Mega Code Archive
GZIP Filter, response stream and Response Wrapper
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/*
* Copyright 2003 Jayson Falkner (jayson@jspinsider.com)
* This code is from "Servlets and JavaServer pages; the J2EE Web Tier",
* http://www.jspbook.com. You may freely use the code both commercially
* and non-commercially. If you like the code, please pick up a copy of
* the book and help support the authors, development of more free code,
* and the JSP/Servlet/J2EE community.
*/
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.zip.GZIPOutputStream;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
public class GZIPFilter implements Filter {
public void doFilter(ServletRequest req, ServletResponse res,
FilterChain chain) throws IOException, ServletException {
if (req instanceof HttpServletRequest) {
HttpServletRequest request = (HttpServletRequest) req;
HttpServletResponse response = (HttpServletResponse) res;
String ae = request.getHeader("accept-encoding");
if (ae != null && ae.indexOf("gzip") != -1) {
GZIPResponseWrapper wrappedResponse = new GZIPResponseWrapper(response);
chain.doFilter(req, wrappedResponse);
wrappedResponse.finishResponse();
return;
}
chain.doFilter(req, res);
}
}
public void init(FilterConfig filterConfig) {
// noop
}
public void destroy() {
// noop
}
}
/*
* Copyright 2003 Jayson Falkner (jayson@jspinsider.com)
* This code is from "Servlets and JavaServer pages; the J2EE Web Tier",
* http://www.jspbook.com. You may freely use the code both commercially
* and non-commercially. If you like the code, please pick up a copy of
* the book and help support the authors, development of more free code,
* and the JSP/Servlet/J2EE community.
*/
class GZIPResponseStream extends ServletOutputStream {
protected ByteArrayOutputStream baos = null;
protected GZIPOutputStream gzipstream = null;
protected boolean closed = false;
protected HttpServletResponse response = null;
protected ServletOutputStream output = null;
public GZIPResponseStream(HttpServletResponse response) throws IOException {
super();
closed = false;
this.response = response;
this.output = response.getOutputStream();
baos = new ByteArrayOutputStream();
gzipstream = new GZIPOutputStream(baos);
}
public void close() throws IOException {
if (closed) {
throw new IOException("This output stream has already been closed");
}
gzipstream.finish();
byte[] bytes = baos.toByteArray();
response.addHeader("Content-Length",
Integer.toString(bytes.length));
response.addHeader("Content-Encoding", "gzip");
output.write(bytes);
output.flush();
output.close();
closed = true;
}
public void flush() throws IOException {
if (closed) {
throw new IOException("Cannot flush a closed output stream");
}
gzipstream.flush();
}
public void write(int b) throws IOException {
if (closed) {
throw new IOException("Cannot write to a closed output stream");
}
gzipstream.write((byte)b);
}
public void write(byte b[]) throws IOException {
write(b, 0, b.length);
}
public void write(byte b[], int off, int len) throws IOException {
if (closed) {
throw new IOException("Cannot write to a closed output stream");
}
gzipstream.write(b, off, len);
}
public boolean closed() {
return (this.closed);
}
public void reset() {
//noop
}
}
/*
* Copyright 2003 Jayson Falkner (jayson@jspinsider.com)
* This code is from "Servlets and JavaServer pages; the J2EE Web Tier",
* http://www.jspbook.com. You may freely use the code both commercially
* and non-commercially. If you like the code, please pick up a copy of
* the book and help support the authors, development of more free code,
* and the JSP/Servlet/J2EE community.
*/
class GZIPResponseWrapper extends HttpServletResponseWrapper {
protected HttpServletResponse origResponse = null;
protected ServletOutputStream stream = null;
protected PrintWriter writer = null;
public GZIPResponseWrapper(HttpServletResponse response) {
super(response);
origResponse = response;
}
public ServletOutputStream createOutputStream() throws IOException {
return (new GZIPResponseStream(origResponse));
}
public void finishResponse() {
try {
if (writer != null) {
writer.close();
} else {
if (stream != null) {
stream.close();
}
}
} catch (IOException e) {}
}
public void flushBuffer() throws IOException {
stream.flush();
}
public ServletOutputStream getOutputStream() throws IOException {
if (writer != null) {
throw new IllegalStateException("getWriter() has already been called!");
}
if (stream == null)
stream = createOutputStream();
return (stream);
}
public PrintWriter getWriter() throws IOException {
if (writer != null) {
return (writer);
}
if (stream != null) {
throw new IllegalStateException("getOutputStream() has already been called!");
}
stream = createOutputStream();
writer = new PrintWriter(new OutputStreamWriter(stream, "UTF-8"));
return (writer);
}
public void setContentLength(int length) {}
}
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