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JSP使用自定义标签防止表单重复提交的方法

程序员文章站 2022-08-10 18:45:09
本文实例讲述了jsp使用自定义标签防止表单重复提交的方法。分享给大家供大家参考。具体如下： 1. 编写servelt： package cn.itcast.ap...

本文实例讲述了jsp使用自定义标签防止表单重复提交的方法。分享给大家供大家参考。具体如下：

1. 编写servelt：

package cn.itcast.apsliyuan.web.servlet;
import java.io.ioexception;
import javax.servlet.servletexception;
import javax.servlet.http.httpservlet;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
public class loginservet extends httpservlet {
  /**
   * 反序列化
   */
  private static final long serialversionuid = 4960707156159691747l;
  @override
  public void dopost(httpservletrequest requset,
      httpservletresponse response) throws servletexception, ioexception {
    // 获得输入框中的值
    string token = requset.getparameter("tokenname");
    // 获得session中的值
    string sessiontoken = (string) requset.getsession().getattribute(
        "token");
    if (token.equals(sessiontoken)) {
      response.getwriter().print("保存成功");
      requset.getsession().removeattribute("token");//为了保证session中的值不重复，所以移除
    } else {
      response.getwriter().print("对不起不能重复提交");
    }
  }
}

2. 编写自定义标签的类：

package cn.itcast.apsliyuan.tag;
import java.io.ioexception;
import java.util.uuid;
import javax.servlet.jsp.jspexception;
import javax.servlet.jsp.tagext.tagsupport;
public class logintokentag extends tagsupport{
  /**
   * 凡序列化
   */
  private static final long serialversionuid = -1815168785364991254l;
  @override
  public int dostarttag() throws jspexception {
    // todo auto-generated method stub
    //得到uuid
    string uuid=uuid.randomuuid().tostring().replace("-","");
    //得到session,pagecontext 是域对象同样也是工具类
    pagecontext.getsession().setattribute("token",uuid);
    string html="<input type='text' name='tokenname' readonly='readonly' value="+uuid+">";
    try {
      pagecontext.getout().print(html);
    } catch (ioexception e) {
      // todo auto-generated catch block
      e.printstacktrace();
    }
    return eval_body_include;
  }
}

3. 编写×.tld文件：

<?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">
  <!-- 定义版本 -->
  <tlib-version>1.0</tlib-version>
  <!-- 定义名字 -->
  <short-name>apsliyuan</short-name>
  <!-- 定义uri -->
  <uri>http://my.oschina.net/aps</uri>
  <tag>
    <name>logintokentag</name>
    <tag-class>cn.itcast.apsliyuan.tag.logintokentag</tag-class>
    <body-content>jsp</body-content>
  </tag>
</taglib>

4. jsp中的代码：

<%@ page language="java" contenttype="text/html; charset=utf-8"
  pageencoding="utf-8"%>
  <%@taglib uri="http://my.oschina.net/aps" prefix="aps" %>
  <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<!doctype html public "-//w3c//dtd html 4.01 transitional//en" "http://www.w3.org/tr/html4/loose.dtd">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<title>index.jsp</title>
</head>
<body>
  <form action="${pagecontext.request.contextpath}/server/login" method="post">
    <aps:logintokentag/>
    <input type="submit" value="login"/>
  </form>
</body>
</html>

5. 防止乱码的拦截器：

package cn.itcast.apsliyuan.filter;
import java.io.ioexception;
import javax.servlet.filter;
import javax.servlet.filterchain;
import javax.servlet.filterconfig;
import javax.servlet.servletexception;
import javax.servlet.servletrequest;
import javax.servlet.servletresponse;
import javax.servlet.http.httpservletrequest;
import javax.servlet.http.httpservletresponse;
public class uncodefilter implements filter {
  public void init(filterconfig filterconfig) throws servletexception {
    // todo auto-generated method stub
    system.out.println("拦截完成");
  }
  public void dofilter(servletrequest req, servletresponse res,
      filterchain chain) throws ioexception, servletexception {
      httpservletrequest request=(httpservletrequest) req;
      httpservletresponse response=(httpservletresponse) res;
      request.setcharacterencoding("utf-8");
      response.setcontenttype("text/html;charset=utf-8");
      chain.dofilter(request, response);
  }
  public void destroy() {
    // todo auto-generated method stub
  }
}

6. web.xml中的配置：

<?xml version="1.0" encoding="utf-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/xmlschema-instance"
  xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
  xsi:schemalocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
  id="webapp_id" version="2.5">
  <display-name>tag</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <servlet>
    <servlet-name>loginservlet</servlet-name>
    <servlet-class>cn.itcast.apsliyuan.web.servlet.loginservet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>loginservlet</servlet-name>
    <url-pattern>/server/login</url-pattern>
  </servlet-mapping>
  <filter>
    <filter-name>uncodefilter</filter-name>
    <filter-class>cn.itcast.apsliyuan.filter.uncodefilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>uncodefilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
</web-app>

希望本文所述对大家的jsp程序设计有所帮助。

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