struts2中的拦截器

最新推荐文章于 2024-09-04 11:52:54 发布

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#浏览器 #Struts #JSP #XML #Apache

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一.理解拦截器

1. 拦截器是在防问某个方法，字段之前或之后实施拦截，并且拦截器是可插拔的，拦截器是ＡＯＰ的一种实现．

2. 拦截器栈（Interceptor Stack）。拦截器栈就是将拦截器按一定的顺序联结成一条链。在访问被拦截的方法或字段时，拦截器链中的拦截器就会按其之前定义的顺序被调用。

二.实现原理
Struts2拦截器的实现原理相对简单，当请求struts2的action时，Struts 2会查找配置文件，并根据其配置实例化相对的拦截器对象，然后串成一个列表，最后一个一个地调用列表中的拦截器

三.拦截器的配置
1. 普通的拦截器

Xml代码

<package name="default" extends="struts-default"> 
<interceptors> 
<interceptor name="拦截器名1" class="拦截器实现类"/> 
<interceptor name="拦截器名2" class="拦截器实现类"/> 
</interceptors> 
<action name="login"　class="com.Logon"> 
<interceptor-ref name="defaultStack"/> 
<interceptor-ref name="拦截器名1"/> 
<interceptor-ref name="拦截器名2"/> 
<result name="input">logon.jsp</result>
<result name="success">/index.jsp</result>
</action> 
</package>

<package name="default" extends="struts-default">



   <interceptors>



       <interceptor name="拦截器名1" class="拦截器实现类"/>



       <interceptor name="拦截器名2" class="拦截器实现类"/>



   </interceptors>



<action name="login"　class="com.Logon">



　　<interceptor-ref name="defaultStack"/>



        <interceptor-ref name="拦截器名1"/>



        <interceptor-ref name="拦截器名2"/>



         <result name="input">logon.jsp</result>



         <result name="success">/index.jsp</result>



   </action>



</package>

2. 拦截器栈

Xml代码

<package name="default" extends="struts-default"> 
<interceptors> 
<interceptor name="拦截器名1" class="拦截器实现类"/> 
<interceptor name="拦截器名2" class="拦截器实现类"/> 
<interceptor-stack name="myStack"> 
<interceptor-ref name="拦截器名1"/> 
<interceptor-ref name="拦截器名2"/> 
</interceptor-stack> 
</interceptors> 
<action name="login" class="com.Logon"> 
<interceptor-ref name="defaultStack"/> 
<interceptor-ref name="myStack"/> 
<result name="input">login.jsp</result>
<resultnameresultname="success" >/index.jsp</result>
</action> 
</package>

<package name="default" extends="struts-default">



   <interceptors>



        <interceptor name="拦截器名1" class="拦截器实现类"/>



        <interceptor name="拦截器名2" class="拦截器实现类"/>



        <interceptor-stack name="myStack">



           <interceptor-ref name="拦截器名1"/>



           <interceptor-ref name="拦截器名2"/>



        </interceptor-stack>



    </interceptors>



    <action name="login" class="com.Logon">



　　　　　<interceptor-ref name="defaultStack"/>



         <interceptor-ref name="myStack"/>



         <result name="input">login.jsp</result>



         <resultname="success" >/index.jsp</result>



</action>



</package>

需要注意的是，如果为Action指定了一个拦截器，则系统默认的拦截器栈将会失去作用。为了继续使用默认拦截器，所以上面配置文件中手动引入了默认拦截器

四.自定义拦截器
 1.直接或间接实现接口com.opensymphony.xwork2.interceptor.Interceptor。
 2.或者继承类com.opensymphony.xwork2.interceptor.AbstractInterceptor
 3.通过<interceptor>元素来定义拦截器
 4.通过<interceptor-ref>元素来使用拦截器

五.使用拦截器实现权限控制
1.功能
使用自定义拦截器来完成用户权限的控制，当执行操作时，判断用户是否己经登陆，如果没有登陆跳转到登陆页面

2.拦截器类

Java代码

package com.interceptor;
import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;
public class AuthorizationInterceptor extends AbstractInterceptor {
private static final long serialVersionUID = 1L;
@Override
public String intercept(ActionInvocation actionInvocation) throws Exception {
ActionContext actionContext = actionInvocation.getInvocationContext();
Object user = actionContext.get("user");
if(user != null){
return actionInvocation.invoke();
} else{
actionInvocation.getInvocationContext().put("nav_title", "你还没有登陆,请先登陆");
return Action.LOGIN;
}
}
}

package com.interceptor;



import com.opensymphony.xwork2.Action;

import com.opensymphony.xwork2.ActionContext;

import com.opensymphony.xwork2.ActionInvocation;

import com.opensymphony.xwork2.interceptor.AbstractInterceptor;



public class AuthorizationInterceptor extends AbstractInterceptor {



	private static final long serialVersionUID = 1L;



	@Override

	public String intercept(ActionInvocation actionInvocation) throws Exception {

		

		ActionContext actionContext = actionInvocation.getInvocationContext();

		

		Object user = actionContext.get("user");

		

		if(user != null){

			return actionInvocation.invoke();

		} else{

			actionInvocation.getInvocationContext().put("nav_title", "你还没有登陆,请先登陆");

			return Action.LOGIN;

		}

	}



}

2.配置

Xml代码

<?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="user" extends="struts-default">
<interceptors>
<interceptor name="authority" class="com.interceptor.AuthorizationInterceptor"></interceptor>
</interceptors> 
<action name="user" class="com.UserAction"> 
<interceptor-ref name="authority"/>
<interceptor-ref name="defaultStack"/>
<result name="succee">/logon/welcome.jsp</result>
<result name="login">/logon/logon.jsp</result>
</action>
</package>
</struts>

<?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="user" extends="struts-default">

    	<interceptors>
    		<!-- 定义拦截器  -->
    		<interceptor name="authority" class="com.interceptor.AuthorizationInterceptor"></interceptor>
    	</interceptors>


        <action name="user" class="com.UserAction">

        	<!-- 使用拦截器 -->
        	<interceptor-ref name="authority"/>
        	<interceptor-ref name="defaultStack"/>
            <result name="succee">/logon/welcome.jsp</result>

            <result name="login">/logon/logon.jsp</result>
        </action>
    </package>
</struts>

访问http://localhost:8080/struts2-interceptor/user.action时，会判断用户是否登陆

六.方法拦截器
1.Struts2提供MethodFilterInterceptor类，该类是AbstractInerceptor的子类，可以实现对Action方法的拦截.
2. MethodFilterInterceptor中有两个方法
　 setExcludeMethods:排除需要过滤的方法
setIncludeMethods:设置需要过滤的方法
如果一个方法同时在excludeMethods和includeMethods中出现,则会被拦截

3.实现

拦截器

Java代码

package com.interceptor;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;
public class LogInterceptor extends MethodFilterInterceptor {
private static final long serialVersionUID = 1L;
private String name;
@Override
protected String doIntercept(ActionInvocation actionInvocation) throws Exception {
System.out.println("拦截器名称:" + name);
System.out.println("action:" + actionInvocation.getAction());
return actionInvocation.invoke();
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
}

package com.interceptor;



import com.opensymphony.xwork2.ActionInvocation;

import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;



public class LogInterceptor extends MethodFilterInterceptor {



	private static final long serialVersionUID = 1L;



	private String name;

	

	@Override

	protected String doIntercept(ActionInvocation actionInvocation) throws Exception {

	

		System.out.println("拦截器名称:" + name);

		System.out.println("action:" + actionInvocation.getAction());

		

		return actionInvocation.invoke();

	}



	public String getName() {

		return name;

	}



	public void setName(String name) {

		this.name = name;

	}

}

action

Java代码

package com;
public class ManageAction {
public String execute(){
System.out.println("execute....");
return "succee";
}
public String search(){
System.out.println("search....");
return "succee";
}
public String add(){
System.out.println("add....");
return "succee";
}
}

package com;


public class ManageAction {


	public String execute(){
		System.out.println("execute....");

		return "succee";
	}


	public String search(){

		System.out.println("search....");
		return "succee";
	}
	public String add(){
		System.out.println("add....");
		return "succee";
	}
}

struts.xml配置

Xml代码

<action name="manage" class="com.ManageAction"> 
<interceptor-ref name="log"> 
<param name="name">日志拦截</param> 
<param name="includeMethods">execute,add</param>
 
<param name="excludeMethods">search,execute</param>
</interceptor-ref> 
<result name="succee">/welcome.jsp</result>
</action>

<action name="manage" class="com.ManageAction">

         	<interceptor-ref name="log">

         		<param name="name">日志拦截</param>

         		<!-- 设置需要拦截的方法,指定多个方法以逗号隔开 -->

         		<param name="includeMethods">execute,add</param>

         		<!-- 设置不需要拦截的方法,execute在includeMethods中同时存在，execute会被拦截 -->

         		<param name="excludeMethods">search,execute</param>
         	</interceptor-ref>

         	<result name="succee">/welcome.jsp</result>
         </action>

打开浏览器访问　http://localhost:8080/struts2-interceptor/manage.action

会报执行execute方法，会执行拦截器
拦截器名称:日志拦截
action:com.ManageAction@1a0ae6d
execute....

当访问 http://localhost:8080/struts2-interceptor/manage!search.action
执行search方法，不会执行拦截器