org.hsqldb.jdbc
Class jdbcBlob
- Blob
public class jdbcBlob
extends java.lang.Object
implements Blob
The representation (mapping) in the Java
TM
programming language of an SQL BLOB value.
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 an octet sequence (byte pattern) within a BLOB value.
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HSQLDB-Specific Information:
Including 1.8.x, the HSQLDB driver does not implement Blob using an SQL
locator(BLOB). That is, an HSQLDB Blob object does not contain a logical
pointer to SQL BLOB data; rather it directly contains a representation of
the data (a byte array). As a result, an HSQLDB Blob object is itself
valid beyond the duration of the transaction in which is was created,
although it does not necessarily represent a corresponding value
on the database.
Currently, the interface methods for updating a BLOB value are
unsupported. However, the truncate method is supported for local use.
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- james house jhouse@part.net
- boucherb@users
jdbcBlob(byte[] data) - Constructs a new jdbcBlob instance wrapping the given octet sequence.
|
InputStream | getBinaryStream() - Retrieves the
BLOB value designated by this
Blob instance as a stream.
|
byte[] | getBytes(long pos, int length) - Retrieves all or part of the
BLOB value that this
Blob object represents, as an array of bytes.
|
long | length() - Returns the number of bytes in the
BLOB value
designated by this Blob object.
|
long | position(Blob pattern, long start) - Retrieves the byte position in the
BLOB value
designated by this Blob object at which
pattern begins.
|
long | position(byte[] pattern, long start) - Retrieves the byte position at which the specified byte array
pattern begins within the BLOB
value that this Blob object represents.
|
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 len) - 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 len) - Truncates the
BLOB value that this Blob
object represents to be len bytes in length.
|
jdbcBlob
public jdbcBlob(byte[] data)
throws SQLException
Constructs a new jdbcBlob instance wrapping the given octet sequence.
This constructor is used internally to retrieve result set values as
Blob objects, yet it must be public to allow access from other packages.
As such (in the interest of efficiency) this object maintains a reference
to the given octet sequence rather than making a copy; special care
should be taken by extenal clients never to use this constructor with a
byte array object that may later be modified extenally.
data
- the octet sequence representing the Blob value
getBinaryStream
public InputStream getBinaryStream()
throws SQLException
Retrieves the BLOB
value designated by this
Blob
instance as a stream.
- a stream containing the
BLOB
data
getBytes
public 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
.
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HSQLDB-Specific Information:
The official specification above is ambiguous in that it does not
precisely indicate the policy to be observed when
pos > this.length() - length. One policy would be to retrieve the
octets from pos to this.length(). Another would be to throw an
exception. HSQLDB observes the later policy.
pos
- the ordinal position of the first byte in the
BLOB
value to be extracted; the first byte is at
position 1length
- the number of consecutive bytes to be copied
- 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
length
public long length()
throws SQLException
Returns the number of bytes in the BLOB
value
designated by this Blob
object.
- length of the
BLOB
in bytes
position
public 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
.
pattern
- the Blob
object designating
the BLOB
value for which to searchstart
- the position in the BLOB
value
at which to begin searching; the first position is 1
- the position at which the pattern begins, else -1
position
public 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
.
pattern
- the byte array for which to searchstart
- the position at which to begin searching; the
first position is 1
- the position at which the pattern appears, else -1
setBinaryStream
public 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
.
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HSQLDB-Specific Information:
HSQLDB 1.7.2 does not support this feature.
Calling this method always throws an
SQLException
.
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pos
- the position in the BLOB
value at which
to start writing
- a
java.io.OutputStream
object to which data can
be written
setBytes
public 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.
<!-- start release-specific documentation -->
HSQLDB-Specific Information:
HSLQDB 1.7.2 does not support this feature.
Calling this method always throws an
SQLException
.
<!-- end release-specific documentation -->
pos
- the position in the BLOB
object at which
to start writingbytes
- the array of bytes to be written to the BLOB
value that this Blob
object represents
- the number of bytes written
setBytes
public 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.
<!-- start release-specific documentation -->
HSQLDB-Specific Information:
HSLQDB 1.7.2 does not support this feature.
Calling this method always throws an
SQLException
.
<!-- end release-specific documentation -->
pos
- the position in the BLOB
object at which
to start writingbytes
- the array of bytes to be written to this BLOB
objectoffset
- the offset into the array bytes
at which
to start reading the bytes to be setlen
- the number of bytes to be written to the BLOB
value from the array of bytes bytes
- the number of bytes written
truncate
public void truncate(long len)
throws SQLException
Truncates the
BLOB
value that this
Blob
object represents to be
len
bytes in length.
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HSQLDB-Specific Information:
This operation affects only the client-side value; it has no effect upon
the value as it is stored in the database.
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len
- the length, in bytes, to which the BLOB
value
that this Blob
object represents should be truncated
Copyright B) 2001 - 2005 HSQL Development Group. All Rights Reserved.