使用HttpServletResponseWrapper截獲返回數據流

在Java Web開發中，咱們常常須要攔截http請求，去作一些轉發或者是校驗等事情。這類工做一般filter能夠很輕鬆的搞定，但這通常都是攔截請求。而咱們有時候也會有一些需求，好比說是攔截服務器的返回(Response)，但願在數據流在服務器端處理完畢，且返回瀏覽器以前，在這中間作一些本身的事情。網上搜了搜，發現資源不多。因而本身實現了一版，跟你們分享一下。主要用到了HttpServletResponseWrapper獲取到數據流，而後經過response.getWriter().write來回寫數據。

  1 HttpStreamFilter.java
  2 
  3 package test;
  4 
  5 import java.io.BufferedReader;
  6 import java.io.FileReader;
  7 import java.io.File;
  8 import java.io.IOException;
  9 import javax.servlet.Filter;
 10 import javax.servlet.FilterChain;
 11 import javax.servlet.FilterConfig;
 12 import javax.servlet.ServletException;
 13 import javax.servlet.ServletRequest;
 14 import javax.servlet.ServletResponse;
 15 import javax.servlet.http.HttpServletRequest;
 16 import javax.servlet.http.HttpServletResponse;
 17 import java.util.regex.Pattern;
 18 import java.util.regex.Matcher;
 19 import java.util.concurrent.ConcurrentHashMap;
 20 
 21 public class HttpStreamFilter  implements Filter {
 22 
 23     public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain chain) 
 24 throws IOException, ServletException
 25     {
 26         HttpServletRequest request = (HttpServletRequest)arg0;
 27         HttpServletResponse response = (HttpServletResponse)arg1;
 28      
 29         WrapperResponse wrapperResponse = new WrapperResponse(response);
 30         chain.doFilter(request, wrapperResponse);
 31         String html = wrapperResponse.getContent();
 32         response.setContentLength(-1);
 33         response.getWriter().write( filterHTML(html) );
 34     }
 35 
 36     public void init(FilterConfig filterConfig) throws ServletException {
 37     
 38     }
 39 
 40     public void destroy() {}
 41 
 42     public String filterHTML(String html) throws IOException
 43     {
 44         return html.replace("script", "");
 45     }
 46 }    
 47 WrapperResponse.java
 48 
 49 package test;
 50 
 51 import java.io.ByteArrayOutputStream;
 52 import java.io.IOException;
 53 import java.io.PrintWriter;
 54 import java.io.UnsupportedEncodingException;
 55 import javax.servlet.http.HttpServletResponse;
 56 import javax.servlet.http.HttpServletResponseWrapper;
 57 
 58 public class WrapperResponse extends HttpServletResponseWrapper {
 59 
 60     private class ResponsePrintWriter extends PrintWriter
 61     {
 62         ByteArrayOutputStream output;
 63 
 64         public ResponsePrintWriter(ByteArrayOutputStream output)
 65         {
 66             super(output);
 67             this.output = output;
 68         }
 69 
 70         public ByteArrayOutputStream getByteArrayOutputStream()
 71         {
 72             return output;
 73         }
 74     }
 75 
 76     private ResponsePrintWriter writer;
 77     private ByteArrayOutputStream output;
 78 
 79     public WrapperResponse(HttpServletResponse httpServletResponse)
 80     {
 81         super(httpServletResponse);
 82         output = new ByteArrayOutputStream();
 83         writer = new ResponsePrintWriter(output);
 84     }
 85 
 86     public void finalize() throws Throwable
 87     {
 88         super.finalize();
 89         output.close();
 90         writer.close();
 91     }
 92 
 93     public String getContent()
 94     {
 95         try
 96         {
 97             writer.flush();
 98             return writer.getByteArrayOutputStream().toString("GBK");
 99         }
100         catch(UnsupportedEncodingException e)
101         {
102             return "UnsupportedEncoding";
103         }
104     }
105 
106     public void close() throws IOException
107     {
108         writer.close();
109     }
110 
111     public PrintWriter getWriter() throws IOException
112     {
113         return writer;
114     }
115 }