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 Java^TM 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
jdbcClob(String data)	Constructs a new jdbcClob object wrapping the given character sequence.

Method Summary

Modifier and Type	Method	Description
void	free()
InputStream	getAsciiStream()	Retrieves the CLOB value designated by this Clob object as an ascii stream.
Reader	getCharacterStream()	Retrieves the CLOB value designated by this Clob object as a java.io.Reader object (or as a stream of characters).
Reader	getCharacterStream(long pos, long length)
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(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.
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.
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, 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 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:

• setCharacterStream(long)

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:

• setAsciiStream(long)

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:

• getAsciiStream()

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:

• getCharacterStream()

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