Module java.sql.rowset

Package javax.sql.rowset.serial

Class SerialBlob

java.lang.Object

javax.sql.rowset.serial.SerialBlob

All Implemented Interfaces:

Serializable, Cloneable, Blob

public class SerialBlob
extends Object
implements Blob, Serializable, Cloneable

A serialized mapping in the Java programming language of an SQL BLOB value.

The SerialBlob class provides a constructor for creating an instance from a Blob object. Note that the Blob object should have brought the SQL BLOB value's data over to the client before a SerialBlob object is constructed from it. The data of an SQL BLOB value can be materialized on the client as an array of bytes (using the method Blob.getBytes) or as a stream of uninterpreted bytes (using the method Blob.getBinaryStream).

SerialBlob methods make it possible to make a copy of a SerialBlob object as an array of bytes or as a stream. They also make it possible to locate a given pattern of bytes or a Blob object within a SerialBlob object and to update or truncate a Blob object.

Thread safety

A SerialBlob is not safe for use by multiple concurrent threads. If a SerialBlob is to be used by more than one thread then access to the SerialBlob should be controlled by appropriate synchronization.

Since:

1.5

See Also:

• Serialized Form

Constructor Summary

Constructors

Constructor	Description
SerialBlob(byte[] b)	Constructs a SerialBlob object that is a serialized version of the given byte array.
SerialBlob(Blob blob)	Constructs a SerialBlob object that is a serialized version of the given Blob object.

Method Summary

Modifier and Type	Method	Description
Object	clone()	Returns a clone of this SerialBlob.
boolean	equals(Object obj)	Compares this SerialBlob to the specified object.
void	free()	This method frees the SerialBlob object and releases the resources that it holds.
InputStream	getBinaryStream()	Returns this SerialBlob object as an input 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)	Copies the specified number of bytes, starting at the given position, from this SerialBlob object to another array of bytes.
int	hashCode()	Returns a hash code for this SerialBlob.
long	length()	Retrieves the number of bytes in this SerialBlob object's array of bytes.
long	position(byte[] pattern, long start)	Returns the position in this SerialBlob object where the given pattern of bytes begins, starting the search at the specified position.
long	position(Blob pattern, long start)	Returns the position in this SerialBlob object where the given Blob object begins, starting the search at the specified position.
OutputStream	setBinaryStream(long pos)	Retrieves a stream that can be used to write to the BLOB value that this Blob object represents.
int	setBytes(long pos, byte[] bytes)	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.
int	setBytes(long pos, byte[] bytes, int offset, int length)	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.
void	truncate(long length)	Truncates the BLOB value that this Blob object represents to be len bytes in length.

Methods declared in class java.lang.Object

finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Details

SerialBlob

public SerialBlob(byte[] b)
           throws SerialException,
SQLException

Constructs a SerialBlob object that is a serialized version of the given byte array.

The new SerialBlob object is initialized with the data from the byte array, thus allowing disconnected RowSet objects to establish serialized Blob objects without touching the data source.

Parameters:

b - the byte array containing the data for the Blob object to be serialized

Throws:

SerialException - if an error occurs during serialization

SQLException - if a SQL errors occurs

SerialBlob

public SerialBlob(Blob blob)
           throws SerialException,
SQLException

Constructs a SerialBlob object that is a serialized version of the given Blob object.

The new SerialBlob object is initialized with the data from the Blob object; therefore, the Blob object should have previously brought the SQL BLOB value's data over to the client from the database. Otherwise, the new SerialBlob object will contain no data.

Parameters:

blob - the Blob object from which this SerialBlob object is to be constructed; cannot be null.

Throws:

SerialException - if an error occurs during serialization

SQLException - if the Blob passed to this to this constructor is a null.

See Also:

• Blob

Method Details

getBytes

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

Copies the specified number of bytes, starting at the given position, from this SerialBlob object to another array of bytes.

Note that if the given number of bytes to be copied is larger than the length of this SerialBlob object's array of bytes, the given number will be shortened to the array's length.

Specified by:

getBytes in interface Blob

Parameters:

pos - the ordinal position of the first byte in this SerialBlob object to be copied; numbering starts at 1; must not be less than 1 and must be less than or equal to the length of this SerialBlob object

length - the number of bytes to be copied

Returns:

an array of bytes that is a copy of a region of this SerialBlob object, starting at the given position and containing the given number of consecutive bytes

Throws:

SerialException - if the given starting position is out of bounds; if free had previously been called on this object

See Also:

• Blob.setBytes(long, byte[])

length

public long length()
            throws SerialException

Retrieves the number of bytes in this SerialBlob object's array of bytes.

Specified by:

length in interface Blob

Returns:

a long indicating the length in bytes of this SerialBlob object's array of bytes

Throws:

SerialException - if an error occurs; if free had previously been called on this object

getBinaryStream

public InputStream getBinaryStream()
                            throws SerialException

Returns this SerialBlob object as an input stream. Unlike the related method, setBinaryStream, a stream is produced regardless of whether the SerialBlob was created with a Blob object or a byte array.

Specified by:

getBinaryStream in interface Blob

Returns:

a java.io.InputStream object that contains this SerialBlob object's array of bytes

Throws:

SerialException - if an error occurs; if free had previously been called on this object

See Also:

• setBinaryStream(long)

position

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

Returns the position in this SerialBlob object where the given pattern of bytes begins, starting the search at the specified position.

Specified by:

position in interface Blob

Parameters:

pattern - the pattern of bytes for which to search

start - the position of the byte in this SerialBlob object from which to begin the search; the first position is 1; must not be less than 1 nor greater than the length of this SerialBlob object

Returns:

the position in this SerialBlob object where the given pattern begins, starting at the specified position; -1 if the pattern is not found or the given starting position is out of bounds; position numbering for the return value starts at 1

Throws:

SerialException - if an error occurs when serializing the blob; if free had previously been called on this object

SQLException - if there is an error accessing the BLOB value from the database

position

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

Returns the position in this SerialBlob object where the given Blob object begins, starting the search at the specified position.

Specified by:

position in interface Blob

Parameters:

pattern - the Blob object for which to search;

start - the position of the byte in this SerialBlob object from which to begin the search; the first position is 1; must not be less than 1 nor greater than the length of this SerialBlob object

Returns:

the position in this SerialBlob object where the given Blob object begins, starting at the specified position; -1 if the pattern is not found or the given starting position is out of bounds; position numbering for the return value starts at 1

Throws:

SerialException - if an error occurs when serializing the blob; if free had previously been called on this object

SQLException - if there is an error accessing the BLOB value from the database

setBytes

public int setBytes(long pos,
 byte[] bytes)
             throws SerialException,
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.

Specified by:

setBytes in interface Blob

Parameters:

pos - the position in the SQL BLOB value at which to start writing. The first position is 1; must not be less than 1 nor greater than the length+1 of this SerialBlob object.

bytes - the array of bytes to be written to the BLOB value that this Blob object represents

Returns:

the number of bytes written

Throws:

SerialException - if there is an error accessing the BLOB value; or if an invalid position is set; if free had previously been called on this object

SQLException - if there is an error accessing the BLOB value from the database

See Also:

• getBytes(long, int)

setBytes

public int setBytes(long pos,
 byte[] bytes,
 int offset,
 int length)
             throws SerialException,
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; length bytes from the given byte array are written.

Specified by:

setBytes in interface Blob

Parameters:

pos - the position in the BLOB object at which to start writing. The first position is 1; must not be less than 1 nor greater than the length+1 of this SerialBlob object.

bytes - the array of bytes to be written to the BLOB value

offset - the offset into the array bytes at which to start reading the bytes to be set. The first offset position is 0; must not be less than 0 nor greater than the length of the array bytes

length - the number of bytes to be written to the BLOB value from the array of bytes bytes

Returns:

the number of bytes written

Throws:

SerialException - if there is an error accessing the BLOB value; if an invalid position is set; if an invalid offset value is set; or the combined values of the length and offset is greater than the length of bytes; if free had previously been called on this object

SQLException - if there is an error accessing the BLOB value from the database.

See Also:

• getBytes(long, int)

setBinaryStream

public OutputStream setBinaryStream(long pos)
                             throws SerialException,
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. This method forwards the setBinaryStream() call to the underlying Blob in the event that this SerialBlob object is instantiated with a Blob. If this SerialBlob is instantiated with a byte array, a SerialException is thrown.

Specified by:

setBinaryStream in interface Blob

Parameters:

pos - the position in the BLOB value at which to start writing

Returns:

a java.io.OutputStream object to which data can be written

Throws:

SQLException - if there is an error accessing the BLOB value

SerialException - if the SerialBlob in not instantiated with a Blob object that supports setBinaryStream(); if free had previously been called on this object

See Also:

• getBinaryStream()

truncate

public void truncate(long length)
              throws SerialException

Truncates the BLOB value that this Blob object represents to be len bytes in length.

Specified by:

truncate in interface Blob

Parameters:

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

Throws:

SerialException - if there is an error accessing the Blob value; or the length to truncate is greater that the SerialBlob length; if free had previously been called on this object

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.

Throws:

SQLException - if pos is less than 1 or if pos is greater than the number of bytes in the Blob or if pos + length is greater than the number of bytes in the Blob

SerialException - if the free method had been previously called on this object

Since:

1.6

free

public void free()
          throws SQLException

This method frees the SerialBlob object and releases the resources that it holds. The object is invalid once the free method is called.

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

Specified by:

free in interface Blob

Throws:

SQLException - if an error occurs releasing the Blob's resources

Since:

1.6

equals

public boolean equals(Object obj)

Compares this SerialBlob to the specified object. The result is true if and only if the argument is not null and is a SerialBlob object that represents the same sequence of bytes as this object.

Overrides:

equals in class Object

Parameters:

obj - The object to compare this SerialBlob against

Returns:

true if the given object represents a SerialBlob equivalent to this SerialBlob, false otherwise

See Also:

• Object.hashCode()
• HashMap

hashCode

public int hashCode()

Returns a hash code for this SerialBlob.

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

See Also:

• Object.equals(java.lang.Object)
• System.identityHashCode(java.lang.Object)

clone

public Object clone()

Returns a clone of this SerialBlob. The copy will contain a reference to a clone of the internal byte array, not a reference to the original internal byte array of this SerialBlob object. The underlying Blob object will be set to null.

Overrides:

clone in class Object

Returns:

a clone of this SerialBlob

See Also:

• Cloneable