compressionresponsestream.java

struts_spring_hibernate开发实例

/*
 * CompressionResponseStream.java
 * $Header: /home/cvs/jakarta-tomcat-4.0/webapps/examples/WEB-INF/classes/compressionFilters/CompressionResponseStream.java,v 1.7 2003/09/13 14:28:46 funkman Exp $
 * $Revision: 1.7 $
 * $Date: 2003/09/13 14:28:46 $
 *
 * ====================================================================
 *
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 * [Additional notices, if required by prior licensing conditions]
 *
 */
package jaoso.framework.web.filter.compression;

import java.io.IOException;

import java.util.zip.GZIPOutputStream;

import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;

/**
 * Implementation of <b>ServletOutputStream </b> that works with the
 * CompressionServletResponseWrapper implementation.
 * 
 * @author Amy Roh
 * @author Dmitri Valdin
 * @version $Revision: 1.7 $, $Date: 2003/09/13 14:28:46 $
 */
public class CompressionResponseStream extends ServletOutputStream {
	/**
	 * The underlying gzip output stream to which we should write data.
	 */
	protected GZIPOutputStream gzipstream = null;

	/**
	 * The response with which this servlet output stream is associated.
	 */
	protected HttpServletResponse response = null;

	/**
	 * The underlying servket output stream to which we should write data.
	 */
	protected ServletOutputStream output = null;

	/**
	 * The buffer through which all of our output bytes are passed.
	 */
	protected byte[] buffer = null;

	/**
	 * Has this stream been closed?
	 */
	protected boolean closed = false;

	/**
	 * The number of data bytes currently in the buffer.
	 */
	protected int bufferCount = 0;

	// ----------------------------------------------------- Instance Variables

	/**
	 * The threshold number which decides to compress or not. Users can
	 * configure in web.xml to set it to fit their needs.
	 */
	protected int compressionThreshold = 0;

	/**
	 * The content length past which we will not write, or -1 if there is no
	 * defined content length.
	 */
	protected int length = -1;

	/**
	 * Debug level
	 */
	private int debug = 0;

	// ----------------------------------------------------------- Constructors

	/**
	 * Construct a servlet output stream associated with the specified Response.
	 * 
	 * @param response
	 *            The associated response
	 */
	public CompressionResponseStream(HttpServletResponse response)
			throws IOException {
		super();
		closed = false;
		this.response = response;
		this.output = response.getOutputStream();
	}

	// --------------------------------------------------------- Public Methods

	/**
	 * Set debug level
	 */
	public void setDebugLevel(int debug) {
		this.debug = debug;
	}

	/**
	 * Close this output stream, causing any buffered data to be flushed and any
	 * further output data to throw an IOException.
	 */
	public void close() throws IOException {
		if (debug > 1) {
			System.out.println("close() @ CompressionResponseStream");
		}

		if (closed) {
			throw new IOException("This output stream has already been closed");
		}

		if (gzipstream != null) {
			flushToGZip();
			gzipstream.close();
			gzipstream = null;
		} else {
			if (bufferCount > 0) {
				if (debug > 2) {
					System.out.print("output.write(");
					System.out.write(buffer, 0, bufferCount);
					System.out.println(")");
				}

				output.write(buffer, 0, bufferCount);
				bufferCount = 0;
			}
		}

		output.close();
		closed = true;
	}

	// -------------------------------------------------------- Package Methods

	/**
	 * Has this response stream been closed?
	 */
	public boolean closed() {
		return (this.closed);
	}

	/**
	 * Flush any buffered data for this output stream, which also causes the
	 * response to be committed.
	 */
	public void flush() throws IOException {
		if (debug > 1) {
			System.out.println("flush() @ CompressionResponseStream");
		}

		if (closed) {
			throw new IOException("Cannot flush a closed output stream");
		}

		if (gzipstream != null) {
			gzipstream.flush();
		}
	}

	/**
	 * DOCUMENT ME!
	 * 
	 * @throws IOException
	 *             DOCUMENT ME!
	 */
	public void flushToGZip() throws IOException {
		if (debug > 1) {
			System.out.println("flushToGZip() @ CompressionResponseStream");
		}

		if (bufferCount > 0) {
			if (debug > 1) {
				System.out.println("flushing out to GZipStream, bufferCount = "
						+ bufferCount);
			}

			writeToGZip(buffer, 0, bufferCount);
			bufferCount = 0;
		}
	}

	/**
	 * Write the specified byte to our output stream.
	 * 
	 * @param b
	 *            The byte to be written
	 * 
	 * @exception IOException
	 *                if an input/output error occurs
	 */
	public void write(int b) throws IOException {
		if (debug > 1) {
			System.out.println("write " + b + " in CompressionResponseStream ");
		}

		if (closed) {
			throw new IOException("Cannot write to a closed output stream");
		}

		if (bufferCount >= buffer.length) {
			flushToGZip();
		}

		buffer[bufferCount++] = (byte) b;
	}

	/**
	 * Write <code>b.length</code> bytes from the specified byte array to our
	 * output stream.
	 * 
	 * @param b
	 *            The byte array to be written
	 * 
	 * @exception IOException
	 *                if an input/output error occurs
	 */
	public void write(byte[] b) throws IOException {
		write(b, 0, b.length);
	}

	/**
	 * Write <code>len</code> bytes from the specified byte array, starting at
	 * the specified offset, to our output stream.
	 * 
	 * @param b
	 *            The byte array containing the bytes to be written
	 * @param off
	 *            Zero-relative starting offset of the bytes to be written
	 * @param len
	 *            The number of bytes to be written
	 * 
	 * @exception IOException
	 *                if an input/output error occurs
	 */
	public void write(byte[] b, int off, int len) throws IOException {
		if (debug > 1) {
			System.out.println("write, bufferCount = " + bufferCount
					+ " len = " + len + " off = " + off);
		}

		if (debug > 2) {
			System.out.print("write(");
			System.out.write(b, off, len);
			System.out.println(")");
		}

		if (closed) {
			throw new IOException("Cannot write to a closed output stream");
		}

		if (len == 0) {
			return;
		}

		// Can we write into buffer ?
		if (len <= (buffer.length - bufferCount)) {
			System.arraycopy(b, off, buffer, bufferCount, len);
			bufferCount += len;

			return;
		}

		// There is not enough space in buffer. Flush it ...
		flushToGZip();

		// ... and try again. Note, that bufferCount = 0 here !
		if (len <= (buffer.length - bufferCount)) {
			System.arraycopy(b, off, buffer, bufferCount, len);
			bufferCount += len;

			return;
		}

		// write direct to gzip
		writeToGZip(b, off, len);
	}

	/**
	 * DOCUMENT ME!
	 * 
	 * @param b
	 *            DOCUMENT ME!
	 * @param off
	 *            DOCUMENT ME!
	 * @param len
	 *            DOCUMENT ME!
	 * 
	 * @throws IOException
	 *             DOCUMENT ME!
	 */
	public void writeToGZip(byte[] b, int off, int len) throws IOException {
		if (debug > 1) {
			System.out.println("writeToGZip, len = " + len);
		}

		if (debug > 2) {
			System.out.print("writeToGZip(");
			System.out.write(b, off, len);
			System.out.println(")");
		}

		if (gzipstream == null) {
			if (debug > 1) {
				System.out.println("new GZIPOutputStream");
			}

			response.addHeader("Content-Encoding", "gzip");
			gzipstream = new GZIPOutputStream(output);
		}

		gzipstream.write(b, off, len);
	}

	/**
	 * Set the compressionThreshold number and create buffer for this size
	 */
	protected void setBuffer(int threshold) {
		compressionThreshold = threshold;
		buffer = new byte[compressionThreshold];

		if (debug > 1) {
			System.out.println("buffer is set to " + compressionThreshold);
		}
	}
}