拦截器是Struts2的基础,什么是拦截器呢?(二)
packagetutorial;
importcom.opensymphony.xwork2.ActionSupport;
publicclassAuthorizatedAccessextendsActionSupportimplementsRoleAware{
privateStringrole;
publicvoidsetRole(Stringrole){
this.role=role;
}
publicStringgetRole(){
returnrole;
}
@Override
publicStringexecute(){
returnSUCCESS;
}
}
以下是ShowUser.jsp的代码：
<%@pagecontentType="text/html;charset=UTF-8"%>
<%@taglibprefix="s"uri="/struts-tags"%>
<html>
<head>
<title>AuthorizatedUser</title>
</head>
<body>
<h1>Yourroleis:<s:propertyvalue="role"/></h1>
</body>
</html>
然后，创建tutorial.Roles初始化角色列表，代码如下：
packagetutorial;
importjava.util.Hashtable;
importjava.util.Map;
publicclassRoles{
publicMap<String,String>getRoles(){
Map<String,String>roles=newHashtable<String,String>(2);
roles.put("EMPLOYEE","Employee");
roles.put("MANAGER","Manager");
returnroles;
}
}
接下来，新建Login.jsp实例化tutorial.Roles，并将其roles属性赋予<s:radio>标志，代码如下：
<%@pagecontentType="text/html;charset=UTF-8"%>
<%@taglibprefix="s"uri="/struts-tags"%>
<html>
<head>
<title>Login</title>
</head>
<body>
<h1>Login</h1>
Pleaseselectarolebelow:
<s:beanid="roles"name="tutorial.Roles"/>
<s:formaction="Login">
<s:radiolist="#roles.roles"value="'EMPLOYEE'"name="role"label="Role"/>
<s:submit/>
</s:form>
</body>
</html>
创建Action类tutorial.Login将role放到session中，并转到Action类tutorial.AuthorizatedAccess，代码如下：
packagetutorial;
importjava.util.Map;
importorg.apache.struts2.interceptor.SessionAware;
importcom.opensymphony.xwork2.ActionSupport;
publicclassLoginextendsActionSupportimplementsSessionAware{
privateStringrole;
privateMapsession;
publicStringgetRole(){
returnrole;
}
publicvoidsetRole(Stringrole){
this.role=role;
}
publicvoidsetSession(Mapsession){
this.session=session;
}
@Override
publicStringexecute(){
session.put("ROLE",role);
returnSUCCESS;
}
}
最后，配置struts.xml文件，内容如下：
<!DOCTYPEstrutsPUBLIC
"-//ApacheSoftwareFoundation//DTDStrutsConfiguration2.0//EN"
"http://struts.apache.org/dtds/struts-2.0.dtd">
<struts>
<includefile="struts-default.xml"/>
<packagename="InterceptorDemo"extends="struts-default">
<interceptors>
<interceptorname="auth"class="tutorial.AuthorizationInterceptor"/>
</interceptors>
<actionname="Timer"class="tutorial.TimerInterceptorAction">
<interceptor-refname="timer"/>
<result>/Timer.jsp</result>
</action>
<actionname="Login"class="tutorial.Login">
<resulttype="chain">AuthorizatedAccess</result>
</action>
<actionname="AuthorizatedAccess"class="tutorial.AuthorizatedAccess">
<interceptor-refname="auth"/>
<resultname="login">/Login.jsp</result>
<resultname="success">/ShowRole.jsp</result>
</action>
</package>
</struts>
发布运行应用程序，在浏览器地址栏中输入：http://localhost:8080/Struts2_Interceptor/AuthorizatedAccess.action。由于此时，session还没有键为“ROLE”的值，所以返回Login.jsp页面，如图2所示：
图２Login.jsp
选中Employee，点击Submit，出现图3所示页面：
图3ShowRole.jsp
总结
拦截器是Struts2比较重要的一个功能。通过正确地使用拦截器，我们可以编写高可复用的代码
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