public
interface
Blob
| java.sql.Blob |
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. By default drivers implement 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. In addition, this interface has methods for updating
a BLOB value.
All methods on the Blob interface must be fully implemented if the
JDBC driver supports the data type.
Public methods | |
|---|---|
abstract
void
|
free()
This method frees the |
abstract
InputStream
|
getBinaryStream(long pos, long length)
Returns an |
abstract
InputStream
|
getBinaryStream()
Retrieves the |
abstract
byte[]
|
getBytes(long pos, int length)
Retrieves all or part of the |
abstract
long
|
length()
Returns the number of bytes in the |
abstract
long
|
position(Blob pattern, long start)
Retrieves the byte position in the |
abstract
long
|
position(byte[] pattern, long start)
Retrieves the byte position at which the specified byte array
|
abstract
OutputStream
|
setBinaryStream(long pos)
Retrieves a stream that can be used to write to the |
abstract
int
|
setBytes(long pos, byte[] bytes, int offset, int len)
Writes all or part of the given |
abstract
int
|
setBytes(long pos, byte[] bytes)
Writes the given array of bytes to the |
abstract
void
|
truncate(long len)
Truncates the |
void free ()
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.
| Throws | |
|---|---|
SQLException |
if an error occurs releasing the Blob's resources |
SQLFeatureNotSupportedException |
if the JDBC driver does not support this method |
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.
| Parameters | |
|---|---|
pos |
long:
the offset to the first byte of the partial value to be retrieved.
The first byte in the Blob is at position 1 |
length |
long:
the length in bytes of the partial value to be retrieved |
| Returns | |
|---|---|
InputStream |
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 |
SQLFeatureNotSupportedException |
if the JDBC driver does not support this method |
InputStream getBinaryStream ()
Retrieves the BLOB value designated by this
Blob instance as a stream.
| Returns | |
|---|---|
InputStream |
a stream containing the BLOB data |
| Throws | |
|---|---|
SQLException |
if there is an error accessing the
BLOB value |
SQLFeatureNotSupportedException |
if the JDBC driver does not support this method |
See also:
Developers
byte[] getBytes (long pos,
int length)
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.
| Parameters | |
|---|---|
pos |
long:
the ordinal position of the first byte in the
BLOB value to be extracted; the first byte is at
position 1 |
length |
int:
the number of consecutive bytes to be copied; the value
for length must be 0 or greater |
| Returns | |
|---|---|
byte[] |
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 | |
|---|---|
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 method |
See also:
long length ()
Returns the number of bytes in the BLOB value
designated by this Blob object.
| Returns | |
|---|---|
long |
length of the BLOB in bytes |
| Throws | |
|---|---|
SQLException |
if there is an error accessing the
length of the BLOB |
SQLFeatureNotSupportedException |
if the JDBC driver does not support this method |
long position (Blob pattern, long start)
Retrieves the byte position in the BLOB value
designated by this Blob object at which
pattern begins. The search begins at position
start.
| Parameters | |
|---|---|
pattern |
Blob:
the Blob object designating
the BLOB value for which to search |
start |
long:
the position in the BLOB value
at which to begin searching; the first position is 1 |
| Returns | |
|---|---|
long |
the position at which the pattern begins, else -1 |
| Throws | |
|---|---|
SQLException |
if there is an error accessing the
BLOB value or if start is less than 1 |
SQLFeatureNotSupportedException |
if the JDBC driver does not support this method |
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. The
search for pattern begins at position
start.
| Parameters | |
|---|---|
pattern |
byte:
the byte array for which to search |
start |
long:
the position at which to begin searching; the
first position is 1 |
| Returns | |
|---|---|
long |
the position at which the pattern appears, else -1 |
| Throws | |
|---|---|
SQLException |
if there is an error accessing the
BLOB or if start is less than 1 |
SQLFeatureNotSupportedException |
if the JDBC driver does not support this method |
OutputStream setBinaryStream (long pos)
Retrieves a stream that can be used to write to the 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.
| Parameters | |
|---|---|
pos |
long:
the position in the BLOB value at which
to start writing; the first position is 1 |
| Returns | |
|---|---|
OutputStream |
a java.io.OutputStream object to which data can
be written |
| Throws | |
|---|---|
SQLException |
if there is an error accessing the
BLOB value or if pos is less than 1 |
SQLFeatureNotSupportedException |
if the JDBC driver does not support this method |
See also:
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.
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.
| Parameters | |
|---|---|
pos |
long:
the position in the BLOB object at which
to start writing; the first position is 1 |
bytes |
byte:
the array of bytes to be written to this BLOB
object |
offset |
int:
the offset into the array bytes at which
to start reading the bytes to be set |
len |
int:
the number of bytes to be written to the BLOB
value from the array of bytes bytes |
| Returns | |
|---|---|
int |
the number of bytes written |
| Throws | |
|---|---|
SQLException |
if there is an error accessing the
BLOB value or if pos is less than 1 |
SQLFeatureNotSupportedException |
if the JDBC driver does not support this method |
See also:
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.
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.
| Parameters | |
|---|---|
pos |
long:
the position in the BLOB object at which
to start writing; the first position is 1 |
bytes |
byte:
the array of bytes to be written to the BLOB
value that this Blob object represents |
| Returns | |
|---|---|
int |
the number of bytes written |
| Throws | |
|---|---|
SQLException |
if there is an error accessing the
BLOB value or if pos is less than 1 |
SQLFeatureNotSupportedException |
if the JDBC driver does not support this method |
See also:
void truncate (long len)
Truncates the 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.
| Parameters | |
|---|---|
len |
long:
the length, in bytes, to which the BLOB value
that this Blob object represents should be truncated |
| Throws | |
|---|---|
SQLException |
if there is an error accessing the
BLOB value or if len is less than 0 |
SQLFeatureNotSupportedException |
if the JDBC driver does not support this method |