org.hsqldb.jdbc
Class jdbcClob

java.lang.Object
  extended byorg.hsqldb.jdbc.jdbcClob
All Implemented Interfaces:
java.sql.Clob

public final class jdbcClob
extends java.lang.Object
implements java.sql.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 1.7.2, 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
jdbcClob(java.lang.String data)
          Constructs a new jdbcClob object wrapping the given character sequence.
 
Method Summary
 java.io.InputStream getAsciiStream()
          Retrieves the CLOB value designated by this Clob object as an ascii stream.
 java.io.Reader getCharacterStream()
          Retrieves the CLOB value designated by this Clob object as a java.io.Reader object (or as a stream of characters).
 java.lang.String getSubString(long pos, int length)
          Retrieves a copy of the specified substring in the CLOB value designated by this Clob object.
 long length()
          Retrieves the number of characters in the CLOB value designated by this Clob object.
 long position(java.sql.Clob searchstr, long start)
          Retrieves the character position at which the specified Clob object searchstr appears in this Clob object.
 long position(java.lang.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.
 java.io.OutputStream 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.
 java.io.Writer setCharacterStream(long 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, java.lang.String str)
          Writes the given Java String to the CLOB value that this Clob object designates at the position pos.
 int setString(long pos, java.lang.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 Detail

jdbcClob

public jdbcClob(java.lang.String data)
         throws java.sql.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:
java.sql.SQLException - if the argument is null
Method Detail

length

public long length()
            throws java.sql.SQLException
Retrieves the number of characters in the CLOB value designated by this Clob object.

Specified by:
length in interface java.sql.Clob
Returns:
length of the CLOB in characters
Throws:
java.sql.SQLException - if there is an error accessing the length of the CLOB value
Since:
JDK 1.2, HSQLDB 1.7.2

getSubString

public java.lang.String getSubString(long pos,
                                     int length)
                              throws java.sql.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 java.sql.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:
java.sql.SQLException - if there is an error accessing the CLOB value
Since:
JDK 1.2, HSQLDB 1.7.2

getCharacterStream

public java.io.Reader getCharacterStream()
                                  throws java.sql.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 java.sql.Clob
Returns:
a java.io.Reader object containing the CLOB data
Throws:
java.sql.SQLException - if there is an error accessing the CLOB value
Since:
JDK 1.2, HSQLDB 1.7.2
See Also:
setCharacterStream(long)

getAsciiStream

public java.io.InputStream getAsciiStream()
                                   throws java.sql.SQLException
Retrieves the CLOB value designated by this Clob object as an ascii stream.

Specified by:
getAsciiStream in interface java.sql.Clob
Returns:
a java.io.InputStream object containing the CLOB data
Throws:
java.sql.SQLException - if there is an error accessing the CLOB value
Since:
JDK 1.2, HSQLDB 1.7.2
See Also:
setAsciiStream(long)

position

public long position(java.lang.String searchstr,
                     long start)
              throws java.sql.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 java.sql.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:
java.sql.SQLException - if there is an error accessing the CLOB value
Since:
JDK 1.2, HSQLDB 1.7.2

position

public long position(java.sql.Clob searchstr,
                     long start)
              throws java.sql.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 java.sql.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:
java.sql.SQLException - if there is an error accessing the CLOB value
Since:
JDK 1.2, HSQLDB 1.7.2

setString

public int setString(long pos,
                     java.lang.String str)
              throws java.sql.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 java.sql.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:
java.sql.SQLException - if there is an error accessing the CLOB value
Since:
JDK 1.4, HSQLDB 1.7.2

setString

public int setString(long pos,
                     java.lang.String str,
                     int offset,
                     int len)
              throws java.sql.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 java.sql.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:
java.sql.SQLException - if there is an error accessing the CLOB value
Since:
JDK 1.4, HSQLDB 1.7.2

setAsciiStream

public java.io.OutputStream setAsciiStream(long pos)
                                    throws java.sql.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 java.sql.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:
java.sql.SQLException - if there is an error accessing the CLOB value
Since:
JDK 1.4, HSQLDB 1.7.2
See Also:
getAsciiStream()

setCharacterStream

public java.io.Writer setCharacterStream(long pos)
                                  throws java.sql.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 java.sql.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:
java.sql.SQLException - if there is an error accessing the CLOB value
Since:
JDK 1.4, HSQLDB 1.7.2
See Also:
getCharacterStream()

truncate

public void truncate(long len)
              throws java.sql.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 java.sql.Clob
Parameters:
len - the length, in bytes, to which the CLOB value should be truncated
Throws:
java.sql.SQLException - if there is an error accessing the CLOB value
Since:
JDK 1.4, HSQLDB 1.7.2


Copyright 2001 - 2004 HSQL Development Group. All Rights Reserved.