自定义JSP防重复提交标签

package com.hhwy.tag;

import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.tagext.TagSupport;
import java.io.IOException;
import java.util.UUID;

/**
 * <br>描 述：防止重复提交
 * <br>创 建 人：Jinzhaoqiang
 * <br>创建时间： 20181120
 * <br>修改备注：无
 *   String token = request.getParameter("token");// 获取用户表单中提交的
    String pageToken = (String) request.getSession().getAttribute("token");
    if (token.equals(pageToken)) {
       // 令牌只能使用一次
       request.getSession().removeAttribute("token");
       //..业务处理
    } else {
      System.err.println("不能重复提交");
    }
 * <br>版本：1.0.0
 */
public class TokenTag extends TagSupport {
   @Override
   public int doStartTag() throws JspException {
      String uuid = UUID.randomUUID().toString().replace("-", "");
      pageContext.getSession().setAttribute("token", uuid);
      // 向页面上输出
      JspWriter out = pageContext.getOut();
      try {
         String html = "<input type='hidden' value='" + uuid + "' name='token'/>";
         out.print(html);
         //out.clear(); 会将该标签之前的内容清除
         out = pageContext.pushBody();
      } catch (Exception e) {
         e.printStackTrace();
      }finally {
         try {
            out.close();
         } catch (IOException e) {
            e.printStackTrace();
         }
      }
      return EVAL_BODY_INCLUDE;
   }
}

stm.tld

<?xml version="1.0" encoding="UTF-8" ?>
<taglib 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-jsptaglibrary_2_1.xsd"
   version="2.1">
   <!-- 标签的版本 -->
   <tlib-version>1.0</tlib-version>
   <!-- 声明标签的名称 -->
   <short-name>stm</short-name>
   <!-- 声明标签的引用方式标识符号 -->
   <uri>/stm.com</uri>
   <!-- 声明自己的标签 -->
   <tag>
      <name>token</name>
      <tag-class>com.hhwy.tag.TokenTag</tag-class>
      <body-content>JSP</body-content>
   </tag>
</taglib>

jsp

<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="UTF-8"%>
<%@ taglib uri="/stm.com" prefix="stm"%>
<!DOCTYPE HTML>
<html>
   <head>
      <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
      <meta http-equiv="X-UA-Compatible" content="IE=Edge,Chrome" />
      <title></title>
   </head>
   <body>
      首页
      <stm:token></stm:token>
      这是body
   </body>
</html>

自定义JSP防重复提交标签

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