jdbcclob.java

纯Java的数据库

        if (searchstr == null || start > Integer.MAX_VALUE) {
            return -1;
        }

        final String ldata = data;
        final int    pos   = ldata.indexOf(searchstr, (int) --start);

        return (pos < 0) ? -1
                         : pos + 1;
    }

    /**
     * Retrieves the character position at which the specified
     * <code>Clob</code> object <code>searchstr</code> appears in this
     * <code>Clob</code> object.  The search begins at position
     * <code>start</code>.
     *
     * @param searchstr the <code>Clob</code> object for which to search
     * @param start the position at which to begin searching; the first
     *              position is 1
     * @return the position at which the <code>Clob</code> object appears
     *              or -1 if it is not present; the first position is 1
     * @exception SQLException if there is an error accessing the
     *            <code>CLOB</code> value
     *
     * @since JDK 1.2, HSQLDB 1.7.2
     */
    public long position(final Clob searchstr,
                         long start) throws SQLException {

        if (searchstr == null) {
            return -1;
        }

        final String ldata = data;
        final long   dlen  = ldata.length();
        final long   sslen = searchstr.length();

        start--;    //***** FOIRGOT THIS *******

// This is potentially much less expensive than materializing a large
// substring from some other vendor's CLOB.  Indeed, we should probably
// do the comparison piecewise, using an in-memory buffer (or temp-files
// when available), if it is detected that the input CLOB is very long.
        if (start > dlen - sslen) {
            return -1;
        }

        // by now, we know sslen and start are both < Integer.MAX_VALUE
        String s;

        if (searchstr instanceof jdbcClob) {
            s = ((jdbcClob) searchstr).data;
        } else {
            s = searchstr.getSubString(1L, (int) sslen);
        }

        final int pos = ldata.indexOf(s, (int) start);

        return (pos < 0) ? -1
                         : pos + 1;
    }

    //---------------------------- jdbc 3.0 -----------------------------------

    /**
     * Writes the given Java <code>String</code> to the <code>CLOB</code>
     * value that this <code>Clob</code> object designates at the position
     * <code>pos</code>. <p>
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information:</h3> <p>
     *
     * HSLQDB 1.7.2 does not support this feature. <p>
     *
     * Calling this method always throws an <code>SQLException</code>.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param pos the position at which to start writing to the
     *          <code>CLOB</code> value that this <code>Clob</code> object
     *          represents
     * @param str the string to be written to the <code>CLOB</code>
     *          value that this <code>Clob</code> designates
     * @return the number of characters written
     * @exception SQLException if there is an error accessing the
     *            <code>CLOB</code> value
     *
     * @since JDK 1.4, HSQLDB 1.7.2
     */
    public int setString(long pos, String str) throws SQLException {
        throw Util.notSupported();
    }

    /**
     * Writes <code>len</code> characters of <code>str</code>, starting
     * at character <code>offset</code>, to the <code>CLOB</code> value
     * that this <code>Clob</code> represents. <p>
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information:</h3> <p>
     *
     * HSLQDB 1.7.2 does not support this feature. <p>
     *
     * Calling this method always throws an <code>SQLException</code>.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param pos the position at which to start writing to this
     *          <code>CLOB</code> object
     * @param str the string to be written to the <code>CLOB</code>
     *          value that this <code>Clob</code> object represents
     * @param offset the offset into <code>str</code> to start reading
     *          the characters to be written
     * @param len the number of characters to be written
     * @return the number of characters written
     * @exception SQLException if there is an error accessing the
     *          <code>CLOB</code> value
     *
     * @since JDK 1.4, HSQLDB 1.7.2
     */
    public int setString(long pos, String str, int offset,
                         int len) throws SQLException {
        throw Util.notSupported();
    }

    /**
     * Retrieves a stream to be used to write Ascii characters to the
     * <code>CLOB</code> value that this <code>Clob</code> object represents,
     * starting at position <code>pos</code>. <p>
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information:</h3> <p>
     *
     * HSLQDB 1.7.2 does not support this feature. <p>
     *
     * Calling this method always throws an <code>SQLException</code>.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param pos the position at which to start writing to this
     *        <code>CLOB</code> object
     * @return the stream to which ASCII encoded characters can be written
     * @exception SQLException if there is an error accessing the
     *            <code>CLOB</code> value
     * @see #getAsciiStream
     *
     * @since JDK 1.4, HSQLDB 1.7.2
     */
    public java.io.OutputStream setAsciiStream(long pos) throws SQLException {
        throw Util.notSupported();
    }

    /**
     * Retrieves a stream to be used to write a stream of Unicode characters
     * to the <code>CLOB</code> value that this <code>Clob</code> object
     * represents, at position <code>pos</code>. <p>
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information:</h3> <p>
     *
     * HSLQDB 1.7.2 does not support this feature. <p>
     *
     * Calling this method always throws an <code>SQLException</code>.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param  pos the position at which to start writing to the
     *        <code>CLOB</code> value
     *
     * @return a stream to which Unicode encoded characters can be written
     * @exception SQLException if there is an error accessing the
     *            <code>CLOB</code> value
     * @see #getCharacterStream
     *
     * @since JDK 1.4, HSQLDB 1.7.2
     */
    public java.io.Writer setCharacterStream(long pos) throws SQLException {
        throw Util.notSupported();
    }

    /**
     * Truncates the <code>CLOB</code> value that this <code>Clob</code>
     * designates to have a length of <code>len</code>
     * characters. <p>
     *
     * <!-- start release-specific documentation -->
     * <div class="ReleaseSpecificDocumentation">
     * <h3>HSQLDB-Specific Information:</h3> <p>
     *
     * This operation affects only the client-side value; it has no effect upon
     * the value as it is stored in the database.
     * </div>
     * <!-- end release-specific documentation -->
     *
     * @param len the length, in bytes, to which the <code>CLOB</code> value
     *        should be truncated
     * @exception SQLException if there is an error accessing the
     *            <code>CLOB</code> value
     *
     * @since JDK 1.4, HSQLDB 1.7.2
     */
    public void truncate(final long len) throws SQLException {

        final String ldata = data;
        final long   dlen  = ldata.length();
        final long   chars = len >> 1;

        if (chars == dlen) {

            // nothing has changed, so there's nothing to be done
        } else if (len < 0 || chars > dlen) {
            throw Util.sqlException(Trace.INVALID_JDBC_ARGUMENT,
                                    Long.toString(len));
        } else {

            // use new String() to ensure we get rid of slack
            data = new String(ldata.substring(0, (int) chars));
        }
    }

//#ifdef JAVA6
/*
    public void free() throws SQLException
    {
        throw new UnsupportedOperationException("Not supported yet.");
    }

    public Reader getCharacterStream(long pos, long length) throws SQLException
    {
        throw new UnsupportedOperationException("Not supported yet.");
    }
*/
//#endif JAVA6
}