Interface Blob
- All Known Implementing Classes:
SerialBlob
public interface Blob
The representation (mapping) in the Java™ programming language of an SQL BLOB
value. An SQL BLOB
is a built-in type that stores a Binary Large Object as a column value in a row of a database table. By default drivers implement Blob
using an SQL locator(BLOB)
, which means that a Blob
object contains a logical pointer to the SQL BLOB
data rather than the data itself. A Blob
object is valid for the duration of the transaction in which is was created.
Methods in the interfaces ResultSet
, CallableStatement
, and PreparedStatement
, such as getBlob
and setBlob
allow a programmer to access an SQL BLOB
value. The Blob
interface provides methods for getting the length of an SQL BLOB
(Binary Large Object) value, for materializing a BLOB
value on the client, and for determining the position of a pattern of bytes within a BLOB
value. In addition, this interface has methods for updating a BLOB
value.
All methods on the Blob
interface must be fully implemented if the JDBC driver supports the data type.
- Since:
- 1.2
Method Summary
Modifier and Type | Method | Description |
---|---|---|
void | free() | This method frees the |
InputStream | getBinaryStream() | Retrieves the |
InputStream | getBinaryStream(long pos,
long length) | Returns an |
byte[] | getBytes(long pos,
int length) | Retrieves all or part of the |
long | length() | Returns the number of bytes in the |
long | position(byte[] pattern,
long start) | Retrieves the byte position at which the specified byte array |
long | position(Blob pattern,
long start) | Retrieves the byte position in the |
OutputStream | setBinaryStream(long pos) | Retrieves a stream that can be used to write to the |
int | setBytes(long pos,
byte[] bytes) | Writes the given array of bytes to the |
int | setBytes(long pos,
byte[] bytes,
int offset,
int len) | Writes all or part of the given |
void | truncate(long len) | Truncates the |
Method Detail
length
long length() throws SQLException
Returns the number of bytes in the BLOB
value designated by this Blob
object.
- Returns:
- length of the
BLOB
in bytes - Throws:
-
SQLException
- if there is an error accessing the length of theBLOB
-
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method - Since:
- 1.2
getBytes
byte[] getBytes(long pos, int length) throws SQLException
Retrieves all or part of the BLOB
value that this Blob
object represents, as an array of bytes. This byte
array contains up to length
consecutive bytes starting at position pos
.
- Parameters:
-
pos
- the ordinal position of the first byte in theBLOB
value to be extracted; the first byte is at position 1 -
length
- the number of consecutive bytes to be copied; the value for length must be 0 or greater - Returns:
- a byte array containing up to
length
consecutive bytes from theBLOB
value designated by thisBlob
object, starting with the byte at positionpos
- Throws:
-
SQLException
- if there is an error accessing theBLOB
value; if pos is less than 1 or length is less than 0 -
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method - Since:
- 1.2
- See Also:
setBytes(long, byte[])
getBinaryStream
InputStream getBinaryStream() throws SQLException
Retrieves the BLOB
value designated by this Blob
instance as a stream.
- Returns:
- a stream containing the
BLOB
data - Throws:
-
SQLException
- if there is an error accessing theBLOB
value -
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method - Since:
- 1.2
- See Also:
setBinaryStream(long)
position
long position(byte[] pattern, long start) throws SQLException
Retrieves the byte position at which the specified byte array pattern
begins within the BLOB
value that this Blob
object represents. The search for pattern
begins at position start
.
- Parameters:
-
pattern
- the byte array for which to search -
start
- the position at which to begin searching; the first position is 1 - Returns:
- the position at which the pattern appears, else -1
- Throws:
-
SQLException
- if there is an error accessing theBLOB
or if start is less than 1 -
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method - Since:
- 1.2
position
long position(Blob pattern, long start) throws SQLException
Retrieves the byte position in the BLOB
value designated by this Blob
object at which pattern
begins. The search begins at position start
.
- Parameters:
-
pattern
- theBlob
object designating theBLOB
value for which to search -
start
- the position in theBLOB
value at which to begin searching; the first position is 1 - Returns:
- the position at which the pattern begins, else -1
- Throws:
-
SQLException
- if there is an error accessing theBLOB
value or if start is less than 1 -
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method - Since:
- 1.2
setBytes
int setBytes(long pos, byte[] bytes) throws SQLException
Writes the given array of bytes to the BLOB
value that this Blob
object represents, starting at position pos
, and returns the number of bytes written. The array of bytes will overwrite the existing bytes in the Blob
object starting at the position pos
. If the end of the Blob
value is reached while writing the array of bytes, then the length of the Blob
value will be increased to accommodate the extra bytes.
Note: If the value specified for pos
is greater than the length+1 of the BLOB
value then the behavior is undefined. Some JDBC drivers may throw an SQLException
while other drivers may support this operation.
- Parameters:
-
pos
- the position in theBLOB
object at which to start writing; the first position is 1 -
bytes
- the array of bytes to be written to theBLOB
value that thisBlob
object represents - Returns:
- the number of bytes written
- Throws:
-
SQLException
- if there is an error accessing theBLOB
value or if pos is less than 1 -
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method - Since:
- 1.4
- See Also:
getBytes(long, int)
setBytes
int setBytes(long pos, byte[] bytes, int offset, int len) throws SQLException
Writes all or part of the given byte
array to the BLOB
value that this Blob
object represents and returns the number of bytes written. Writing starts at position pos
in the BLOB
value; len
bytes from the given byte array are written. The array of bytes will overwrite the existing bytes in the Blob
object starting at the position pos
. If the end of the Blob
value is reached while writing the array of bytes, then the length of the Blob
value will be increased to accommodate the extra bytes.
Note: If the value specified for pos
is greater than the length+1 of the BLOB
value then the behavior is undefined. Some JDBC drivers may throw an SQLException
while other drivers may support this operation.
- Parameters:
-
pos
- the position in theBLOB
object at which to start writing; the first position is 1 -
bytes
- the array of bytes to be written to thisBLOB
object -
offset
- the offset into the arraybytes
at which to start reading the bytes to be set -
len
- the number of bytes to be written to theBLOB
value from the array of bytesbytes
- Returns:
- the number of bytes written
- Throws:
-
SQLException
- if there is an error accessing theBLOB
value or if pos is less than 1 -
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method - Since:
- 1.4
- See Also:
getBytes(long, int)
setBinaryStream
OutputStream setBinaryStream(long pos) throws SQLException
Retrieves a stream that can be used to write to the BLOB
value that this Blob
object represents. The stream begins at position pos
. The bytes written to the stream will overwrite the existing bytes in the Blob
object starting at the position pos
. If the end of the Blob
value is reached while writing to the stream, then the length of the Blob
value will be increased to accommodate the extra bytes.
Note: If the value specified for pos
is greater than the length+1 of the BLOB
value then the behavior is undefined. Some JDBC drivers may throw an SQLException
while other drivers may support this operation.
- Parameters:
-
pos
- the position in theBLOB
value at which to start writing; the first position is 1 - Returns:
- a
java.io.OutputStream
object to which data can be written - Throws:
-
SQLException
- if there is an error accessing theBLOB
value or if pos is less than 1 -
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method - Since:
- 1.4
- See Also:
getBinaryStream()
truncate
void truncate(long len) throws SQLException
Truncates the BLOB
value that this Blob
object represents to be len
bytes in length.
Note: If the value specified for pos
is greater than the length+1 of the BLOB
value then the behavior is undefined. Some JDBC drivers may throw an SQLException
while other drivers may support this operation.
- Parameters:
-
len
- the length, in bytes, to which theBLOB
value that thisBlob
object represents should be truncated - Throws:
-
SQLException
- if there is an error accessing theBLOB
value or if len is less than 0 -
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method - Since:
- 1.4
free
void free() throws SQLException
This method frees the Blob
object and releases the resources that it holds. The object is invalid once the free
method is called.
After free
has been called, any attempt to invoke a method other than free
will result in an SQLException
being thrown. If free
is called multiple times, the subsequent calls to free
are treated as a no-op.
- Throws:
-
SQLException
- if an error occurs releasing the Blob's resources -
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method - Since:
- 1.6
getBinaryStream
InputStream getBinaryStream(long pos, long length) throws SQLException
Returns an InputStream
object that contains a partial Blob
value, starting with the byte specified by pos, which is length bytes in length.
- Parameters:
-
pos
- the offset to the first byte of the partial value to be retrieved. The first byte in theBlob
is at position 1. -
length
- the length in bytes of the partial value to be retrieved - Returns:
-
InputStream
through which the partialBlob
value can be read. - Throws:
-
SQLException
- if pos is less than 1 or if pos is greater than the number of bytes in theBlob
or if pos + length is greater than the number of bytes in theBlob
-
SQLFeatureNotSupportedException
- if the JDBC driver does not support this method - Since:
- 1.6