防止表单重复提交的思路

水深无声 2022-03-19 08:38 146阅读 0赞

面试时遇到一个题：怎么防止表单重复提交？

当时想了想，这个题不是很难，简单来说就是验证的问题。于是我很容易想到session。

因为session的原理和这个很像。

我的思路：在表单中加入隐藏字段，作为这个表单的唯一标识。同时再session中记录这个表单的提交次数。

下次再提交，就是重复提交的时候，从session中获取提交次数，判断一下就可以了。

下面给出我的例子：

先写一个简单的新增的操作。

IsRepeatSubmitAction

package org.test.submit.action;
    
    import java.io.PrintWriter;
    import java.util.Date;
    
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    import javax.servlet.http.HttpSession;
    
    import org.apache.struts2.ServletActionContext;
    import org.base.MyBaseAction;
    import org.base.pk.UUIDHexGenerator;
    import org.test.submit.bean.Develpoer;
    import org.test.submit.dao.SubmitDao;
    
    import com.opensymphony.xwork2.ActionContext;
    
    public class IsRepeatSubmitAction  extends MyBaseAction {
    	private static final long serialVersionUID = 1L;
    	
    	public String execute() throws Exception{
    		String pk_userId=(String)UUIDHexGenerator.generate();//生成主键
    		
    		this.getHttpServletRequest().setAttribute("userId", pk_userId);//放入页面表单的隐藏字段中
    		this.getHttpSession().setAttribute(pk_userId.trim(), 0);//放入session中
    		
    		return SUCCESS;
    	}	
    	public String goSubmit() throws Exception{
    		//
    		ActionContext ctx = ActionContext.getContext();
    		HttpServletResponse response = (HttpServletResponse) ctx.get(ServletActionContext.HTTP_RESPONSE); 
    		HttpServletRequest request  = (HttpServletRequest) ctx.get(ServletActionContext.HTTP_REQUEST);
    		HttpSession  session  = request.getSession();
    		response.setCharacterEncoding("UTF-8");
    		PrintWriter out = response.getWriter();
    		
    		String pk_userId_from_page="";//从页面的隐藏字段获取主键
    		if(this.getDevelpoer()==null){
    			System.out.println("获取表单错误！");
    		}else{
    			pk_userId_from_page=(this.getDevelpoer().getUserId()!=null)?(String)this.getDevelpoer().getUserId().trim():"";
    			if(pk_userId_from_page.equals("")){
    				System.out.println("传参错误！");
    			}else{
    				System.out.println("主键userId："+pk_userId_from_page);
    				if(this.getHttpSession().getAttribute(pk_userId_from_page)==null){
    					System.out.println("表单已过期！！");
    				}else{
    					int pk_userId_count=(Integer)this.getHttpSession().getAttribute(pk_userId_from_page);//获取该主键提交的次数(没提交是0；提交过是1)
    					if(pk_userId_count==0){
    						this.getHttpSession().setAttribute(pk_userId_from_page, 1);//置成1--已提交
    						String addres=submitDao.addDeveloper(this.getDevelpoer());//插入数据
    						if(addres.equals("success")){
    							System.out.println("成功写库！"+new Date().toString());
    						}else{
    							System.out.println("写库失败！请联系管理员！"+new Date().toString());
    						}
    					}else{
    						System.out.println("您已提交过表单！");
    					}
    				}
    				
    			}
    			
    		}
    		
    		return NONE;
    	}
    	
    	
    	
    	private SubmitDao submitDao;
    
    	public SubmitDao getSubmitDao() {
    		return submitDao;
    	}
    	public void setSubmitDao(SubmitDao submitDao) {
    		this.submitDao = submitDao;
    	}
    	private Develpoer develpoer;
    
    	public Develpoer getDevelpoer() {
    		return develpoer;
    	}
    	public void setDevelpoer(Develpoer develpoer) {
    		this.develpoer = develpoer;
    	}
    	
    }

pojo：Develpoer

package org.test.submit.bean;
    
    public class Develpoer {
    	private String userId;
    	private String userName;
    	private String realName;
    	
    	public String getUserId() {
    		return userId;
    	}
    	public void setUserId(String userId) {
    		this.userId = userId;
    	}
    	public String getUserName() {
    		return userName;
    	}
    	public void setUserName(String userName) {
    		this.userName = userName;
    	}
    	public String getRealName() {
    		return realName;
    	}
    	public void setRealName(String realName) {
    		this.realName = realName;
    	}
    }

SubmitDao

package org.test.submit.dao;
    
    import org.test.submit.bean.Develpoer;
    
    public interface SubmitDao {
    	public String addDeveloper(Develpoer develpoer);
    }

SubmitDaoImpl

package org.test.submit.dao.impl;
    
    import org.base.MyHibernateDao;
    import org.test.submit.bean.Develpoer;
    import org.test.submit.dao.SubmitDao;
    
    public class SubmitDaoImpl extends MyHibernateDao implements SubmitDao{
    
    	public String addDeveloper(Develpoer develpoer) {
    //		String userId,String userName,String realName
    		String res="fail";
    		if(develpoer==null){
    			
    		}else if(develpoer.getUserId()==null||develpoer.getUserId().trim().equals("")){
    			res="fail";
    		}else{
    			String uname=(develpoer.getUserName()==null)?"":develpoer.getUserName().trim();
    			String rname=(develpoer.getRealName()==null)?"":develpoer.getRealName().trim();
    			String sql="insert into lsy_user_develop(USER_ID, USER_NAME, REAL_NAME) " +
    					" values('"+develpoer.getUserId().trim()+"','"+uname+"','"+rname+"')";
    			this.executeSql(sql);
    			res="success";
    		}
    		
    		return res;
    	}
    
    }

struts\_submit.xml

<?xml version="1.0" encoding="UTF-8" ?>
    <!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"
    "http://struts.apache.org/dtds/struts-2.0.dtd">
    <struts>
    	<package name="submit" extends="base-struts-default" namespace="/submit">
    	    	
    		<action name="addDeveloper" class="org.test.submit.action.IsRepeatSubmitAction">
    		   <result name="success">/jsp/test/repeat.jsp</result>
    		</action>
    		<action name="goSubmit" class="org.test.submit.action.IsRepeatSubmitAction" method="goSubmit">
    		</action>
    	</package>
    </struts>

context\_submit.xml

<?xml version="1.0" encoding="UTF-8"?>
    <beans xmlns="http://www.springframework.org/schema/beans"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xmlns:aop="http://www.springframework.org/schema/aop"
        xmlns:tx="http://www.springframework.org/schema/tx"
        xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.0.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd">
    
        <bean id="submitDaoTarget" class="org.test.submit.dao.impl.SubmitDaoImpl">
    		<property name="sessionFactory">
    			<ref bean="sessionFactory"/>
    		</property>
    	</bean>
    	<bean id="submitDao" parent="transactionProxyTemplate">
    		<property name="target" ref="submitDaoTarget" />
    		<property name="proxyInterfaces">
    			<value>org.test.submit.dao.SubmitDao</value>
    		</property>
    	</bean>
    </beans>

页面;

repeat.jsp

<%@ page contentType="text/html; charset=UTF-8"%>
    <%@page import="java.util.*"%>
    <% 
    String path = request.getContextPath();
    %>
    <% 
    String pk_userId="";
    if(request.getAttribute("userId")!=null){
    	pk_userId=(String)request.getAttribute("userId");
    }
    %>
    <html>
    <head>
    	<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
    	<title></title>
    	<script src="<%=path%>/script/jquery-1.7.1.min.js" type="text/javascript"></script>	
    <style type="text/css"> 
    td,th { 
    font-family: 宋体, Arial; 
    font-size: 12px; 
    }
    
    th { 
    font: bold 11px "Trebuchet MS", Verdana, Arial, Helvetica, sans-serif; 
    color: #4f6b72; 
    border-right: 1px solid #C1DAD7; 
    border-bottom: 1px solid #C1DAD7; 
    border-top: 1px solid #C1DAD7; 
    letter-spacing: 2px; 
    text-transform: uppercase; 
    text-align: left; 
    padding: 6px 6px 6px 12px; 
    background: #CAE8EA  no-repeat; 
    } 
    
    
    
    td { 
    border-right: 1px solid #C1DAD7; 
    border-bottom: 1px solid #C1DAD7; 
    background: #ECFFFF; 
    font-size:11px; 
    padding: 6px 6px 6px 12px; 
    color: #4f6b72; 
    } 
    
    td.other { 
    border-right: 1px solid #C1DAD7; 
    border-bottom: 1px solid #C1DAD7; 
    background: #FFFFDF; 
    font-size:11px; 
    padding: 6px 6px 6px 12px; 
    color: #4f6b72; 
    }
    </style> 
    </head>
    <body style="overflow: scroll; overflow: auto;">
    <input type="hidden" name="path" id="path" value='<%=path%>' ></input>
    
    <form id="form1" action="<%=path%>/submit/goSubmit.action" method="GET">
    <input type="hidden" id="" name="develpoer.userId" value="<%=pk_userId%>"></input>
    
    <table id="table1" cellspacing="0" style="width:700px; padding: 0; margin: 0;">
    	<tr> 
    	  <th>账号</th> 
    	  <th>昵称</th> 
    	</tr>
    
    	<tr> 
    	  <td><input type="text" id="" name="develpoer.userName"></input></td> 
    	  <td><input type="text" id="" name="develpoer.realName"></input></td>
    	</tr> 
    
    	<tr>
    	  <td class="other" colspan="1"><input type="button" value="提交" οnclick="goSubmit()"></input></td>
    	  <td class="other" colspan="1"><input type="button" value="取消" οnclick="clear()"></input></td>
    	</tr>
    </table>
    </form>
    
    </body>
    </html> 
    <script type="text/javascript">	
    
    function goSubmit(){
    	document.all.form1.submit();
    	
    }
    
    function clear(){
    	$("input['name=develpoer.userName']").val("");
    	$("input['name=develpoer.realName']").val("");
    }
    
    </script>

实验：在页面填入数据，点击提交按钮，打印：

主键userId：f6463fb03dbae37b013dbae37b680000  
Hibernate: insert into lsy\_user\_develop(USER\_ID, USER\_NAME, REAL\_NAME)  values('f6463fb03dbae37b013dbae37b680000','55','555')  
成功写库！Sat Mar 30 18:42:50 CST 2013

成功提交后，按F5刷新页面：

打印：  
主键userId：f6463fb03dbae37b013dbae37b680000  
您已提交过表单！

或者点击浏览器的回退按钮回到刚才的页面，再点击提交。打印：  
主键userId：f6463fb03dbae37b013dbae37b680000  
您已提交过表单！

好，从结果上看，这个思路是可行的！

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从网上搜了一下，struts2有个防止表单重复提交的标签<s: token />，配合拦截器 <interceptor-ref name="token" />来使用。

大体是：

在页面加载时，<s: token />产生一个GUID（Globally Unique Identifier，全局唯一标识符）值的隐藏输入框  
同时，将GUID放到会话（session）中；在执行action之前，“token”拦截器将会话token与请求token比较，如果两者相同，则将会话中的token删除并往下执行，否则向actionErrors加入错误信息。如此一来，如果用户通过某种手段提交了两次相同的请求，两个token就会不同。

\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#\#

我想这个原理和我想到的解决方案大同小异。只不过struts2把这个写入了标签库和拦截器中。

具体逻辑上strus2根据session是否有这个唯一标识来判断，我根据这个标识的提交次数来判断的。

从实施上，我们完全不必要使用struts2的方案，因为我不喜欢struts2的标签库。只要懂了原理，自己照样能实现。