JSP使用自定义标签防止表单重复提交的方法

2020-07-27 21:30:43

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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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