程序包 java.sql

接口 Clob

所有已知子接口:

NClob

所有已知实现类:

Clob

public interface Clob

The mapping in the Java™ programming language for the SQL CLOB type. An SQL CLOB is a built-in type that stores a Character Large Object as a column value in a row of a database table. By default drivers implement a Clob object using an SQL locator(CLOB), which means that a Clob object contains a logical pointer to the SQL CLOB data rather than the data itself. A Clob object is valid for the duration of the transaction in which it was created.

The Clob interface 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. Methods in the interfaces ResultSet, CallableStatement, and PreparedStatement, such as getClob and setClob allow a programmer to access an SQL CLOB value. In addition, this interface has methods for updating a CLOB value.

All methods on the Clob interface must be fully implemented if the JDBC driver supports the data type.

从以下版本开始:

1.2

方法概要

限定符和类型	方法	说明
void	free()	This method frees the Clob object and releases the resources the resources that it holds.
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)	Returns a Reader object that contains a partial Clob value, starting with the character specified by pos, which is length characters in 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.

方法详细资料

length

long length()
     throws SQLException

Retrieves the number of characters in the CLOB value designated by this Clob object.

返回:

length of the CLOB in characters

抛出:

SQLException - if there is an error accessing the length of the CLOB value

SQLFeatureNotSupportedException - if the JDBC driver does not support this method

从以下版本开始:

1.2

getSubString

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.

参数:

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; the value for length must be 0 or greater

返回:

a String that is the specified substring in the CLOB value designated by this Clob object

抛出:

SQLException - if there is an error accessing the CLOB value; if pos is less than 1 or length is less than 0

SQLFeatureNotSupportedException - if the JDBC driver does not support this method

从以下版本开始:

1.2

getCharacterStream

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).

返回:

a java.io.Reader object containing the CLOB data

抛出:

SQLException - if there is an error accessing the CLOB value

SQLFeatureNotSupportedException - if the JDBC driver does not support this method

从以下版本开始:

1.2

另请参阅:

setCharacterStream(long)

getAsciiStream

InputStream getAsciiStream()
                    throws SQLException

Retrieves the CLOB value designated by this Clob object as an ascii stream.

返回:

a java.io.InputStream object containing the CLOB data

抛出:

SQLException - if there is an error accessing the CLOB value

SQLFeatureNotSupportedException - if the JDBC driver does not support this method

从以下版本开始:

1.2

另请参阅:

setAsciiStream(long)

position

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.

参数:

searchstr - the substring for which to search

start - the position at which to begin searching; the first position is 1

返回:

the position at which the substring appears or -1 if it is not present; the first position is 1

抛出:

SQLException - if there is an error accessing the CLOB value or if pos is less than 1

SQLFeatureNotSupportedException - if the JDBC driver does not support this method

从以下版本开始:

1.2

position

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.

参数:

searchstr - the Clob object for which to search

start - the position at which to begin searching; the first position is 1

返回:

the position at which the Clob object appears or -1 if it is not present; the first position is 1

抛出:

SQLException - if there is an error accessing the CLOB value or if start is less than 1

SQLFeatureNotSupportedException - if the JDBC driver does not support this method

从以下版本开始:

1.2

setString

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. The string will overwrite the existing characters in the Clob object starting at the position pos. If the end of the Clob value is reached while writing the given string, then the length of the Clob value will be increased to accommodate the extra characters.

Note: If the value specified for pos is greater then the length+1 of the CLOB value then the behavior is undefined. Some JDBC drivers may throw a SQLException while other drivers may support this operation.

参数:

pos - the position at which to start writing to the CLOB value that this Clob object represents; The first position is 1

str - the string to be written to the CLOB value that this Clob designates

返回:

the number of characters written

抛出:

SQLException - if there is an error accessing the CLOB value or if pos is less than 1

SQLFeatureNotSupportedException - if the JDBC driver does not support this method

从以下版本开始:

1.4

setString

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. The string will overwrite the existing characters in the Clob object starting at the position pos. If the end of the Clob value is reached while writing the given string, then the length of the Clob value will be increased to accommodate the extra characters.

Note: If the value specified for pos is greater then the length+1 of the CLOB value then the behavior is undefined. Some JDBC drivers may throw a SQLException while other drivers may support this operation.

参数:

pos - the position at which to start writing to this CLOB object; The first position is 1

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

返回:

the number of characters written

抛出:

SQLException - if there is an error accessing the CLOB value or if pos is less than 1

SQLFeatureNotSupportedException - if the JDBC driver does not support this method

从以下版本开始:

1.4

setAsciiStream

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. Characters written to the stream will overwrite the existing characters in the Clob object starting at the position pos. If the end of the Clob value is reached while writing characters to the stream, then the length of the Clob value will be increased to accommodate the extra characters.

Note: If the value specified for pos is greater then the length+1 of the CLOB value then the behavior is undefined. Some JDBC drivers may throw a SQLException while other drivers may support this operation.

参数:

pos - the position at which to start writing to this CLOB object; The first position is 1

返回:

the stream to which ASCII encoded characters can be written

抛出:

SQLException - if there is an error accessing the CLOB value or if pos is less than 1

SQLFeatureNotSupportedException - if the JDBC driver does not support this method

从以下版本开始:

1.4

另请参阅:

getAsciiStream()

setCharacterStream

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. Characters written to the stream will overwrite the existing characters in the Clob object starting at the position pos. If the end of the Clob value is reached while writing characters to the stream, then the length of the Clob value will be increased to accommodate the extra characters.

Note: If the value specified for pos is greater then the length+1 of the CLOB value then the behavior is undefined. Some JDBC drivers may throw a SQLException while other drivers may support this operation.

参数:

pos - the position at which to start writing to the CLOB value; The first position is 1

返回:

a stream to which Unicode encoded characters can be written

抛出:

SQLException - if there is an error accessing the CLOB value or if pos is less than 1

SQLFeatureNotSupportedException - if the JDBC driver does not support this method

从以下版本开始:

1.4

另请参阅:

getCharacterStream()

truncate

void truncate(long len)
       throws SQLException

Truncates the CLOB value that this Clob designates to have a length of len characters.

Note: If the value specified for pos is greater then the length+1 of the CLOB value then the behavior is undefined. Some JDBC drivers may throw a SQLException while other drivers may support this operation.

参数:

len - the length, in characters, to which the CLOB value should be truncated

抛出:

SQLException - if there is an error accessing the CLOB value or if len is less than 0

SQLFeatureNotSupportedException - if the JDBC driver does not support this method

从以下版本开始:

1.4

free

void free()
   throws SQLException

This method frees the Clob object and releases the resources the resources that it holds. The object is invalid once the free method is called.

After free has been called, any attempt to invoke a method other than free will result in a SQLException being thrown. If free is called multiple times, the subsequent calls to free are treated as a no-op.

抛出:

SQLException - if an error occurs releasing the Clob's resources

SQLFeatureNotSupportedException - if the JDBC driver does not support this method

从以下版本开始:

1.6

getCharacterStream

Reader getCharacterStream(long pos,
                          long length)
                   throws SQLException

Returns a Reader object that contains a partial Clob value, starting with the character specified by pos, which is length characters in length.

参数:

pos - the offset to the first character of the partial value to be retrieved. The first character in the Clob is at position 1.

length - the length in characters of the partial value to be retrieved.

返回:

Reader through which the partial Clob value can be read.

抛出:

SQLException - if pos is less than 1 or if pos is greater than the number of characters in the Clob or if pos + length is greater than the number of characters in the Clob

SQLFeatureNotSupportedException - if the JDBC driver does not support this method

从以下版本开始:

1.6