java/engine/org/apache/derby/impl/jdbc/ClobAsciiStream.java

/* 

   Derby - Class org.apache.derby.impl.jdbc.ClobAsciiStream

   Licensed to the Apache Software Foundation (ASF) under one
   or more contributor license agreements.  See the NOTICE file
   distributed with this work for additional information
   regarding copyright ownership.  The ASF licenses this file
   to you under the Apache License, Version 2.0 (the
   "License"); you may not use this file except in compliance
   with the License.  You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing,
   software distributed under the License is distributed on an
   "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
   KIND, either express or implied.  See the License for the
   specific language governing permissions and limitations
   under the License.

 */
package org.apache.derby.impl.jdbc;

import java.io.IOException;
import java.io.OutputStream;
import java.io.Writer;

/**
 * Wrap a Writer as an OutputStream to support Clob.setAsciiStream().
 * Any value written to the OutputStream is a valid ASCII value
 * (0-255 from JDBC 4 spec appendix C2) thus this class simply
 * passes the written values onto the Writer.
 *
 */
final class ClobAsciiStream extends OutputStream {

    private final Writer writer;
    private final char[] buffer = new char[1024];
    
    ClobAsciiStream (Writer writer){
        this.writer = writer;
    }

    /**
     * Writes the specified byte to this output stream.
     * <p>
     * The general contract for <code>write</code> is that one byte is written
     * to the output stream. The byte to be written is the eight low-order bits
     * of the argument <code>b</code>. The 24 high-order bits of <code>b</code>
     * are ignored.
     * 
     * @param b   the <code>byte</code>.
     * @exception IOException  if an I/O error occurs. In particular, 
     *             an <code>IOException</code> may be thrown if the 
     *             output stream has been closed.
     */
    public void write(int b) throws IOException {
        writer.write(b & 0xff);
    }

    /**
     * Writes <code>len</code> bytes from the specified byte array 
     * starting at offset <code>off</code> to this output stream. 
     * <p>
     * The general contract for <code>write(b, off, len)</code> is that 
     * some of the bytes in the array <code>b</code> are written to the 
     * output stream in order; element <code>b[off]</code> is the first 
     * byte written and <code>b[off+len-1]</code> is the last byte written 
     * by this operation.
     * <p>
     * The <code>write</code> method of <code>OutputStream</code> calls 
     * the write method of one argument on each of the bytes to be 
     * written out. Subclasses are encouraged to override this method and 
     * provide a more efficient implementation. 
     * <p>
     * If <code>b</code> is <code>null</code>, a 
     * <code>NullPointerException</code> is thrown.
     * <p>
     * If <code>off</code> is negative, or <code>len</code> is negative, or 
     * <code>off+len</code> is greater than the length of the array 
     * <code>b</code>, then an <tt>IndexOutOfBoundsException</tt> is thrown.
     * 
     * @param b     the data.
     * @param off   the start offset in the data.
     * @param len   the number of bytes to write.
     * @exception IOException  if an I/O error occurs. In particular, 
     *             an <code>IOException</code> is thrown if the output 
     *             stream is closed.
     */
    public void write(byte[] b, int off, int len) throws IOException {
        
        while (len > 0)
        {
            int clen = Math.min(len, buffer.length);
            for (int i = 0; i < clen; i++) {
                buffer[i] = (char)(b[off + i] & 0xff);
            }
            writer.write(buffer, 0, clen);
            off += clen;
            len -= clen;
        }
    }    
}