Class jdbcClob

java.lang.Object
org.hsqldb.jdbc.jdbcClob
All Implemented Interfaces:
Clob

public final class jdbcClob extends Object implements Clob
The mapping in the JavaTM programming language for the SQL CLOB type.

Provides methods for getting the length of an SQL CLOB (Character Large Object) value, for materializing a CLOB value on the client, and for searching for a substring or CLOB object within a CLOB value.

HSQLDB-Specific Information:

Including 1.8.x, the HSQLDB driver does not implement Clob using an SQL locator(CLOB). That is, an HSQLDB Clob object does not contain a logical pointer to SQL CLOB data; rather it directly contains an immutable representation of the data (a String object). As a result, an HSQLDB Clob object itself is 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 CLOB value are unsupported. However, the truncate method is supported for local use.

Since:
JDK 1.2, HSQLDB 1.7.2
Author:
boucherb@users
  • Constructor Summary

    Constructors
    Constructor
    Description
    Constructs a new jdbcClob object wrapping the given character sequence.
  • Method Summary

    Modifier and Type
    Method
    Description
    void
     
    Retrieves the CLOB value designated by this Clob object as an ascii stream.
    Retrieves the CLOB value designated by this Clob object as a java.io.Reader object (or as a stream of characters).
    getCharacterStream(long pos, long length)
     
    getSubString(long pos, int length)
    Retrieves a copy of the specified substring in the CLOB value designated by this Clob object.
    long
    Retrieves the number of characters in the CLOB value designated by this Clob object.
    long
    position(String searchstr, long start)
    Retrieves the character position at which the specified substring searchstr appears in the SQL CLOB value represented by this Clob object.
    long
    position(Clob searchstr, long start)
    Retrieves the character position at which the specified Clob object searchstr appears in this Clob object.
    setAsciiStream(long pos)
    Retrieves a stream to be used to write Ascii characters to the CLOB value that this Clob object represents, starting at position pos.
    Retrieves a stream to be used to write a stream of Unicode characters to the CLOB value that this Clob object represents, at position pos.
    int
    setString(long pos, String str)
    Writes the given Java String to the CLOB value that this Clob object designates at the position pos.
    int
    setString(long pos, String str, int offset, int len)
    Writes len characters of str, starting at character offset, to the CLOB value that this Clob represents.
    void
    truncate(long len)
    Truncates the CLOB value that this Clob designates to have a length of len characters.

    Methods inherited from class java.lang.Object

    equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
  • Constructor Details

    • jdbcClob

      public jdbcClob(String data) throws SQLException
      Constructs a new jdbcClob object wrapping the given character sequence.

      This constructor is used internally to retrieve result set values as Clob 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 String object rather than making a copy and so it is gently suggested (in the interest of effective memory management) that extenal clients using this constructor either take pause to consider the implications or at least take care to provide a String object whose internal character buffer is not much larger than required to represent the value.

      Parameters:
      data - the character sequence representing the Clob value
      Throws:
      SQLException - if the argument is null
  • Method Details

    • length

      public long length() throws SQLException
      Retrieves the number of characters in the CLOB value designated by this Clob object.
      Specified by:
      length in interface Clob
      Returns:
      length of the CLOB in characters
      Throws:
      SQLException - if there is an error accessing the length of the CLOB value
      Since:
      JDK 1.2, HSQLDB 1.7.2
    • getSubString

      public String getSubString(long pos, int length) throws SQLException
      Retrieves a copy of the specified substring in the CLOB value designated by this Clob object. The substring begins at position pos and has up to length consecutive characters.

      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 characters from pos to this.length(). Another would be to throw an exception. HSQLDB observes the later policy.

      Specified by:
      getSubString in interface Clob
      Parameters:
      pos - the first character of the substring to be extracted. The first character is at position 1.
      length - the number of consecutive characters to be copied
      Returns:
      a String that is the specified substring in the CLOB value designated by this Clob object
      Throws:
      SQLException - if there is an error accessing the CLOB value
      Since:
      JDK 1.2, HSQLDB 1.7.2
    • getCharacterStream

      public Reader getCharacterStream() throws SQLException
      Retrieves the CLOB value designated by this Clob object as a java.io.Reader object (or as a stream of characters).
      Specified by:
      getCharacterStream in interface Clob
      Returns:
      a java.io.Reader object containing the CLOB data
      Throws:
      SQLException - if there is an error accessing the CLOB value
      Since:
      JDK 1.2, HSQLDB 1.7.2
      See Also:
    • getAsciiStream

      public InputStream getAsciiStream() throws SQLException
      Retrieves the CLOB value designated by this Clob object as an ascii stream.
      Specified by:
      getAsciiStream in interface Clob
      Returns:
      a java.io.InputStream object containing the CLOB data
      Throws:
      SQLException - if there is an error accessing the CLOB value
      Since:
      JDK 1.2, HSQLDB 1.7.2
      See Also:
    • position

      public long position(String searchstr, long start) throws SQLException
      Retrieves the character position at which the specified substring searchstr appears in the SQL CLOB value represented by this Clob object. The search begins at position start.
      Specified by:
      position in interface Clob
      Parameters:
      searchstr - the substring for which to search
      start - the position at which to begin searching; the first position is 1
      Returns:
      the position at which the substring appears or -1 if it is not present; the first position is 1
      Throws:
      SQLException - if there is an error accessing the CLOB value
      Since:
      JDK 1.2, HSQLDB 1.7.2
    • position

      public long position(Clob searchstr, long start) throws SQLException
      Retrieves the character position at which the specified Clob object searchstr appears in this Clob object. The search begins at position start.
      Specified by:
      position in interface Clob
      Parameters:
      searchstr - the Clob object for which to search
      start - the position at which to begin searching; the first position is 1
      Returns:
      the position at which the Clob object appears or -1 if it is not present; the first position is 1
      Throws:
      SQLException - if there is an error accessing the CLOB value
      Since:
      JDK 1.2, HSQLDB 1.7.2
    • setString

      public int setString(long pos, String str) throws SQLException
      Writes the given Java String to the CLOB value that this Clob object designates at the position pos.

      HSQLDB-Specific Information:

      HSLQDB 1.7.2 does not support this feature.

      Calling this method always throws an SQLException.

      Specified by:
      setString in interface Clob
      Parameters:
      pos - the position at which to start writing to the CLOB value that this Clob object represents
      str - the string to be written to the CLOB value that this Clob designates
      Returns:
      the number of characters written
      Throws:
      SQLException - if there is an error accessing the CLOB value
      Since:
      JDK 1.4, HSQLDB 1.7.2
    • setString

      public int setString(long pos, String str, int offset, int len) throws SQLException
      Writes len characters of str, starting at character offset, to the CLOB value that this Clob represents.

      HSQLDB-Specific Information:

      HSLQDB 1.7.2 does not support this feature.

      Calling this method always throws an SQLException.

      Specified by:
      setString in interface Clob
      Parameters:
      pos - the position at which to start writing to this CLOB object
      str - the string to be written to the CLOB value that this Clob object represents
      offset - the offset into str to start reading the characters to be written
      len - the number of characters to be written
      Returns:
      the number of characters written
      Throws:
      SQLException - if there is an error accessing the CLOB value
      Since:
      JDK 1.4, HSQLDB 1.7.2
    • setAsciiStream

      public OutputStream setAsciiStream(long pos) throws SQLException
      Retrieves a stream to be used to write Ascii characters to the CLOB value that this Clob object represents, starting at position pos.

      HSQLDB-Specific Information:

      HSLQDB 1.7.2 does not support this feature.

      Calling this method always throws an SQLException.

      Specified by:
      setAsciiStream in interface Clob
      Parameters:
      pos - the position at which to start writing to this CLOB object
      Returns:
      the stream to which ASCII encoded characters can be written
      Throws:
      SQLException - if there is an error accessing the CLOB value
      Since:
      JDK 1.4, HSQLDB 1.7.2
      See Also:
    • setCharacterStream

      public Writer setCharacterStream(long pos) throws SQLException
      Retrieves a stream to be used to write a stream of Unicode characters to the CLOB value that this Clob object represents, at position pos.

      HSQLDB-Specific Information:

      HSLQDB 1.7.2 does not support this feature.

      Calling this method always throws an SQLException.

      Specified by:
      setCharacterStream in interface Clob
      Parameters:
      pos - the position at which to start writing to the CLOB value
      Returns:
      a stream to which Unicode encoded characters can be written
      Throws:
      SQLException - if there is an error accessing the CLOB value
      Since:
      JDK 1.4, HSQLDB 1.7.2
      See Also:
    • truncate

      public void truncate(long len) throws SQLException
      Truncates the CLOB value that this Clob designates to have a length of len characters.

      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 Clob
      Parameters:
      len - the length, in bytes, to which the CLOB value should be truncated
      Throws:
      SQLException - if there is an error accessing the CLOB value
      Since:
      JDK 1.4, HSQLDB 1.7.2
    • free

      public void free() throws SQLException
      Specified by:
      free in interface Clob
      Throws:
      SQLException
    • getCharacterStream

      public Reader getCharacterStream(long pos, long length) throws SQLException
      Specified by:
      getCharacterStream in interface Clob
      Throws:
      SQLException