Class Blob

java.lang.Object

com.mysql.jdbc.Blob

All Implemented Interfaces:

OutputStreamWatcher, Blob

public class Blob
extends Object
implements Blob, OutputStreamWatcher

The representation (mapping) in the JavaTM 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. The driver implements 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. This class is new in the JDBC 2.0 API.

Constructor Summary

Constructors

Constructor	Description
Blob(byte[] data, ExceptionInterceptor exceptionInterceptor)	Creates a BLOB encapsulating the given binary data
Blob(byte[] data, ResultSetInternalMethods creatorResultSetToSet, int columnIndexToSet)	Creates an updatable BLOB that can update in-place (not implemented yet).
Blob(ExceptionInterceptor exceptionInterceptor)	Creates a Blob without data

Method Summary

Modifier and Type	Method	Description
void	free()	This method frees the Blob object and releases the resources that it holds.
InputStream	getBinaryStream()	Retrieves the BLOB designated by this Blob instance as a stream.
InputStream	getBinaryStream(long pos, long length)	Returns an InputStream object that contains a partial Blob value, starting with the byte specified by pos, which is length bytes in length.
byte[]	getBytes(long pos, int length)	Returns as an array of bytes, part or all of the BLOB value that this Blob object designates.
long	length()	Returns the number of bytes in the BLOB value designated by this Blob object.
long	position(byte[] pattern, long start)
long	position(Blob pattern, long start)	Finds the position of the given pattern in this BLOB.
OutputStream	setBinaryStream(long indexToWriteAt)
int	setBytes(long writeAt, byte[] bytes)
int	setBytes(long writeAt, byte[] bytes, int offset, int length)
void	streamClosed(byte[] byteData)
void	streamClosed(WatchableOutputStream out)	Called when the OutputStream being watched has .close() called
void	truncate(long len)	Truncates the BLOB value that this Blob object represents to be len bytes in length.

Methods inherited from class Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Blob

Blob(ExceptionInterceptor exceptionInterceptor)

Creates a Blob without data

Blob

Blob(byte[] data,
 ExceptionInterceptor exceptionInterceptor)

Creates a BLOB encapsulating the given binary data

Parameters:

data -

Blob

Blob(byte[] data,
 ResultSetInternalMethods creatorResultSetToSet,
 int columnIndexToSet)

Creates an updatable BLOB that can update in-place (not implemented yet).

Parameters:

data -

creatorResultSetToSet -

columnIndexToSet -

Method Details

getBinaryStream

public InputStream getBinaryStream()
                            throws SQLException

Retrieves the BLOB designated by this Blob instance as a stream.

Specified by:

getBinaryStream in interface Blob

Returns:

this BLOB represented as a binary stream of bytes.

Throws:

SQLException - if a database error occurs

getBytes

public byte[] getBytes(long pos,
 int length)
                throws SQLException

Returns as an array of bytes, part or all of the BLOB value that this Blob object designates.

Specified by:

getBytes in interface Blob

Parameters:

pos - where to start the part of the BLOB

length - the length of the part of the BLOB you want returned.

Returns:

the bytes stored in the blob starting at position pos and having a length of length.

Throws:

SQLException - if a database error occurs

length

public long length()
            throws SQLException

Returns the number of bytes in the BLOB value designated by this Blob object.

Specified by:

length in interface Blob

Returns:

the length of this blob

Throws:

SQLException - if a database error occurs

position

public long position(byte[] pattern,
 long start)
              throws SQLException

Specified by:

position in interface Blob

Throws:

SQLException

See Also:

• Blob.position(byte[], long)

position

public long position(Blob pattern,
 long start)
              throws SQLException

Finds the position of the given pattern in this BLOB.

Specified by:

position in interface Blob

Parameters:

pattern - the pattern to find

start - where to start finding the pattern

Returns:

the position where the pattern is found in the BLOB, -1 if not found

Throws:

SQLException - if a database error occurs

setBinaryStream

public OutputStream setBinaryStream(long indexToWriteAt)
                             throws SQLException

Specified by:

setBinaryStream in interface Blob

Throws:

SQLException

See Also:

• setBinaryStream(long)

setBytes

public int setBytes(long writeAt,
 byte[] bytes)
             throws SQLException

Specified by:

setBytes in interface Blob

Throws:

SQLException

See Also:

• setBytes(long, byte[])

setBytes

public int setBytes(long writeAt,
 byte[] bytes,
 int offset,
 int length)
             throws SQLException

Specified by:

setBytes in interface Blob

Throws:

SQLException

See Also:

• setBytes(long, byte[], int, int)

streamClosed

public void streamClosed(byte[] byteData)

See Also:

• invalid reference

  com.mysql.jdbc.OutputStreamWatcher#streamClosed(byte[])

streamClosed

public void streamClosed(WatchableOutputStream out)

Description copied from interface: OutputStreamWatcher

Called when the OutputStream being watched has .close() called

Specified by:

streamClosed in interface OutputStreamWatcher

See Also:

• invalid reference

  com.mysql.jdbc.OutputStreamWatcher#streamClosed(byte[])

truncate

public 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 len is greater then the length+1 of the BLOB value then the behavior is undefined. Some JDBC drivers may throw a SQLException while other drivers may support this operation.

Specified by:

truncate in interface Blob

Parameters:

len - the length, in bytes, to which the BLOB value that this Blob object represents should be truncated

Since:

1.4

free

public 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 a SQLException being thrown. If free is called multiple times, the subsequent calls to free are treated as a no-op.

Specified by:

free in interface Blob

Since:

1.6

getBinaryStream

public 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.

Specified by:

getBinaryStream in interface Blob

Parameters:

pos - the offset to the first byte of the partial value to be retrieved. The first byte in the Blob is at position 1

length - the length in bytes of the partial value to be retrieved

Returns:

InputStream through which the partial Blob value can be read.

Since:

1.6