Можно и написать. Где-то давно уже стащил, вроде бы из какой-то книги, так и пользуюсь.
| Код |
package com.domain.filters;
import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
public class GZIPFilter implements Filter {
protected static final Log logger = LogFactory.getLog(GZIPFilter.class);
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) {
logger.debug("GZIP supported, compressing.");
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
}
}
|
| Код |
package com.domain.filters;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.zip.GZIPOutputStream;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
public class GZIPResponseStream extends ServletOutputStream {
// abstraction of the output stream used for compression
protected OutputStream bufferedOutput = null;
// state keeping variable for if close() has been called
protected boolean closed = false;
// reference to original response
protected HttpServletResponse response = null;
// reference to the output stream to the client's browser
protected ServletOutputStream output = null;
// default size of the in-memory buffer
private int bufferSize = 50000;
public GZIPResponseStream(HttpServletResponse response) throws IOException {
super();
closed = false;
this.response = response;
this.output = response.getOutputStream();
bufferedOutput = new ByteArrayOutputStream();
}
public void close() throws IOException {
// This hack shouldn't be needed, but it seems to make JBoss and Struts
// like the code more without hurting anything.
/*
* // verify the stream is yet to be closed if (closed) { throw new
* IOException("This output stream has already been closed"); }
*/
// if we buffered everything in memory, gzip it
if (bufferedOutput instanceof ByteArrayOutputStream) {
// get the content
ByteArrayOutputStream baos = (ByteArrayOutputStream) bufferedOutput;
// prepare a gzip stream
ByteArrayOutputStream compressedContent = new ByteArrayOutputStream();
GZIPOutputStream gzipstream = new GZIPOutputStream(
compressedContent);
byte[] bytes = baos.toByteArray();
gzipstream.write(bytes);
gzipstream.finish();
// get the compressed content
byte[] compressedBytes = compressedContent.toByteArray();
// set appropriate HTTP headers
response.setContentLength(compressedBytes.length);
response.addHeader("Content-Encoding", "gzip");
output.write(compressedBytes);
output.flush();
output.close();
closed = true;
}
// if things were not buffered in memory, finish the GZIP stream and
// response
else if (bufferedOutput instanceof GZIPOutputStream) {
// cast to appropriate type
GZIPOutputStream gzipstream = (GZIPOutputStream) bufferedOutput;
// finish the compression
gzipstream.finish();
// finish the response
output.flush();
output.close();
closed = true;
}
}
public void flush() throws IOException {
if (closed) {
throw new IOException("Cannot flush a closed output stream");
}
bufferedOutput.flush();
}
public void write(int b) throws IOException {
if (closed) {
throw new IOException("Cannot write to a closed output stream");
}
// make sure we aren't over the buffer's limit
checkBufferSize(1);
// write the byte to the temporary output
bufferedOutput.write((byte) b);
}
private void checkBufferSize(int length) throws IOException {
// check if we are buffering too large of a file
if (bufferedOutput instanceof ByteArrayOutputStream) {
ByteArrayOutputStream baos = (ByteArrayOutputStream) bufferedOutput;
if (baos.size() + length > bufferSize) {
// files too large to keep in memory are sent to the client
// without Content-Length specified
response.addHeader("Content-Encoding", "gzip");
// get existing bytes
byte[] bytes = baos.toByteArray();
// make new gzip stream using the response output stream
GZIPOutputStream gzipstream = new GZIPOutputStream(output);
gzipstream.write(bytes);
// we are no longer buffering, send content via gzipstream
bufferedOutput = gzipstream;
}
}
}
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");
}
// make sure we aren't over the buffer's limit
checkBufferSize(len);
// write the content to the buffer
bufferedOutput.write(b, off, len);
}
public boolean closed() {
return (this.closed);
}
public void reset() {
// noop
}
}
|
| Код |
package com.domain.filters;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import javax.servlet.ServletOutputStream;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletResponseWrapper;
public 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();
// BUG FIX 2003-12-01 Reuse content's encoding, don't assume UTF-8
writer = new PrintWriter(new OutputStreamWriter(stream, origResponse
.getCharacterEncoding()));
return (writer);
}
public void setContentLength(int length) {
}
}
|
В web.xml
| Код |
<filter>
<filter-name>GZIPFilter</filter-name>
<filter-class>com.domain.filters.GZIPFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>GZIPFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
|
Теоретически должно работать на любом сервере. У меня работает и на Tomcat 5.5 и на Resin 3.0 |
