Modifier and Type | Field and Description |
---|---|
static long |
MAX_POS |
static long |
MIN_POS |
Constructor and Description |
---|
JDBCBlob(byte[] data)
Constructs a new JDBCBlob instance wrapping the given octet sequence.
|
Modifier and Type | Method and Description |
---|---|
void |
free()
This method frees the
Blob object and releases the resources that
it holds. |
java.io.InputStream |
getBinaryStream()
Retrieves the
BLOB value 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. |
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. |
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 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. |
public static final long MIN_POS
public static final long MAX_POS
public JDBCBlob(byte[] data) throws SQLException
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 external clients never to use this constructor with a byte array object that may later be modified externally.
data
- the octet sequence representing the Blob valueSQLException
- if the argument is nullpublic long length() throws SQLException
BLOB
value
designated by this Blob
object.length
in interface Blob
BLOB
in bytesSQLException
- if there is an error accessing the
length of the BLOB
SQLFeatureNotSupportedException
- if the JDBC driver does not support
this methodpublic byte[] getBytes(long pos, int length) throws SQLException
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
.
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 second policy.
getBytes
in interface Blob
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 copiedlength
consecutive bytes from the BLOB
value designated
by this Blob
object, starting with the
byte at position pos
SQLException
- if there is an error accessing the BLOB value;
if pos
is less than 1 or length
is
less than 0.SQLFeatureNotSupportedException
- if the JDBC driver does not support
this methodsetBytes(long, byte[])
public java.io.InputStream getBinaryStream() throws SQLException
BLOB
value designated by this
Blob
instance as a stream.getBinaryStream
in interface Blob
BLOB
dataSQLException
- if there is an error accessing the
BLOB
valueSQLFeatureNotSupportedException
- if the JDBC driver does not support
this methodsetBinaryStream(long)
public long position(byte[] pattern, long start) throws SQLException
pattern
begins within the BLOB
value that this Blob
object represents. The
search for pattern
begins at position
start
.position
in interface Blob
pattern
- the byte array for which to searchstart
- the position at which to begin searching; the
first position is 1SQLException
- if there is an error accessing the
BLOB
or if start is less than 1SQLFeatureNotSupportedException
- if the JDBC driver does not support
this methodpublic long position(Blob pattern, long start) throws SQLException
BLOB
value
designated by this Blob
object at which
pattern
begins. The search begins at position
start
.position
in interface Blob
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 1SQLException
- if there is an error accessing the
BLOB
value or if start is less than 1SQLFeatureNotSupportedException
- if the JDBC driver does not support
this methodpublic int setBytes(long pos, byte[] bytes) throws SQLException
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 accomodate the extra bytes.
Note: If the value specified for pos
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.
Starting with HSQLDB 2.0 this feature is supported.
When built under JDK 1.6+ and the Blob instance is constructed as a result of calling JDBCConnection.createBlob(), this operation affects only the client-side value; it has no effect upon a value stored in a database because JDBCConnection.createBlob() constructs disconnected, initially empty Blob instances. To propogate the Blob value to a database in this case, it is required to supply the Blob instance to an updating or inserting setXXX method of a Prepared or Callable Statement, or to supply the Blob instance to an updateXXX method of an updateable ResultSet.
Implementation Notes:
No attempt is made to ensure precise thread safety. Instead, volatile member field and local variable snapshot isolation semantics are implemented. This is expected to eliminate most issues related to race conditions, with the possible exception of concurrent invocation of free().
In general, however, if an application may perform concurrent JDBCBlob modifications and the integrity of the application depends on total order Blob modification semantics, then such operations should be synchronized on an appropriate monitor.
setBytes
in interface Blob
pos
- the position in the BLOB
object at which
to start writing; the first position is 1bytes
- the array of bytes to be written to the BLOB
value that this Blob
object representsSQLException
- if there is an error accessing the
BLOB
value or if pos is less than 1SQLFeatureNotSupportedException
- if the JDBC driver does not support
this methodgetBytes(long, int)
public int setBytes(long pos, byte[] bytes, int offset, int len) throws SQLException
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 accomodate the extra bytes.
Note: If the value specified for pos
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.
Starting with HSQLDB 2.0 this feature is supported.
When built under JDK 1.6+ and the Blob instance is constructed as a result of calling JDBCConnection.createBlob(), this operation affects only the client-side value; it has no effect upon a value stored in a database because JDBCConnection.createBlob() constructs disconnected, initially empty Blob instances. To propogate the Blob value to a database in this case, it is required to supply the Blob instance to an updating or inserting setXXX method of a Prepared or Callable Statement, or to supply the Blob instance to an updateXXX method of an updateable ResultSet.
Implementation Notes:
If the value specified for pos
is greater than the length of the BLOB
value, then
the BLOB
value is extended in length to accept the
written octets and the undefined region up to pos
is
filled with (byte)0.
No attempt is made to ensure precise thread safety. Instead, volatile member field and local variable snapshot isolation semantics are implemented. This is expected to eliminate most issues related to race conditions, with the possible exception of concurrent invocation of free().
In general, however, if an application may perform concurrent JDBCBlob modifications and the integrity of the application depends on total order Blob modification semantics, then such operations should be synchronized on an appropriate monitor.
setBytes
in interface Blob
pos
- the position in the BLOB
object at which
to start writing; the first position is 1bytes
- 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
SQLException
- if there is an error accessing the
BLOB
value or if pos is less than 1SQLFeatureNotSupportedException
- if the JDBC driver does not support
this methodgetBytes(long, int)
public java.io.OutputStream setBinaryStream(long pos) throws SQLException
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 accomodate the extra bytes.
Note: If the value specified for pos
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.
Starting with HSQLDB 2.0 this feature is supported.
When built under JDK 1.6+ and the Blob instance is constructed as a result of calling JDBCConnection.createBlob(), this operation affects only the client-side value; it has no effect upon a value stored in a database because JDBCConnection.createBlob() constructs disconnected, initially empty Blob instances. To propogate the Blob value to a database in this case, it is required to supply the Blob instance to an updating or inserting setXXX method of a Prepared or Callable Statement, or to supply the Blob instance to an updateXXX method of an updateable ResultSet.
Implementation Notes:
The data written to the stream does not appear in this Blob until the stream is closed
When the stream is closed, if the value specified for pos
is greater than the length of the BLOB
value, then
the BLOB
value is extended in length to accept the
written octets and the undefined region up to pos
is
filled with (byte)0.
Also, no attempt is made to ensure precise thread safety. Instead, volatile member field and local variable snapshot isolation semantics are implemented. This is expected to eliminate most issues related to race conditions, with the possible exception of concurrent invocation of free().
In general, however, if an application may perform concurrent JDBCBlob modifications and the integrity of the application depends on total order Blob modification semantics, then such operations should be synchronized on an appropriate monitor.
setBinaryStream
in interface Blob
pos
- the position in the BLOB
value at which
to start writing; the first position is 1java.io.OutputStream
object to which data can
be writtenSQLException
- if there is an error accessing the
BLOB
value or if pos is less than 1SQLFeatureNotSupportedException
- if the JDBC driver does not support
this methodgetBinaryStream()
public void truncate(long len) throws SQLException
BLOB
value that this Blob
object represents to be len
bytes in length.
Note: If the value specified for pos
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.
Starting with HSQLDB 2.0 this feature is fully supported.
When built under JDK 1.6+ and the Blob instance is constructed as a result of calling JDBCConnection.createBlob(), this operation affects only the client-side value; it has no effect upon a value stored in a database because JDBCConnection.createBlob() constructs disconnected, initially empty Blob instances. To propogate the truncated Blob value to a database in this case, it is required to supply the Blob instance to an updating or inserting setXXX method of a Prepared or Callable Statement, or to supply the Blob instance to an updateXXX method of an updateable ResultSet.
truncate
in interface Blob
len
- the length, in bytes, to which the BLOB
value
that this Blob
object represents should be truncatedSQLException
- if there is an error accessing the
BLOB
value or if len is less than 0SQLFeatureNotSupportedException
- if the JDBC driver does not support
this methodpublic void free() throws SQLException
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.
free
in interface Blob
SQLException
- if an error occurs releasing
the Blob's resourcesSQLFeatureNotSupportedException
- if the JDBC driver does not support
this methodpublic java.io.InputStream getBinaryStream(long pos, long length) throws SQLException
InputStream
object that contains a partial Blob
value,
starting with the byte specified by pos, which is length bytes in length.getBinaryStream
in interface Blob
pos
- the offset to the first byte of the partial value to be retrieved.
The first byte in the Blob
is at position 1length
- the length in bytes of the partial value to be retrievedInputStream
through which the partial Blob
value can be read.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
SQLFeatureNotSupportedException
- if the JDBC driver does not support
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