/*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package compressionFilters;
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import java.io.IOException;
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import java.io.OutputStream;
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import java.util.Arrays;
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import java.util.zip.GZIPOutputStream;
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import javax.servlet.ServletOutputStream;
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import javax.servlet.WriteListener;
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/**
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* Implementation of <b>ServletOutputStream</b> that works with
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* the CompressionServletResponseWrapper implementation.
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*
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* @author Amy Roh
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* @author Dmitri Valdin
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*/
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public class CompressionResponseStream extends ServletOutputStream {
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// ----------------------------------------------------------- Constructors
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/**
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* Construct a servlet output stream associated with the specified Response.
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*
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* @param responseWrapper The associated response wrapper
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* @param originalOutput the output stream
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*/
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public CompressionResponseStream(
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CompressionServletResponseWrapper responseWrapper,
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ServletOutputStream originalOutput) {
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super();
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closed = false;
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this.response = responseWrapper;
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this.output = originalOutput;
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}
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// ----------------------------------------------------- Instance Variables
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/**
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* The threshold number which decides to compress or not.
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* Users can configure in web.xml to set it to fit their needs.
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*/
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protected int compressionThreshold = 0;
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/**
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* The compression buffer size to avoid chunking
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*/
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protected int compressionBuffer = 0;
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/**
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* The mime types to compress
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*/
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protected String[] compressionMimeTypes = {"text/html", "text/xml", "text/plain"};
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/**
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* Debug level
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*/
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private int debug = 0;
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/**
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* The buffer through which all of our output bytes are passed.
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*/
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protected byte[] buffer = null;
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/**
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* The number of data bytes currently in the buffer.
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*/
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protected int bufferCount = 0;
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/**
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* The underlying gzip output stream to which we should write data.
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*/
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protected OutputStream gzipstream = null;
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/**
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* Has this stream been closed?
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*/
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protected boolean closed = false;
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/**
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* The response with which this servlet output stream is associated.
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*/
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protected final CompressionServletResponseWrapper response;
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/**
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* The underlying servlet output stream to which we should write data.
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*/
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protected final ServletOutputStream output;
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// --------------------------------------------------------- Public Methods
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/**
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* Set debug level.
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*
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* @param debug The higher the number, the more detail shown. Currently the
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* range 0 (none) to 3 (everything) is used.
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*/
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public void setDebugLevel(int debug) {
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this.debug = debug;
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}
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/**
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* Set the compressionThreshold number and create buffer for this size
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*/
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protected void setCompressionThreshold(int compressionThreshold) {
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this.compressionThreshold = compressionThreshold;
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buffer = new byte[this.compressionThreshold];
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if (debug > 1) {
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System.out.println("compressionThreshold is set to "+ this.compressionThreshold);
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}
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}
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/**
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* The compression buffer size to avoid chunking
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*/
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protected void setCompressionBuffer(int compressionBuffer) {
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this.compressionBuffer = compressionBuffer;
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if (debug > 1) {
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System.out.println("compressionBuffer is set to "+ this.compressionBuffer);
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}
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}
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/**
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* Set supported mime types.
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*
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* @param compressionMimeTypes The mimetypes that will be compressed.
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*/
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public void setCompressionMimeTypes(String[] compressionMimeTypes) {
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this.compressionMimeTypes = compressionMimeTypes;
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if (debug > 1) {
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System.out.println("compressionMimeTypes is set to " +
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Arrays.toString(this.compressionMimeTypes));
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}
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}
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/**
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* Close this output stream, causing any buffered data to be flushed and
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* any further output data to throw an IOException.
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*/
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@Override
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public void close() throws IOException {
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if (debug > 1) {
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System.out.println("close() @ CompressionResponseStream");
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}
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if (closed) {
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throw new IOException("This output stream has already been closed");
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}
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if (gzipstream != null) {
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flushToGZip();
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gzipstream.close();
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gzipstream = null;
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} else {
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if (bufferCount > 0) {
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if (debug > 2) {
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System.out.print("output.write(");
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System.out.write(buffer, 0, bufferCount);
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System.out.println(")");
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}
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output.write(buffer, 0, bufferCount);
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bufferCount = 0;
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}
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}
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output.close();
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closed = true;
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}
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/**
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* Flush any buffered data for this output stream, which also causes the
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* response to be committed.
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*/
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@Override
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public void flush() throws IOException {
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if (debug > 1) {
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System.out.println("flush() @ CompressionResponseStream");
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}
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if (closed) {
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throw new IOException("Cannot flush a closed output stream");
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}
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if (gzipstream != null) {
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gzipstream.flush();
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}
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}
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public void flushToGZip() throws IOException {
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if (debug > 1) {
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System.out.println("flushToGZip() @ CompressionResponseStream");
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}
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if (bufferCount > 0) {
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if (debug > 1) {
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System.out.println("flushing out to GZipStream, bufferCount = " + bufferCount);
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}
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writeToGZip(buffer, 0, bufferCount);
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bufferCount = 0;
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}
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}
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/**
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* Write the specified byte to our output stream.
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*
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* @param b The byte to be written
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*
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* @exception IOException if an input/output error occurs
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*/
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@Override
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public void write(int b) throws IOException {
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if (debug > 1) {
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System.out.println("write "+b+" in CompressionResponseStream ");
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}
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if (closed) {
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throw new IOException("Cannot write to a closed output stream");
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}
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if (bufferCount >= buffer.length) {
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flushToGZip();
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}
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buffer[bufferCount++] = (byte) b;
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}
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/**
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* Write <code>b.length</code> bytes from the specified byte array
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* to our output stream.
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*
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* @param b The byte array to be written
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*
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* @exception IOException if an input/output error occurs
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*/
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@Override
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public void write(byte b[]) throws IOException {
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write(b, 0, b.length);
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}
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/**
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* TODO SERVLET 3.1
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*/
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@Override
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public boolean isReady() {
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// TODO Auto-generated method stub
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return false;
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}
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/**
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* TODO SERVLET 3.1
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*/
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@Override
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public void setWriteListener(WriteListener listener) {
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// TODO Auto-generated method stub
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}
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/**
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* Write <code>len</code> bytes from the specified byte array, starting
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* at the specified offset, to our output stream.
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*
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* @param b The byte array containing the bytes to be written
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* @param off Zero-relative starting offset of the bytes to be written
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* @param len The number of bytes to be written
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*
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* @exception IOException if an input/output error occurs
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*/
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@Override
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public void write(byte b[], int off, int len) throws IOException {
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if (debug > 1) {
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System.out.println("write, bufferCount = " + bufferCount + " len = " + len + " off = " + off);
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}
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if (debug > 2) {
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System.out.print("write(");
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System.out.write(b, off, len);
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System.out.println(")");
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}
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if (closed) {
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throw new IOException("Cannot write to a closed output stream");
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}
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if (len == 0) {
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return;
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}
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// Can we write into buffer ?
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if (len <= (buffer.length - bufferCount)) {
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System.arraycopy(b, off, buffer, bufferCount, len);
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bufferCount += len;
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return;
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}
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// There is not enough space in buffer. Flush it ...
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flushToGZip();
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// ... and try again. Note, that bufferCount = 0 here !
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if (len <= (buffer.length - bufferCount)) {
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System.arraycopy(b, off, buffer, bufferCount, len);
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bufferCount += len;
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return;
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}
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// write direct to gzip
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writeToGZip(b, off, len);
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}
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public void writeToGZip(byte b[], int off, int len) throws IOException {
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if (debug > 1) {
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System.out.println("writeToGZip, len = " + len);
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}
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if (debug > 2) {
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System.out.print("writeToGZip(");
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System.out.write(b, off, len);
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System.out.println(")");
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}
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if (gzipstream == null) {
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if (debug > 1) {
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System.out.println("new GZIPOutputStream");
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}
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boolean alreadyCompressed = false;
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String contentEncoding = response.getHeader("Content-Encoding");
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if (contentEncoding != null) {
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if (contentEncoding.contains("gzip")) {
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alreadyCompressed = true;
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if (debug > 0) {
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System.out.println("content is already compressed");
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}
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} else {
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if (debug > 0) {
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System.out.println("content is not compressed yet");
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}
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}
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}
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boolean compressibleMimeType = false;
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// Check for compatible MIME-TYPE
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if (compressionMimeTypes != null) {
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if (startsWithStringArray(compressionMimeTypes, response.getContentType())) {
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compressibleMimeType = true;
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if (debug > 0) {
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System.out.println("mime type " + response.getContentType() + " is compressible");
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}
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} else {
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if (debug > 0) {
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System.out.println("mime type " + response.getContentType() + " is not compressible");
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}
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}
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}
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if (response.isCommitted()) {
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if (debug > 1) {
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System.out.print("Response already committed. Using original output stream");
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}
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gzipstream = output;
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} else if (alreadyCompressed) {
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if (debug > 1) {
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System.out.print("Response already compressed. Using original output stream");
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}
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gzipstream = output;
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} else if (!compressibleMimeType) {
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if (debug > 1) {
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System.out.print("Response mime type is not compressible. Using original output stream");
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}
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gzipstream = output;
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} else {
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response.addHeader("Content-Encoding", "gzip");
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response.setContentLength(-1); // don't use any preset content-length as it will be wrong after gzipping
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response.setBufferSize(compressionBuffer);
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gzipstream = new GZIPOutputStream(output);
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}
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}
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gzipstream.write(b, off, len);
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}
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// -------------------------------------------------------- Package Methods
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/**
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* Has this response stream been closed?
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*
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* @return <code>true</code> if the stream has been closed, otherwise false.
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*/
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public boolean closed() {
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return closed;
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}
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/**
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* Checks if any entry in the string array starts with the specified value
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*
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* @param sArray the StringArray
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* @param value string
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*/
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private boolean startsWithStringArray(String sArray[], String value) {
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if (value == null) {
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return false;
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}
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for (String s : sArray) {
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if (value.startsWith(s)) {
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return true;
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}
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}
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return false;
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}
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}
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