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java.lang.Object org.hsqldb.jdbc.jdbcBlob
The representation (mapping) in the JavaTM 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.
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.
Constructor Summary | |
jdbcBlob(byte[] data)
Constructs a new jdbcBlob instance wrapping the given octet sequence. |
Method Summary | |
java.io.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(java.sql.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. |
Methods inherited from class java.lang.Object |
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
public jdbcBlob(byte[] data) throws java.sql.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 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
java.sql.SQLException
- if the argument is nullMethod Detail |
public long length() throws java.sql.SQLException
BLOB
value
designated by this Blob
object.
length
in interface java.sql.Blob
BLOB
in bytes
java.sql.SQLException
- if there is an error accessing the
length of the BLOB
public byte[] getBytes(long pos, int length) throws java.sql.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 later policy.
getBytes
in interface java.sql.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 copied
length
consecutive bytes from the BLOB
value designated
by this Blob
object, starting with the
byte at position pos
java.sql.SQLException
- if there is an error accessing the
BLOB
valuesetBytes(long, byte[])
public java.io.InputStream getBinaryStream() throws java.sql.SQLException
BLOB
value designated by this
Blob
instance as a stream.
getBinaryStream
in interface java.sql.Blob
BLOB
data
java.sql.SQLException
- if there is an error accessing the
BLOB
valuesetBinaryStream(long)
public long position(byte[] pattern, long start) throws java.sql.SQLException
pattern
begins within the BLOB
value that this Blob
object represents. The
search for pattern
begins at position
start
.
position
in interface java.sql.Blob
pattern
- the byte array for which to searchstart
- the position at which to begin searching; the
first position is 1
java.sql.SQLException
- if there is an error accessing the
BLOB
public long position(java.sql.Blob pattern, long start) throws java.sql.SQLException
BLOB
value
designated by this Blob
object at which
pattern
begins. The search begins at position
start
.
position
in interface java.sql.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 1
java.sql.SQLException
- if there is an error accessing the
BLOB
valuepublic int setBytes(long pos, byte[] bytes) throws java.sql.SQLException
BLOB
value that
this Blob
object represents, starting at position
pos
, and returns the number of bytes written.
HSLQDB 1.7.2 does not support this feature.
Calling this method always throws an SQLException
.
setBytes
in interface java.sql.Blob
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
java.sql.SQLException
- if there is an error accessing the
BLOB
valuegetBytes(long, int)
public int setBytes(long pos, byte[] bytes, int offset, int len) throws java.sql.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.
HSLQDB 1.7.2 does not support this feature.
Calling this method always throws an SQLException
.
setBytes
in interface java.sql.Blob
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
java.sql.SQLException
- if there is an error accessing the
BLOB
valuegetBytes(long, int)
public java.io.OutputStream setBinaryStream(long pos) throws java.sql.SQLException
BLOB
value that this Blob
object represents. The stream begins
at position pos
.
HSQLDB 1.7.2 does not support this feature.
Calling this method always throws an SQLException
.
setBinaryStream
in interface java.sql.Blob
pos
- the position in the BLOB
value at which
to start writing
java.io.OutputStream
object to which data can
be written
java.sql.SQLException
- if there is an error accessing the
BLOB
valuegetBinaryStream()
public void truncate(long len) throws java.sql.SQLException
BLOB
value that this Blob
object represents to be len
bytes in length.
This operation affects only the client-side value; it has no effect upon the value as it is stored in the database.
truncate
in interface java.sql.Blob
len
- the length, in bytes, to which the BLOB
value
that this Blob
object represents should be truncated
java.sql.SQLException
- if there is an error accessing the
BLOB
value
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