/*
* 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 compressionFilters;
import java.io.IOException;
import java.io.OutputStream;
import java.util.zip.GZIPOutputStream;
import javax.servlet.ServletOutputStream;
/**
* Implementation of <b>ServletOutputStream</b> that works with
* the CompressionServletResponseWrapper implementation.
*
* @author Amy Roh
* @author Dmitri Valdin
*/
public class CompressionResponseStream extends ServletOutputStream {
// ----------------------------------------------------------- Constructors
/**
* Construct a servlet output stream associated with the specified Response.
*
* @param responseWrapper The associated response wrapper
* @param originalOutput the output stream
*/
public CompressionResponseStream(
CompressionServletResponseWrapper responseWrapper,
ServletOutputStream originalOutput) {
super();
closed = false;
this.response = responseWrapper;
this.output = originalOutput;
}
// ----------------------------------------------------- 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 compression buffer size to avoid chunking
*/
protected int compressionBuffer = 0;
/**
* The mime types to compress
*/
protected String[] compressionMimeTypes = {"text/html", "text/xml", "text/plain"};
/**
* Debug level
*/
private int debug = 0;
/**
* The buffer through which all of our output bytes are passed.
*/
protected byte[] buffer = null;
/**
* The number of data bytes currently in the buffer.
*/
protected int bufferCount = 0;
/**
* The underlying gzip output stream to which we should write data.
*/
protected OutputStream gzipstream = null;
/**
* Has this stream been closed?
*/
protected boolean closed = false;
/**
* The content length past which we will not write, or -1 if there is
* no defined content length.
*/
protected int length = -1;
/**
* The response with which this servlet output stream is associated.
*/
protected CompressionServletResponseWrapper response = null;
/**
* The underlying servlet output stream to which we should write data.
*/
protected ServletOutputStream output = null;
// --------------------------------------------------------- Public Methods
/**
* Set debug level
*/
public void setDebugLevel(int debug) {
this.debug = debug;
}
/**
* Set the compressionThreshold number and create buffer for this size
*/
protected void setCompressionThreshold(int compressionThreshold) {
this.compressionThreshold = compressionThreshold;
buffer = new byte[this.compressionThreshold];
if (debug > 1) {
System.out.println("compressionThreshold is set to "+ this.compressionThreshold);
}
}
/**
* The compression buffer size to avoid chunking
*/
protected void setCompressionBuffer(int compressionBuffer) {
this.compressionBuffer = compressionBuffer;
if (debug > 1) {
System.out.println("compressionBuffer is set to "+ this.compressionBuffer);
}
}
/**
* Set supported mime types
*/
public void setCompressionMimeTypes(String[] compressionMimeTypes) {
this.compressionMimeTypes = compressionMimeTypes;
if (debug > 1) {
System.out.println("compressionMimeTypes is set to " + this.compressionMimeTypes);
}
}
/**
* Close this output stream, causing any buffered data to be flushed and
* any further output data to throw an IOException.
*/
@Override
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;
}
/**
* Flush any buffered data for this output stream, which also causes the
* response to be committed.
*/
@Override
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();
}
}
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
*/
@Override
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
*/
@Override
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
*/
@Override
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);
}
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");
}
boolean alreadyCompressed = false;
String contentEncoding = response.getHeader("Content-Encoding");
if (contentEncoding != null) {
if (contentEncoding.contains("gzip")) {
alreadyCompressed = true;
if (debug > 0) {
System.out.println("content is already compressed");
}
} else {
if (debug > 0) {
System.out.println("content is not compressed yet");
}
}
}
boolean compressibleMimeType = false;
// Check for compatible MIME-TYPE
if (compressionMimeTypes != null) {
if (startsWithStringArray(compressionMimeTypes, response.getContentType())) {
compressibleMimeType = true;
if (debug > 0) {
System.out.println("mime type " + response.getContentType() + " is compressible");
}
} else {
if (debug > 0) {
System.out.println("mime type " + response.getContentType() + " is not compressible");
}
}
}
if (response.isCommitted()) {
if (debug > 1)
System.out.print("Response already committed. Using original output stream");
gzipstream = output;
} else if (alreadyCompressed) {
if (debug > 1)
System.out.print("Response already compressed. Using original output stream");
gzipstream = output;
} else if (!compressibleMimeType) {
if (debug > 1)
System.out.print("Response mime type is not compressible. Using original output stream");
gzipstream = output;
} else {
response.addHeader("Content-Encoding", "gzip");
response.setContentLength(-1); // don't use any preset content-length as it will be wrong after gzipping
response.setBufferSize(compressionBuffer);
gzipstream = new GZIPOutputStream(output);
}
}
gzipstream.write(b, off, len);
}
// -------------------------------------------------------- Package Methods
/**
* Has this response stream been closed?
*/
public boolean closed() {
return (this.closed);
}
/**
* Checks if any entry in the string array starts with the specified value
*
* @param sArray the StringArray
* @param value string
*/
private boolean startsWithStringArray(String sArray[], String value) {
if (value == null)
return false;
for (int i = 0; i < sArray.length; i++) {
if (value.startsWith(sArray[i])) {
return true;
}
}
return false;
}
}