Package org.hsqldb.jdbc

Class jdbcBlob

java.lang.Object
org.hsqldb.jdbc.jdbcBlob
All Implemented Interfaces:
Blob
public class jdbcBlob extends Object implements Blob
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.

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.

Since:
JDK 1.2, HSQLDB 1.7.2
Author:
james house jhouse@part.net, boucherb@users

  • Constructor Summary

    Constructors
    Constructor
    Description
    jdbcBlob(byte[] data)
    Constructs a new jdbcBlob instance wrapping the given octet sequence.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    free()
     
    InputStream
    getBinaryStream()
    Retrieves the BLOB value designated by this Blob instance as a stream.
    InputStream
    getBinaryStream(long pos, long 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(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.
    long
    position(Blob pattern, long start)
    Retrieves the byte position in the BLOB value designated by this Blob object at which pattern begins.
    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 Details

    • 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.

      Parameters:
      data - the octet sequence representing the Blob value
      Throws:
      SQLException - if the argument is null

  • Method Details

    • length

      public long length() throws SQLException
      Returns the number of bytes in the BLOB value designated by this Blob object.
      Specified by:
      length in interface Blob
      Returns:
      length of the BLOB in bytes
      Throws:
      SQLException - if there is an error accessing the length of the BLOB
      Since:
      JDK 1.2, HSQLDB 1.7.2

    • 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.

      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.

      Specified by:
      getBytes in interface 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:
      SQLException - if there is an error accessing the BLOB value
      Since:
      JDK 1.2, HSQLDB 1.7.2
      See Also:

    • getBinaryStream

      public InputStream getBinaryStream() throws SQLException
      Retrieves the BLOB value designated by this Blob instance as a stream.
      Specified by:
      getBinaryStream in interface Blob
      Returns:
      a stream containing the BLOB data
      Throws:
      SQLException - if there is an error accessing the BLOB value
      Since:
      JDK 1.2, HSQLDB 1.7.2
      See Also:

    • 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.

      Specified by:
      position in interface 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:
      SQLException - if there is an error accessing the BLOB
      Since:
      JDK 1.2, HSQLDB 1.7.2

    • 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.
      Specified by:
      position in interface 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:
      SQLException - if there is an error accessing the BLOB value
      Since:
      JDK 1.2, HSQLDB 1.7.2

    • 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.

      HSQLDB-Specific Information:

      HSLQDB 1.7.2 does not support this feature.

      Calling this method always throws an SQLException.

      Specified by:
      setBytes in interface Blob
      Parameters:
      pos - the position in the BLOB object at which to start writing
      bytes - the array of bytes to be written to the BLOB value that this Blob object represents
      Returns:
      the number of bytes written
      Throws:
      SQLException - if there is an error accessing the BLOB value
      Since:
      JDK 1.4, HSQLDB 1.7.2
      See Also:

    • 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.

      HSQLDB-Specific Information:

      HSLQDB 1.7.2 does not support this feature.

      Calling this method always throws an SQLException.

      Specified by:
      setBytes in interface Blob
      Parameters:
      pos - the position in the BLOB object at which to start writing
      bytes - the array of bytes to be written to this BLOB object
      offset - the offset into the array bytes at which to start reading the bytes to be set
      len - the number of bytes to be written to the BLOB value from the array of bytes bytes
      Returns:
      the number of bytes written
      Throws:
      SQLException - if there is an error accessing the BLOB value
      Since:
      JDK 1.4, HSQLDB 1.7.2
      See Also:

    • 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.

      HSQLDB-Specific Information:

      HSQLDB 1.7.2 does not support this feature.

      Calling this method always throws an SQLException.

      Specified by:
      setBinaryStream in interface Blob
      Parameters:
      pos - the position in the BLOB value at which to start writing
      Returns:
      a java.io.OutputStream object to which data can be written
      Throws:
      SQLException - if there is an error accessing the BLOB value
      Since:
      JDK 1.4, HSQLDB 1.7.2
      See Also:

    • truncate

      public void truncate(long len) throws SQLException
      Truncates the BLOB value that this Blob object represents to be len bytes in length.

      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.

      Specified by:
      truncate in interface Blob
      Parameters:
      len - 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
      Since:
      JDK 1.4, HSQLDB 1.7.2

    • free

      public void free() throws SQLException
      Specified by:
      free in interface Blob
      Throws:
      SQLException

    • getBinaryStream

      public InputStream getBinaryStream(long pos, long length) throws SQLException
      Specified by:
      getBinaryStream in interface Blob
      Throws:
      SQLException