Interface SQLData
public interface SQLData
The interface used for the custom mapping of an SQL user-defined type (UDT) to a class in the Java programming language. The class object for a class implementing the SQLData
interface will be entered in the appropriate Connection
object's type map along with the SQL name of the UDT for which it is a custom mapping.
Typically, a SQLData
implementation will define a field for each attribute of an SQL structured type or a single field for an SQL DISTINCT
type. When the UDT is retrieved from a data source with the ResultSet.getObject
method, it will be mapped as an instance of this class. A programmer can operate on this class instance just as on any other object in the Java programming language and then store any changes made to it by calling the PreparedStatement.setObject
method, which will map it back to the SQL type.
It is expected that the implementation of the class for a custom mapping will be done by a tool. In a typical implementation, the programmer would simply supply the name of the SQL UDT, the name of the class to which it is being mapped, and the names of the fields to which each of the attributes of the UDT is to be mapped. The tool will use this information to implement the SQLData.readSQL
and SQLData.writeSQL
methods. The readSQL
method calls the appropriate SQLInput
methods to read each attribute from an SQLInput
object, and the writeSQL
method calls SQLOutput
methods to write each attribute back to the data source via an SQLOutput
object.
An application programmer will not normally call SQLData
methods directly, and the SQLInput
and SQLOutput
methods are called internally by SQLData
methods, not by application code.
- Since:
- 1.2
Method Summary
Modifier and Type | Method | Description |
---|---|---|
String | getSQLTypeName() | Returns the fully-qualified name of the SQL user-defined type that this object represents. |
void | readSQL(SQLInput stream,
String typeName) | Populates this object with data read from the database. |
void | writeSQL(SQLOutput stream) | Writes this object to the given SQL data stream, converting it back to its SQL value in the data source. |
Method Detail
getSQLTypeName
String getSQLTypeName() throws SQLException
Returns the fully-qualified name of the SQL user-defined type that this object represents. This method is called by the JDBC driver to get the name of the UDT instance that is being mapped to this instance of SQLData
.
- Returns:
- the type name that was passed to the method
readSQL
when this object was constructed and populated - Throws:
-
SQLException
- if there is a database access error -
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method - Since:
- 1.2
readSQL
void readSQL(SQLInput stream, String typeName) throws SQLException
Populates this object with data read from the database. The implementation of the method must follow this protocol:
- It must read each of the attributes or elements of the SQL type from the given input stream. This is done by calling a method of the input stream to read each item, in the order that they appear in the SQL definition of the type.
- The method
readSQL
then assigns the data to appropriate fields or elements (of this or other objects). Specifically, it must call the appropriate reader method (SQLInput.readString
,SQLInput.readBigDecimal
, and so on) method(s) to do the following: for a distinct type, read its single data element; for a structured type, read a value for each attribute of the SQL type.
SQLInput
reader method on the stream. - Parameters:
-
stream
- theSQLInput
object from which to read the data for the value that is being custom mapped -
typeName
- the SQL type name of the value on the data stream - Throws:
-
SQLException
- if there is a database access error -
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method - Since:
- 1.2
- See Also:
SQLInput
writeSQL
void writeSQL(SQLOutput stream) throws SQLException
Writes this object to the given SQL data stream, converting it back to its SQL value in the data source. The implementation of the method must follow this protocol:
It must write each of the attributes of the SQL type to the given output stream. This is done by calling a method of the output stream to write each item, in the order that they appear in the SQL definition of the type. Specifically, it must call the appropriate SQLOutput
writer method(s) (writeInt
, writeString
, and so on) to do the following: for a Distinct Type, write its single data element; for a Structured Type, write a value for each attribute of the SQL type.
- Parameters:
-
stream
- theSQLOutput
object to which to write the data for the value that was custom mapped - Throws:
-
SQLException
- if there is a database access error -
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method - Since:
- 1.2
- See Also:
SQLOutput