1. 首页
  2. JavaAPI

Java compact2, compact3 java.sql Interface Clob（JDK8）

149 阅读 0 评论

Skip navigation links
Java™ Platform
Standard Ed. 8
  • Summary: 
  • Nested | 
  • Field | 
  • Constr | 
  • Method
  • Detail: 
  • Field | 
  • Constr | 
  • Method
compact2, compact3
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

      All Methods Instance Methods Abstract Methods 
      Modifier and Type Method and Description
      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(Clob searchstr, long start)
      Retrieves the character position at which the specified Clob object searchstr appears in 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.
      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 Detail

      • 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)

      • 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 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.

        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 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.

        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 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.

        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 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.

        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 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.

        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 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.

        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
Skip navigation links
Java™ Platform
Standard Ed. 8
  • Summary: 
  • Nested | 
  • Field | 
  • Constr | 
  • Method
  • Detail: 
  • Field | 
  • Constr | 
  • Method

Submit a bug or feature
For further API reference and developer documentation, see Java SE Documentation. That documentation contains more detailed, developer-targeted descriptions, with conceptual overviews, definitions of terms, workarounds, and working code examples.
Copyright © 1993, 2022, Oracle and/or its affiliates. All rights reserved. Use is subject to license terms. Also see the documentation redistribution policy.

微信小程序

微信扫一扫体验

微信公众账号

微信扫一扫加关注

 发表
评论 返回
顶部