Compression Servlet Response Wrapper
/*
* Copyright 2004 The Apache Software Foundation
*
* Licensed 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.
*/
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.Locale;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletResponse;
import javax.servlet.ServletResponseWrapper;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
/**
* Implementation of <b>HttpServletResponseWrapper</b> that works with
* the CompressionServletResponseStream implementation..
*
* @author Amy Roh
* @author Dmitri Valdin
* @version $Revision: 1.3 $, $Date: 2004/03/18 16:40:33 $
*/
public class CompressionServletResponseWrapper extends HttpServletResponseWrapper {
// ----------------------------------------------------- Constructor
/**
* Calls the parent constructor which creates a ServletResponse adaptor
* wrapping the given response object.
*/
public CompressionServletResponseWrapper(HttpServletResponse response) {
super(response);
origResponse = response;
if (debug > 1) {
System.out.println("CompressionServletResponseWrapper constructor gets called");
}
}
// ----------------------------------------------------- Instance Variables
/**
* Original response
*/
protected HttpServletResponse origResponse = null;
/**
* Descriptive information about this Response implementation.
*/
protected static final String info = "CompressionServletResponseWrapper";
/**
* The ServletOutputStream that has been returned by
* <code>getOutputStream()</code>, if any.
*/
protected ServletOutputStream stream = null;
/**
* The PrintWriter that has been returned by
* <code>getWriter()</code>, if any.
*/
protected PrintWriter writer = null;
/**
* The threshold number to compress
*/
protected int threshold = 0;
/**
* Debug level
*/
private int debug = 0;
/**
* Content type
*/
protected String contentType = null;
// --------------------------------------------------------- Public Methods
/**
* Set content type
*/
public void setContentType(String contentType) {
if (debug > 1) {
System.out.println("setContentType to "+contentType);
}
this.contentType = contentType;
origResponse.setContentType(contentType);
}
/**
* Set threshold number
*/
public void setCompressionThreshold(int threshold) {
if (debug > 1) {
System.out.println("setCompressionThreshold to " + threshold);
}
this.threshold = threshold;
}
/**
* Set debug level
*/
public void setDebugLevel(int debug) {
this.debug = debug;
}
/**
* Create and return a ServletOutputStream to write the content
* associated with this Response.
*
* @exception IOException if an input/output error occurs
*/
public ServletOutputStream createOutputStream() throws IOException {
if (debug > 1) {
System.out.println("createOutputStream gets called");
}
CompressionResponseStream stream = new CompressionResponseStream(origResponse);
stream.setDebugLevel(debug);
stream.setBuffer(threshold);
return stream;
}
/**
* Finish a response.
*/
public void finishResponse() {
try {
if (writer != null) {
writer.close();
} else {
if (stream != null)
stream.close();
}
} catch (IOException e) {
}
}
// ------------------------------------------------ ServletResponse Methods
/**
* Flush the buffer and commit this response.
*
* @exception IOException if an input/output error occurs
*/
public void flushBuffer() throws IOException {
if (debug > 1) {
System.out.println("flush buffer @ CompressionServletResponseWrapper");
}
((CompressionResponseStream)stream).flush();
}
/**
* Return the servlet output stream associated with this Response.
*
* @exception IllegalStateException if <code>getWriter</code> has
* already been called for this response
* @exception IOException if an input/output error occurs
*/
public ServletOutputStream getOutputStream() throws IOException {
if (writer != null)
throw new IllegalStateException("getWriter() has already been called for this response");
if (stream == null)
stream = createOutputStream();
if (debug > 1) {
System.out.println("stream is set to "+stream+" in getOutputStream");
}
return (stream);
}
/**
* Return the writer associated with this Response.
*
* @exception IllegalStateException if <code>getOutputStream</code> has
* already been called for this response
* @exception IOException if an input/output error occurs
*/
public PrintWriter getWriter() throws IOException {
if (writer != null)
return (writer);
if (stream != null)
throw new IllegalStateException("getOutputStream() has already been called for this response");
stream = createOutputStream();
if (debug > 1) {
System.out.println("stream is set to "+stream+" in getWriter");
}
//String charset = getCharsetFromContentType(contentType);
String charEnc = origResponse.getCharacterEncoding();
if (debug > 1) {
System.out.println("character encoding is " + charEnc);
}
// HttpServletResponse.getCharacterEncoding() shouldn't return null
// according the spec, so feel free to remove that "if"
if (charEnc != null) {
writer = new PrintWriter(new OutputStreamWriter(stream, charEnc));
} else {
writer = new PrintWriter(stream);
}
return (writer);
}
public void setContentLength(int length) {
}
/**
* Returns character from content type. This method was taken from tomcat.
* @author rajo
*/
private static String getCharsetFromContentType(String type) {
if (type == null) {
return null;
}
int semi = type.indexOf(";");
if (semi == -1) {
return null;
}
String afterSemi = type.substring(semi + 1);
int charsetLocation = afterSemi.indexOf("charset=");
if(charsetLocation == -1) {
return null;
} else {
String afterCharset = afterSemi.substring(charsetLocation + 8);
String encoding = afterCharset.trim();
return encoding;
}
}
}
/// the visibility of variables declared at class level and within methods.
class HW {
int j; // j is visible to both method1 and method 2
void method1() {
double x; // x is visible only to method1
}
void method2() {
double y; // y is visible only to method2
}
}
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