org.firebirdsql.jdbc

Class FBBlob

java.lang.Object

org.firebirdsql.jdbc.FBBlob

All Implemented Interfaces:

java.sql.Blob, FirebirdBlob, Synchronizable

public class FBBlob
extends java.lang.Object
implements FirebirdBlob, Synchronizable

The representation (mapping) in the Java^TM 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.

Since:

1.2

Nested Class Summary

Nested classes/interfaces inherited from interface org.firebirdsql.jdbc.FirebirdBlob

FirebirdBlob.BlobInputStream, FirebirdBlob.BlobOutputStream

Field Summary

Fields

Modifier and Type	Field and Description
static byte[]	BLOB_LENGTH_REQUEST
static int	READ_FULLY_BUFFER_SIZE Maximum blob segment size, see IB 6 Data Definition Guide, page 78 ("BLOB segment length")
static boolean	SEGMENTED

Constructor Summary

Constructors

Constructor and Description
FBBlob(org.firebirdsql.gds.impl.GDSHelper c)
FBBlob(org.firebirdsql.gds.impl.GDSHelper c, FBObjectListener.BlobListener blobListener) Create new Blob instance.
FBBlob(org.firebirdsql.gds.impl.GDSHelper c, long blob_id) Create instance of this class to access existing Blob.
FBBlob(org.firebirdsql.gds.impl.GDSHelper c, long blob_id, FBObjectListener.BlobListener blobListener) Create instance of this class to access existing Blob.

Method Summary

Modifier and Type	Method and Description
void	close() Close this Blob object.
void	copyBytes(byte[] bytes, int pos, int len)
void	copyCharacterStream(java.io.Reader inputStream, int length, java.lang.String encoding) Copy data from a character stream into this Blob.
void	copyStream(java.io.InputStream inputStream) Copy the contents of an InputStream into this Blob.
void	copyStream(java.io.InputStream inputStream, int length) Copy the contents of an InputStream into this Blob.
FirebirdBlob	detach() Detach this blob.
void	free() This method frees the Blob object and releases the resources that it holds.
java.io.InputStream	getBinaryStream() Retrieves the BLOB designated by this Blob instance as a stream.
java.io.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.
long	getBlobId() Get the identifier for this Blob
byte[]	getBytes(long pos, int length) Returns as an array of bytes, part or all of the BLOB value that this Blob object designates.
byte[]	getInfo(byte[] items, int buffer_length) Get information about this Blob.
java.lang.Object	getSynchronizationObject() Get synchronization object.
static long	interpretLength(org.firebirdsql.gds.impl.GDSHelper gdsHelper, byte[] info, int position) Interpret BLOB length from buffer.
boolean	isSegmented() Check if blob is segmented.
long	length() Returns the number of bytes in the BLOB value designated by this Blob object.
long	position(java.sql.Blob pattern, long start) Determines the byte position in the BLOB value designated by this Blob object at which pattern begins.
long	position(byte[] pattern, long start) Determines the byte position at which the specified byte pattern begins within the BLOB value that this Blob object represents.
java.io.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 param1, byte[] param2) This operation is not currently supported 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.
int	setBytes(long param1, byte[] param2, int param3, int param4) This operation is not currently supported 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 param1) This operation is not currently supported Truncate this Blob to a given length.

Methods inherited from class java.lang.Object

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

Field Detail

SEGMENTED

public static final boolean SEGMENTED

See Also:

Constant Field Values

READ_FULLY_BUFFER_SIZE

public static final int READ_FULLY_BUFFER_SIZE

Maximum blob segment size, see IB 6 Data Definition Guide, page 78 ("BLOB segment length")

See Also:

Constant Field Values

BLOB_LENGTH_REQUEST

public static final byte[] BLOB_LENGTH_REQUEST

Constructor Detail

FBBlob

public FBBlob(org.firebirdsql.gds.impl.GDSHelper c,
              FBObjectListener.BlobListener blobListener)

Create new Blob instance. This constructor creates new fresh Blob, only writing to the Blob is allowed.

Parameters:

c - connection that will be used to write data to blob.

FBBlob

public FBBlob(org.firebirdsql.gds.impl.GDSHelper c)

FBBlob

public FBBlob(org.firebirdsql.gds.impl.GDSHelper c,
              long blob_id,
              FBObjectListener.BlobListener blobListener)

Create instance of this class to access existing Blob.

Parameters:

c - connection that will be used to access Blob.

blob_id - ID of the Blob.

blobListener - Blob listener instance

FBBlob

public FBBlob(org.firebirdsql.gds.impl.GDSHelper c,
              long blob_id)

Create instance of this class to access existing Blob.

Parameters:

c - connection that will be used to access Blob.

blob_id - ID of the Blob.

Method Detail

getSynchronizationObject

public final java.lang.Object getSynchronizationObject()

Description copied from interface: Synchronizable

Get synchronization object.

Specified by:

getSynchronizationObject in interface Synchronizable

Returns:

object, cannot be null.

close

public void close()
           throws java.io.IOException

Close this Blob object. This method closes all open input streams.

Throws:

java.io.IOException - if at least one of the stream raised an exception when closed.

free

public void free()
          throws java.sql.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 java.sql.Blob

Throws:

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

java.sql.SQLFeatureNotSupportedException - if the JDBC driver does not support this method

Since:

1.6

getBinaryStream

public java.io.InputStream getBinaryStream(long pos,
                                           long length)
                                    throws java.sql.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 java.sql.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:

java.sql.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

java.sql.SQLFeatureNotSupportedException - if the JDBC driver does not support this method

Since:

1.6

getInfo

public byte[] getInfo(byte[] items,
                      int buffer_length)
               throws java.sql.SQLException

Get information about this Blob. This method should be considered as temporary because it provides access to low-level API. More information on how to use the API can be found in "API Guide".

Parameters:

items - items in which we are interested.

buffer_length - buffer where information will be stored.

Returns:

array of bytes containing information about this Blob.

Throws:

java.sql.SQLException - if something went wrong.

length

public long length()
            throws java.sql.SQLException

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

Specified by:

length in interface java.sql.Blob

Returns:

length of the BLOB in bytes

Throws:

java.sql.SQLException - if there is an error accessing the length of the BLOB

Since:

1.2

See Also:

What Is in the JDBC 2.0 API

interpretLength

public static long interpretLength(org.firebirdsql.gds.impl.GDSHelper gdsHelper,
                                   byte[] info,
                                   int position)
                            throws java.sql.SQLException

Interpret BLOB length from buffer.

Parameters:

info - server response.

position - where to start interpreting.

Returns:

length of the blob.

Throws:

java.sql.SQLException - if length cannot be interpreted.

isSegmented

public boolean isSegmented()
                    throws java.sql.SQLException

Check if blob is segmented.

Specified by:

isSegmented in interface FirebirdBlob

Returns:

true if this blob is segmented, otherwise false

Throws:

java.sql.SQLException - if something went wrong.

detach

public FirebirdBlob detach()
                    throws java.sql.SQLException

Detach this blob. This method creates new instance of the same blob database object that is not under result set control. When result set is closed, all associated resources are also released, including open blob streams. This method creates an new instance of blob object with the same blob ID that can be used even when result set is closed.

Note, detached blob will not remember the stream position of this object. This means that you cannot start reading data from the blob, then detach it, and then continue reading. Reading from detached blob will begin at the blob start.

Specified by:

detach in interface FirebirdBlob

Returns:

instance of FBBlob that is not under result set control.

Throws:

java.sql.SQLException - if Blob cannot be detached.

getBytes

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

Returns as an array of bytes, part or all of the BLOB value that this Blob object designates. The byte array contains up to length consecutive bytes starting at position pos.

Specified by:

getBytes in interface java.sql.Blob

Parameters:

pos - the ordinal position of the first byte in the BLOB value to be extracted; the first byte is at position 1

length - the number of consecutive bytes to be copied

Returns:

a byte array containing up to length consecutive bytes from the BLOB value designated by this Blob object, starting with the byte at position pos

Throws:

java.sql.SQLException - if there is an error accessing the BLOB

Since:

1.2

See Also:

What Is in the JDBC 2.0 API

getBinaryStream

public java.io.InputStream getBinaryStream()
                                    throws java.sql.SQLException

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

Specified by:

getBinaryStream in interface java.sql.Blob

Returns:

a stream containing the BLOB data

Throws:

java.sql.SQLException - if there is an error accessing the BLOB

Since:

1.2

See Also:

What Is in the JDBC 2.0 API

position

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

Determines the byte position at which the specified byte pattern begins within the BLOB value that this Blob object represents. The search for pattern begins at position start.

Specified by:

position in interface java.sql.Blob

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:

java.sql.SQLException - if there is an error accessing the BLOB

Since:

1.2

See Also:

What Is in the JDBC 2.0 API

position

public long position(java.sql.Blob pattern,
                     long start)
              throws java.sql.SQLException

Determines the byte position in the BLOB value designated by this Blob object at which pattern begins. The search begins at position start.

Specified by:

position in interface java.sql.Blob

Parameters:

pattern - the Blob object designating the BLOB value for which to search

start - the position in the BLOB value at which to begin searching; the first position is 1

Returns:

the position at which the pattern begins, else -1

Throws:

java.sql.SQLException - if there is an error accessing the BLOB

Since:

1.2

See Also:

What Is in the JDBC 2.0 API

truncate

public void truncate(long param1)
              throws java.sql.SQLException

This operation is not currently supported Truncate this Blob to a given length.

Specified by:

truncate in interface java.sql.Blob

Parameters:

param1 - The length to truncate this Blob to

Throws:

java.sql.SQLException - this operation is not supported

setBytes

public int setBytes(long param1,
                    byte[] param2)
             throws java.sql.SQLException

This operation is not currently supported 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.

Specified by:

setBytes in interface java.sql.Blob

Parameters:

param1 - The position at which to start writing

param2 - The array of bytes to be written

Returns:

the number of bytes written

Throws:

java.sql.SQLException - because this operation is not supported

setBytes

public int setBytes(long param1,
                    byte[] param2,
                    int param3,
                    int param4)
             throws java.sql.SQLException

This operation is not currently supported 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.

Specified by:

setBytes in interface java.sql.Blob

Parameters:

param1 - The position at which to start writing

param2 - The array of bytes to be written

param3 - the offset into the byte array at which to start reading the bytes to be set

param4 - the number of bytes to be written to the BLOB value from the byte array

Returns:

the number of bytes written

Throws:

java.sql.SQLException - because this operation is not supported

setBinaryStream

public java.io.OutputStream setBinaryStream(long pos)
                                     throws java.sql.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.

Specified by:

setBinaryStream in interface java.sql.Blob

Specified by:

setBinaryStream in interface FirebirdBlob

Parameters:

pos - The position in the blob to start writing.

Returns:

OuputStream to write to.

Throws:

java.sql.SQLException - if a database access error occurs

getBlobId

public long getBlobId()
               throws java.sql.SQLException

Get the identifier for this Blob

Returns:

This Blob's identifier

Throws:

java.sql.SQLException - if a database access error occurs

copyBytes

public void copyBytes(byte[] bytes,
                      int pos,
                      int len)
               throws java.sql.SQLException

Throws:

java.sql.SQLException

copyStream

public void copyStream(java.io.InputStream inputStream,
                       int length)
                throws java.sql.SQLException

Copy the contents of an InputStream into this Blob.

Parameters:

inputStream - the stream from which data will be copied

length - The maximum number of bytes to read from the InputStream

Throws:

java.sql.SQLException - if a database access error occurs

copyStream

public void copyStream(java.io.InputStream inputStream)
                throws java.sql.SQLException

Copy the contents of an InputStream into this Blob. Unlike the copyStream(InputStream, int) method, this one copies bytes until the EOF is reached.

Parameters:

inputStream - the stream from which data will be copied

Throws:

java.sql.SQLException - if a database access error occurs

copyCharacterStream

public void copyCharacterStream(java.io.Reader inputStream,
                                int length,
                                java.lang.String encoding)
                         throws java.sql.SQLException

Copy data from a character stream into this Blob.

Parameters:

inputStream - the source of data to copy

length - The maximum number of bytes to copy

encoding - The encoding used in the character stream

Throws:

java.sql.SQLException