struts拦截器的使用

做一个简单的例子，用户只有在成功登录之后，进行添加教师信息，然后在返回到当前界面，主要用到了拦截器，防止用户未登录时直接访问添加教师信息这个界面。由于例子很小就不访问数据库了。struts的配置在之前也提到过了在这里也不重复了

拦截器作用：拦截器是动态拦截Action调用的对象。它提供了一种机制可以使开发者可以定义在一个action执行的前后执行的代码，也可以在一个action执行前阻止其执行。同时也是提供了一种可以提取action中可重用的部分的方式。

自定义拦截器：

①建一个类实现接口Interceptor

②实现接口的intercept（）方法

③在struts.xml中的<package>元素中加入拦截器，

④需要注意的是，若想使用拦截器必须将这个拦截器放到相应的action中，但是这又出现一个问题，如果为当前action设置了一个拦截器，那么其原来默认的所以拦截器都会失效，因此需要用到了拦截器栈的概念。

⑤

<interceptors><interceptor name="seinpt" class="com.inpt.SessionInterceptor"></interceptor><interceptor-stack name="sysinpt"><interceptor-ref name="defaultStack"></interceptor-ref><interceptor-ref name="seinpt"></interceptor-ref></interceptor-stack></interceptors>

⑥在<package>中<default-interceptor-ref name="sysinpt"></default-interceptor-ref>。他自己会自动调用你设计的拦截器 并且保留默认的一些拦截器。

 

下面是完整的这个小例子的包以及文件截图

一、com.action

①LoginAction.java 用户登录验证若账号等于sdd密码等于sdd那么登录成功，session中存入当前user

package com.action;import com.bean.User;import com.opensymphony.xwork2.ActionContext;public class LoginAction {private User u;public User getU() {return u;}public void setU(User u) {this.u = u;}public String login(){System.out.println(u);if(u.getLogname().equals("sdd")&&u.getPassword().equals("sdd")){ActionContext.getContext().getSession().put("user",u);System.out.println("登录成功");return "success";}return "unsuccess";}}

②TeacherAction.java

package com.action;import com.bean.Teacher;public class TeacherAction {private Teacher t;public Teacher getT() {return t;}public void setT(Teacher t) {this.t = t;}public String addInfo(){System.out.println(t.getTname());System.out.println(t.getTage());return "success";}public String deleteInfo(){return "success";}public String updateInfo(){return "success";}}

 

二、com.bean

①Teacher.java

package com.bean;public class Teacher {private String tname;private int tage;public String getTname() {return tname;}public void setTname(String tname) {this.tname = tname;}public int getTage() {return tage;}public void setTage(int tage) {this.tage = tage;}public Teacher(String tname, int tage) {super();this.tname = tname;this.tage = tage;}public Teacher() {// TODO Auto-generated constructor stub}}

 

②User.java

package com.bean;public class User {private String logname;private String password;public String getLogname() {return logname;}public void setLogname(String logname) {this.logname = logname;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public User(String logname, String password) {super();this.logname = logname;this.password = password;}public User() {// TODO Auto-generated constructor stub}}

 

三、com.inpt

①SessionInterceptor.java  拦截器动态拦截Action方法调用的对象

package com.inpt;import com.action.LoginAction;import com.opensymphony.xwork2.ActionContext;import com.opensymphony.xwork2.ActionInvocation;import com.opensymphony.xwork2.interceptor.Interceptor;public class SessionInterceptor  implements Interceptor{public void destroy() {// TODO Auto-generated method stub}public void init() {System.out.println("拦截器初始化=======");}public String intercept(ActionInvocation arg0) throws Exception {if(!arg0.getAction().getClass().equals(LoginAction.class)){ActionContext act=ActionContext.getContext();if(act.getSession().get("user")==null){return "unsuccess";}}return arg0.invoke();}}

 

四、struts.xml

<interceptor name="seinpt" class="com.inpt.SessionInterceptor"></interceptor>设置一个拦截器，名称为seinpt

 

<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.1//EN" "http://struts.apache.org/dtds/struts-2.1.dtd"><struts><package name="sys" extends="struts-default" namespace="" abstract="true"><global-results><result name="success">/welcome.jsp</result><result name="unsuccess">/index.jsp</result></global-results></package><package name="app" extends="sys" namespace="/sysjsp"><interceptors><interceptor name="seinpt" class="com.inpt.SessionInterceptor"></interceptor><interceptor-stack name="sysinpt"><interceptor-ref name="defaultStack"></interceptor-ref><interceptor-ref name="seinpt"></interceptor-ref></interceptor-stack></interceptors><default-interceptor-ref name="sysinpt"></default-interceptor-ref><action name="logac_*" class="com.action.LoginAction" method="{1}"></action>    <action name="teacher_*" class="com.action.TeacherAction" method="{1}">    </action></package></struts>    

 

五、jsp界面

①index.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>My JSP 'index.jsp' starting page</title><meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0">    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">-->  </head>    <body>   <form action="sysjsp/logac_login" method="post">   账号：<input type="text" name="u.logname"><br/>   密码：<input type="text" name="u.password"><br/>   <input type="submit"><br/>   </form>  </body></html>

 

②welcome.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html>  <head>    <base href="<%=basePath%>">        <title>My JSP 'welcome.jsp' starting page</title>    <meta http-equiv="pragma" content="no-cache"><meta http-equiv="cache-control" content="no-cache"><meta http-equiv="expires" content="0">    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"><meta http-equiv="description" content="This is my page"><!--<link rel="stylesheet" type="text/css" href="styles.css">-->  </head>    <body>  您好：${u.logname}  <br/>  <form action="sysjsp/teacher_addInfo" method="post">  教师姓名：<input type="text" name="t.tname"><br/>   教师年龄：<input type="text" name="t.tage"><br/>    <input type="submit"><br/>  </form>  </body></html>