全站压缩 过滤器，全站过滤器,服务器端用过滤器做全站压

全站压缩 过滤器，全站过滤器,服务器端用过滤器做全站压

服务器端用过滤器做全站压缩，节省流量

package cn.itcast.filter;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.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 destroy() {    }    public void doFilter(ServletRequest request, ServletResponse response,            FilterChain chain) throws IOException, ServletException {        //要想压缩页面 就是当用户访问页面时 在服务器把页面信息打给浏览器的时候进行压缩 所以这时候就是对response进行包装        MyResponse myresponse = new MyResponse((HttpServletResponse) response);        chain.doFilter(request, (ServletResponse) myresponse);        //从包装的myresponse里获得写到容器流里的原始数据bs        byte[] bs = myresponse.getOut();        System.out.println("压缩前>>>"+bs.length);        //用原始的response响应用户，此response需要转换为HttpServletResponse类型        HttpServletResponse resp = (HttpServletResponse) response;        //response解决中文乱码问题        resp.setContentType("text/html;charset=utf-8");        //开始压缩        ByteArrayOutputStream out = new ByteArrayOutputStream();        GZIPOutputStream zip = new GZIPOutputStream(out);        zip.write(bs);        zip.close();        //获取压缩后的数据        byte[] dest = out.toByteArray();        System.out.println("压缩后>>>"+dest.length);        //设置响应头        resp.setDateHeader("content-length", dest.length);        resp.setHeader("content-Encoding", "gzip");        resp.getOutputStream().write(dest);    }    public void init(FilterConfig arg0) throws ServletException {    }}class MyResponse extends HttpServletResponseWrapper{    private ByteArrayOutputStream out = new ByteArrayOutputStream();//定义一个容器    public MyResponse(HttpServletResponse response) {        super(response);    }    //重写父类的getwriter方法     PrintWriter writer;    @Override    public PrintWriter getWriter() throws IOException {        //写到一个容器流里  ，        writer = new PrintWriter(new OutputStreamWriter(out,"utf-8"), true);        return writer;    }    //提供一个获得流里内容的方法    因为用字符流写到容器里的，有缓冲区,所以在取出流里的数据时判断字符流是否关闭    public byte[] getOut(){        if(writer!=null){            writer.close();        }        return out.toByteArray();    }   }<?xml version="1.0" encoding="UTF-8"?><web-app version="2.5"    xmlns="http://java.sun.com/xml/ns/javaee"    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee     http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">  <display-name></display-name>   <filter>    <filter-name>GZIP</filter-name>    <filter-class>cn.itcast.filter.GZIPFilter</filter-class>  </filter>  <filter-mapping>    <filter-name>GZIP</filter-name>    <url-pattern>*.jsp</url-pattern>  </filter-mapping>  <welcome-file-list>    <welcome-file>index.jsp</welcome-file>  </welcome-file-list></web-app>//该片段来自于http://byrx.net