TcpBufferedOutputStream.java

/**
 *
 * 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.codehaus.stomp.tcp;

import java.io.EOFException;
import java.io.FilterOutputStream;
import java.io.IOException;
import java.io.OutputStream;

/**
   * An optimized buffered outputstream for Tcp
      *
   * @version $Revision: 50 $
 */
public class TcpBufferedOutputStream extends FilterOutputStream {
    private static final int BUFFER_SIZE = 8192;
    private byte[] buffer;
    private int bufferlen;
    private int count;
    private boolean closed;

    /**
     * Constructor
          *
     * @param out
     */
    public TcpBufferedOutputStream(OutputStream out) {
        this(out, TcpBufferedOutputStream.BUFFER_SIZE);
    }

    /**
     * Creates a new buffered output stream to write data to the specified underlying output stream with the specified buffer
     * size.
          *
     * @param out the underlying output stream.
     * @param size the buffer size.
     * @throws IllegalArgumentException if size <= 0.
     */
    public TcpBufferedOutputStream(OutputStream out, int size) {
        super(out);
        if (size <= 0) {
            throw new IllegalArgumentException("Buffer size <= 0");
        }
        buffer = new byte[size];
        bufferlen = size;
    }

    /**
     * write a byte on to the stream
          *
     * @param b - byte to write
     * @throws IOException
     */
    public void write(int b) throws IOException {
        if ((bufferlen - count) < 1) {
            flush();
        }
        buffer[count++] = (byte) b;
    }

    /**
     * write a byte array to the stream
          *
     * @param b the byte buffer
     * @param off the offset into the buffer
     * @param len the length of data to write
     * @throws IOException
     */
    public void write(byte[] b, int off, int len) throws IOException {
        if ((bufferlen - count) < len) {
            flush();
        }
        if (buffer.length >= len) {
            System.arraycopy(b, off, buffer, count, len);
            count += len;
        } else {
            out.write(b, off, len);
        }
    }

    /**
     * flush the data to the output stream This doesn't call flush on the underlying outputstream, because Tcp is particularly
     * efficent at doing this itself ....
          *
     * @throws IOException
     */
    public void flush() throws IOException {
        if (count > 0 && out != null) {
            out.write(buffer, 0, count);
            count = 0;
        }
    }

    /**
     * close this stream
          *
     * @throws IOException
     */
    public void close() throws IOException {
        super.close();
        closed = true;
    }

    /**
     * Checks that the stream has not been closed
          *
     * @throws IOException
     */
    private void checkClosed() throws IOException {
        if (closed) {
            throw new EOFException("Cannot write to the stream any more it has already been closed");
        }
    }
}