Module java.sql
Package java.sql

Interface Clob

All Known Subinterfaces:
NClob
All Known Implementing Classes:
SerialClob
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.

Since:
1.2

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    free()
    This method releases the resources that the Clob object 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.

  • Method Details

    • length

      long length() throws SQLException
      Retrieves the number of characters in the CLOB value designated by this Clob object.
      Returns:
      length of the CLOB in characters
      Throws:
      SQLException - if there is an error accessing the length of the CLOB value
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      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.
      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; the value for length must be 0 or greater
      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; if pos is less than 1 or length is less than 0
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      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).
      Returns:
      a java.io.Reader object containing the CLOB data
      Throws:
      SQLException - if there is an error accessing the CLOB value
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      1.2
      See Also:
      setCharacterStream(long)

    • getAsciiStream

      InputStream getAsciiStream() throws SQLException
      Retrieves the CLOB value designated by this Clob object as an ascii stream.
      Returns:
      a java.io.InputStream object containing the CLOB data
      Throws:
      SQLException - if there is an error accessing the CLOB value
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      1.2
      See Also:
      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.
      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 or if pos is less than 1
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      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.
      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 or if start is less than 1
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      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 than the length+1 of the CLOB value then the behavior is undefined. Some JDBC drivers may throw an SQLException while other drivers may support this operation.

      Parameters:
      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
      Returns:
      the number of characters written
      Throws:
      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
      Since:
      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 than the length+1 of the CLOB value then the behavior is undefined. Some JDBC drivers may throw an SQLException while other drivers may support this operation.

      Parameters:
      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
      Returns:
      the number of characters written
      Throws:
      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
      Since:
      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 than the length+1 of the CLOB value then the behavior is undefined. Some JDBC drivers may throw an SQLException while other drivers may support this operation.

      Parameters:
      pos - the position at which to start writing to this CLOB object; The first position is 1
      Returns:
      the stream to which ASCII encoded characters can be written
      Throws:
      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
      Since:
      1.4
      See Also:
      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 than the length+1 of the CLOB value then the behavior is undefined. Some JDBC drivers may throw an SQLException while other drivers may support this operation.

      Parameters:
      pos - the position at which to start writing to the CLOB value; The first position is 1
      Returns:
      a stream to which Unicode encoded characters can be written
      Throws:
      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
      Since:
      1.4
      See Also:
      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 than the length+1 of the CLOB value then the behavior is undefined. Some JDBC drivers may throw an SQLException while other drivers may support this operation.

      Parameters:
      len - the length, in characters, to which the CLOB value should be truncated
      Throws:
      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
      Since:
      1.4

    • free

      void free() throws SQLException
      This method releases the resources that the Clob object 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.

      Throws:
      SQLException - if an error occurs releasing the Clob's resources
      SQLFeatureNotSupportedException - if the JDBC driver does not support this method
      Since:
      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.
      Parameters:
      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.
      Returns:
      Reader through which the partial Clob value can be read.
      Throws:
      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
      Since:
      1.6