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Tomcat example source code file (GzipOutputFilter.java)

This example Tomcat source code file (GzipOutputFilter.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Tomcat tags/keywords

bytechunk, bytechunk, encoding, fakeoutputstream, gzipoutputfilter, gzipoutputstream, gzipoutputstream, io, ioexception, ioexception, outputfilter, outputstream, outputstream, response, string, zip

The Tomcat GzipOutputFilter.java source code

/*
 *  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.coyote.http11.filters;

import java.io.IOException;
import java.io.OutputStream;
import java.util.zip.GZIPOutputStream;

import org.apache.tomcat.util.buf.ByteChunk;

import org.apache.coyote.OutputBuffer;
import org.apache.coyote.Response;
import org.apache.coyote.http11.OutputFilter;

/**
 * Gzip output filter.
 * 
 * @author Remy Maucherat
 */
public class GzipOutputFilter implements OutputFilter {


    // -------------------------------------------------------------- Constants


    protected static final String ENCODING_NAME = "gzip";
    protected static final ByteChunk ENCODING = new ByteChunk();


    // ----------------------------------------------------- Static Initializer


    static {
        ENCODING.setBytes(ENCODING_NAME.getBytes(), 0, ENCODING_NAME.length());
    }


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


    /**
     * Next buffer in the pipeline.
     */
    protected OutputBuffer buffer;


    /**
     * Compression output stream.
     */
    protected GZIPOutputStream compressionStream = null;


    /**
     * Fake internal output stream.
     */
    protected OutputStream fakeOutputStream = new FakeOutputStream();


    // --------------------------------------------------- OutputBuffer Methods


    /**
     * Write some bytes.
     * 
     * @return number of bytes written by the filter
     */
    public int doWrite(ByteChunk chunk, Response res)
        throws IOException {
        if (compressionStream == null) {
            compressionStream = new GZIPOutputStream(fakeOutputStream);
        }
        compressionStream.write(chunk.getBytes(), chunk.getStart(), 
                                chunk.getLength());
        return chunk.getLength();
    }


    // --------------------------------------------------- OutputFilter Methods


    /**
     * Some filters need additional parameters from the response. All the 
     * necessary reading can occur in that method, as this method is called
     * after the response header processing is complete.
     */
    public void setResponse(Response response) {
    }


    /**
     * Set the next buffer in the filter pipeline.
     */
    public void setBuffer(OutputBuffer buffer) {
        this.buffer = buffer;
    }


    /**
     * End the current request. It is acceptable to write extra bytes using
     * buffer.doWrite during the execution of this method.
     */
    public long end()
        throws IOException {
        if (compressionStream == null) {
            compressionStream = new GZIPOutputStream(fakeOutputStream);
        }
        compressionStream.finish();
        compressionStream.close();
        return ((OutputFilter) buffer).end();
    }


    /**
     * Make the filter ready to process the next request.
     */
    public void recycle() {
        // Set compression stream to null
        compressionStream = null;
    }


    /**
     * Return the name of the associated encoding; Here, the value is 
     * "identity".
     */
    public ByteChunk getEncodingName() {
        return ENCODING;
    }


    // ------------------------------------------- FakeOutputStream Inner Class


    protected class FakeOutputStream
        extends OutputStream {
        protected ByteChunk outputChunk = new ByteChunk();
        protected byte[] singleByteBuffer = new byte[1];
        public void write(int b)
            throws IOException {
            // Shouldn't get used for good performance, but is needed for 
            // compatibility with Sun JDK 1.4.0
            singleByteBuffer[0] = (byte) (b & 0xff);
            outputChunk.setBytes(singleByteBuffer, 0, 1);
            buffer.doWrite(outputChunk, null);
        }
        public void write(byte[] b, int off, int len)
            throws IOException {
            outputChunk.setBytes(b, off, len);
            buffer.doWrite(outputChunk, null);
        }
        public void flush() throws IOException {}
        public void close() throws IOException {}
    }


}

Other Tomcat examples (source code examples)

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