the RowSet, if remaining rows remain within scope of the original SQL query used to populated the RowSet.
- Returns:
- true if more pages exist; false if this is the last page
- Throws:
-
SQLException
- if an error occurs fetching the next page, or if this method is called prematurely before populate or execute.
previousPage
boolean previousPage() throws SQLException
Decrements the current page of the CachedRowSet
. This causes the CachedRowSet
implementation to fetch the previous page-size rows and populate the RowSet. The amount of rows returned in the previous page must always remain within scope of the original SQL query used to populate the RowSet.
- Returns:
- true if the previous page is successfully retrieved; false if this is the first page.
- Throws:
-
SQLException
- if an error occurs fetching the previous page, or if this method is called prematurely before populate or execute.