java过滤器中修改一个http请求的返回内容.docx

java在过滤器中修改一个http请求的返回内容response保存了请求的返回信息,里面有个outputstream,你要返回给页面的流,都在这个地方保存.sun为我们提供了这么一个工具HttpServletResponseWrapper抽象类,利用这个类的子类把servletresponse包装一下,在过滤器中使用,就可以去除response的文件流,对其作出修改.首先要先子类化HttpServletResponseWrapper。 先子类化HttpServletResponseWrapper1、获取response对象，并将输出存放在自定义的流里面，那么关于输出流（outputStream、writer）的操作都是需要重写的了： 1）以流的方式获取输出重写getOutputStrem() 2）以字符方式获取输出重写getWriter() 3）刷新流重写flushBuffer() 4）重置流重写reset() 然后加入新增的获取输出数据的方法就ok了。2、定义response包装器WapperedResponse继承HttpServletResponseWrapperimport java.io.ByteArrayOutputStream;import java.io.CharArrayWriter;import java.io.IOException;import java.io.PrintWriter;import java.io.UnsupportedEncodingException;import javax.servlet.ServletOutputStream;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpServletResponseWrapper;public class ResponseWrapper extends HttpServletResponseWrapper private PrintWriter cachedWriter; private CharArrayWriter bufferedWriter; private ServletOutputStream out=null; public ResponseWrapper(HttpServletResponse response) throws IOException super(response); / 这个是我们保存返回结果的地方 bufferedWriter = new CharArrayWriter(); out=new WapperedOutputStream(bufferedWriter); / 这个是包装PrintWriter的，让所有结果通过这个PrintWriter写入到bufferedWriter中 cachedWriter = new PrintWriter(bufferedWriter); /重载父类获取writer的方法 Override public PrintWriter getWriter() throws UnsupportedEncodingException return cachedWriter; /重载父类获取outputstream的方法 Override public ServletOutputStream getOutputStream()throws IOException return out; /重载父类获取flushBuffer的方法 Override public void flushBuffer()throws IOException if(out!=null) out.flush(); if(cachedWriter!=null) cachedWriter.flush(); Override public void reset() bufferedWriter.reset(); /* * 获取原始的HTML页面内容。 * return */ public String getResult() throws IOException flushBuffer(); return bufferedWriter.toString(); /内部类，对ServletOutputStream进行包装 private class WapperedOutputStream extends ServletOutputStream private CharArrayWriter bos=null; public WapperedOutputStream(CharArrayWriter stream) throws IOException bos=stream; Override public void write(int b) throws IOException bos.write(b); 然后在过滤器中使用，如下：import java.io.IOException;import java.io.PrintWriter;import java.util.regex.Matcher;import java.util.regex.Pattern;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.HttpServletResponse;public class InitLabelParamSidFilter implements FilterOverridepublic void destroy() / TODO Auto-generated method stubOverridepublic void doFilter(ServletRequest request, ServletResponse response,FilterChain chain) throws IOException, ServletException request.setCharacterEncoding(utf-8); PrintWriter out = null;try / 使用我们自定义的响应包装器来包装原始的ServletResponse ResponseWrapper wrapper = new ResponseWrapper(HttpServletResponse)response); chain.doFilter(request, wrapper); String result = wrapper.getResult(); result=getDealContent(result,request); response.setContentLength(-1); out = response.getWriter();/ 输出最终的结果 out.write(result);catch(Exception e)e.printStackTrace();finally try if (out != null) out.flush(); ou