使用动态代理进行GZIP数据压缩过滤

import java.io.ByteArrayOutputStream;import java.io.IOException;import java.io.OutputStreamWriter;import java.io.PrintWriter;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;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;//采用动态代理进行Gzip过滤public class GzipFilterProxy implements Filter {public void destroy() {// TODO Auto-generated method stub}public void doFilter(ServletRequest req, ServletResponse res,FilterChain chain) throws IOException, ServletException {// TODO Auto-generated method stubHttpServletRequest request = (HttpServletRequest) req;final HttpServletResponse response = (HttpServletResponse) res;final ByteArrayOutputStream bout = new ByteArrayOutputStream();final PrintWriter pw = new PrintWriter(new OutputStreamWriter(bout,response.getCharacterEncoding()));chain.doFilter(request, (ServletResponse) Proxy.newProxyInstance(this.getClass().getClassLoader(), response.getClass().getInterfaces(), new InvocationHandler() {@Overridepublic Object invoke(Object proxy, Method method, Object[] args)throws Throwable {String methodname = method.getName();if (methodname.equals("getOutputStream")) {//如果调用getOutputStream()方法，则返回保存了数据的字节数据流return new MyServletOutputStream(bout);} else if (methodname.equals("getWriter")) {//如果调用getWriter()方法，则返回保存了数据的PrintWriter流return pw;} else {return method.invoke(response, args);}}}));//Pintwriter 存在缓冲，调用之前进行缓存清空，字节缓冲才能才能得到数据if (pw != null) {pw.close();}byte data[] = bout.toByteArray();System.out.println("原始大小：" + data.length);byte[] gzip = gzip(data);//告诉浏览器获得的数据是压缩后的数据response.setHeader("content-encoding", "gzip");response.setHeader("content-length", gzip.length + "");response.getOutputStream().write(gzip);}//进行数据压缩private byte[] gzip(byte[] data) throws IOException {ByteArrayOutputStream bout = new ByteArrayOutputStream();GZIPOutputStream gout = new GZIPOutputStream(bout);gout.write(data);gout.close();return bout.toByteArray();}//创建ServletOutputStream子类，覆盖write方法，从而使数据写到字节数组中class MyServletOutputStream extends ServletOutputStream {private ByteArrayOutputStream bout;public MyServletOutputStream(ByteArrayOutputStream bout) {this.bout = bout;}@Overridepublic void write(int b) throws IOException {// TODO Auto-generated method stubbout.write(b);}}public void init(FilterConfig filterConfig) throws ServletException {// TODO Auto-generated method stub}}