Request的Body只能读取一次解决方法

一、需要一个类继承HttpServletRequestWrapper，该类继承了ServletRequestWrapper并实现了HttpServletRequest，

因此它可作为request在FilterChain中传递。

该类需要重写getReader和getInputStream两个方法，并在返回时将读出的body数据重新写入。

二、需要一个Filter筛选目标urlPattern，调用第一个类的同时，将第一个类写入FilterChain中代替原本的Request

package com.bonc.util;

import javax.servlet.ReadListener;
import javax.servlet.ServletInputStream;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletRequestWrapper;
import java.io.*;

public class BodyReaderRequestWrapper extends HttpServletRequestWrapper {
   private final String body;

   /**
    *
    * @param request
    */
   public BodyReaderRequestWrapper(HttpServletRequest request) throws IOException{
       super(request);
       StringBuilder sb = new StringBuilder();
       InputStream ins = request.getInputStream();
       BufferedReader isr = null;
       try{
           if(ins != null){
               isr = new BufferedReader(new InputStreamReader(ins));
               char[] charBuffer = new char[128];
               int readCount = 0;
               while((readCount = isr.read(charBuffer)) != -1){
                   sb.append(charBuffer,0,readCount);
               }
           }else{
               sb.append("");
           }
       }catch (IOException e){
           throw e;
       }finally {
           if(isr != null) {
               isr.close();
           }
       }

       sb.toString();
       body = sb.toString();
   }

   @Override
   public BufferedReader getReader() throws IOException {
       return new BufferedReader(new InputStreamReader(this.getInputStream()));
   }

   @Override
   public ServletInputStream getInputStream() throws IOException {
       final ByteArrayInputStream byteArrayIns = new ByteArrayInputStream(body.getBytes());
       ServletInputStream servletIns = new ServletInputStream() {
           @Override
           public boolean isFinished() {
               return false;
           }

           @Override
           public boolean isReady() {
               return false;
           }

           @Override
           public void setReadListener(ReadListener readListener) {

           }

           @Override
           public int read() throws IOException {
               return byteArrayIns.read();
           }
       };
       return  servletIns;
   }
}

package com.bonc.bitwd.filter;

import com.bonc.util.BodyReaderRequestWrapper;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

public class BodyReaderRequestFilter implements Filter{
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

    }

    @Override
    public void doFilter(ServletRequest req, ServletResponse res, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest)req;
        HttpServletResponse response = (HttpServletResponse)res;
        BodyReaderRequestWrapper requestWrapper  = new BodyReaderRequestWrapper(request);
        if(requestWrapper == null){
            filterChain.doFilter(request,response);
        }else {
            filterChain.doFilter(requestWrapper,response);
        }
    }

    @Override
    public void destroy() {

    }
}