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shiwj1010
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防止jsp表单重复提交，不用框架，自定义一个

    博客分类：
  • j2ee
框架JSPServletJavaSecurity
阅读更多 
<%@ page contentType="text/html; charset=GBK"%>

<%
    TokenProcessor tokemProcessor=TokenProcessor.getInstance();
        tokemProcessor.saveToken(request);
    String token=(String)request.getSession().getAttribute(tokemProcessor.FORM_TOKEN_KEY);
 %>
<html>
    <head>
        <title>用户登陆</title>
    </head>
    <body>
        <form action="/testServlet" method="post">
          <input name="<%=tokemProcessor.FORM_TOKEN_KEY %>" value="<%=token %>">
          <input name="q"/>
          
          <input type="submit" value="submit"/>
        </form>
    </body>
</html>


生成token,主要工具类 
import java.securITy.MessageDigest;
import java.security.NoSuchAlgorithmException;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;


public class TokenProcessor {
   private long privious;//上次生成表单标识号得时间值
   private static TokenProcessor instance=new TokenProcessor();
   public static String FORM_TOKEN_KEY="FORM_TOKEN_KEY";
   private TokenProcessor(){
       
   }
   public static TokenProcessor getInstance(){
       return instance;
   }
   /**//*
    * 验证请求中得标识号是否有效，如果请求中的表单标识与当前用户session中的相同，返回结果true=
    */
   public synchronized boolean isTokenValid(HttpServletRequest request){
       //未避免session对象不存在时候创建Session对象
       HttpSession session=request.getSession(false);
       if(session==null){return false;}
       String saved=(String)session.getAttribute(FORM_TOKEN_KEY);
       if(saved==null){
           return false;
       }
       String token=(String)request.getParameter(FORM_TOKEN_KEY);
       if(token==null){
           return false;
       }
       return saved.equals(token);
   }
   
   /**//*
    * 清楚存储在当前用户session中的表单标识号
    */
   public synchronized void reset(HttpServletRequest request){
       HttpSession session=request.getSession(false);
       if(session==null){
           return;
       }
       session.removeAttribute(FORM_TOKEN_KEY);
   }
   
   /**//*
    * 产生表单标识号并将之保存在当前用户得session中
    */
   
   public synchronized void saveToken(HttpServletRequest request){
       HttpSession session=request.getSession();
       try {
        byte id[]=session.getId().getBytes();
        long current=System.currentTimeMillis();
        if(current==privious){
            current++;
        }
        privious=current;
        byte now[]=String.valueOf(current).getBytes();
        MessageDigest md=MessageDigest.getInstance("MD5");
        md.update(id);
        md.update(now);
        String token=toHex(md.digest());
        session.setAttribute(FORM_TOKEN_KEY, token);
      } catch (NoSuchAlgorithmException e) {
        
      }
   }
   /**//*
    * 将一个字节数转换成十六进制得字符串
    * 
    */
   public String toHex(byte buffer[]){
       StringBuffer sb=new StringBuffer(buffer.length*2);
       for (int i = 0; i < buffer.length; i++) {
        sb.append(Character.forDigit((buffer[i]&0x60)>>4, 16));
        sb.append(Character.forDigit(buffer[i]&0x0f, 16));
    }
       return sb.toString();
       
   }
}


提交处理 
import java.io.IOException;
import java.io.PrintWrITer;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;


public class FormDoubleServlet extends HttpServlet {
    
    protected void service(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        response.setContentType("text/html;charset=gb2312");
        PrintWriter out=response.getWriter();
        TokenProcessor tokemProcessor=TokenProcessor.getInstance();
        if(!tokemProcessor.isTokenValid(request)){
            out.println("重复提交");
        }
        String p1=request.getParameter("p");
        if(p1==null||p1.trim().equals("")){
            out.println("请输入内容");
        }else{
            out.println("提交内容被处理");
            tokemProcessor.reset(request);//清楚session中的标识
        }
        
    }
}
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