今天刚学了用struts2的拦截器,就用他做了个权限控制的小例子来加深对拦截器的认识.用户经合法途径登陆后用户登陆信息会保存在session中,用户在访问其他资源时,拦截器会首先查看session中是否有用户信息.从而控制用户登陆
login.jsp系统登录页
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>
<body>
<s:form name="form1" action="login">
<s:textfield name="username" label="username"></s:textfield>
<s:password name="password" label="password"></s:password>
<s:submit value="submit"/>
</s:form>
</body>
</html>
package com.huan.tv.web;
import com.huan.tv.domain.User;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;
public class LoginAction extends ActionSupport {
private static final long serialVersionUID = 7016663291573110941L;
private String username;
private String password;
@Override
public String execute() throws Exception {
if("java".equals(username.trim())&&"123".equals(password.trim())){
User user = new User(username,password);
ActionContext.getContext().getSession().put("user", user);
}
return SUCCESS;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
Uer.java类封装了用户登陆的信息
package com.huan.tv.domain;
public class User {
private String username;
private String password;
public User() {
super();
}
public User(String username, String password) {
super();
this.username = username;
this.password = password;
}
public String getUsername() {
return username;
}
public void setUsername(String username) {
this.username = username;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
}
下面就是关键的拦截器了
package com.huan.tv.web;
import javax.servlet.http.HttpServletResponse;
import org.apache.struts2.ServletActionContext;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;
public class AuthorInterceptor extends AbstractInterceptor {
private static final long serialVersionUID = 5359767511938232965L;
public String intercept(ActionInvocation invocation) throws Exception {
ActionContext ac = ActionContext.getContext();
Object user = ac.getSession().get("user");
if (user != null) {
return invocation.invoke();
} else {
HttpServletResponse response = ServletActionContext.getResponse();
response.setContentType("text/html;charset=UTF-8");
response.getWriter().write(
"<script language=\"javascript\">alert('请登录系统！');parent.location.href='"
+ ServletActionContext.getRequest()
.getContextPath() + "/login.jsp';</script>");
}
return null;
}
}
拦截器就是通过判断session里user是否有值,user为空说明用户没有登陆就返回首页.登陆后就invocation.invoke();将控制权转交给Action的execute方法
配置文件struts.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="base-package" extends="struts-default">
<interceptors>
<interceptor name="author"
class="com.huan.tv.web.AuthorInterceptor" />
<interceptor-stack name="permissionStack">
<interceptor-ref name="defaultStack" />
<interceptor-ref name="author" />
</interceptor-stack>
</interceptors>
<action name="login" class="com.huan.tv.web.LoginAction">
<result>/welcome.jsp</result>
</action>
<action name="view" class="com.huan.tv.web.ViewAction">
<result>/index.jsp</result>
<interceptor-ref name="permissionStack"/>
</action>
</package>
</struts>
我们定义了一个拦截器栈,它包含刚写了权限拦截器和默认拦截器.login是登陆的不用权限控制.view是登陆后查看的需要加上拦截器.如果用户不登陆直接访问view.action则系统拦截器就会起作用,提示用户登陆后才能操作.
welcome.jsp登陆后的欢迎页
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@ taglib prefix="s" uri="/struts-tags" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>
<body>
登陆成功! <br>
<s:form action="view">
<s:submit value="submit"/>
</s:form>
</body>
</html>
index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>
<body>
经过view.action后访问的 <br>
</body>
</html>
最后别忘了web.xml中添加struts2
<filter>
<filter-name>Struts2</filter-name>
<filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>Struts2</filter-name>
<url-pattern>*.action</url-pattern>
</filter-mapping>
<filter-mapping>
<filter-name>Struts2</filter-name>
<url-pattern>*.jsp</url-pattern>
</filter-mapping>
