struts2中的拦截器

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

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


    <interceptors><BR>


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


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


    </interceptors><BR>


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


 　　<interceptor-ref name="defaultStack"/><BR>


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


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


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


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


    </action><BR>


 </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

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


    <interceptors><BR>


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


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


         <interceptor-stack name="myStack"><BR>


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


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


         </interceptor-stack><BR>


     </interceptors><BR>


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


 　　　　　<interceptor-ref name="defaultStack"/><BR>


          <interceptor-ref name="myStack"/><BR>


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


          <resultnameresultname="success" >/index.jsp</result><BR>


 </action><BR>


 </package><BR>

<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

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

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 version="1.0" encoding="UTF-8" ?><BR>


 <!DOCTYPE struts PUBLIC<BR>


     "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN"<BR>


     "http://struts.apache.org/dtds/struts-2.0.dtd"><BR>

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

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

         <action name="user" class="com.UserAction"><BR>
             <!-- 使用拦截器 -->
             <interceptor-ref name="authority"/>
             <interceptor-ref name="defaultStack"/>
             <result name="succee">/logon/welcome.jsp</result><BR>
             <result name="login">/logon/logon.jsp</result>
         </action>
     </package>
 </struts><BR>

<?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

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

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

package com;<BR><BR>
 public class ManageAction {<BR><BR>
     public String execute(){
         System.out.println("execute....");<BR>
         return "succee";
    }<BR>

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

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

<action name="manage" class="com.ManageAction"><BR>
             <interceptor-ref name="log"><BR>
                 <param name="name">日志拦截</param><BR>
                 <!-- 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><BR>
                 <!-- 设置不需要拦截的方法,execute在includeMethods中同时存在，execute会被拦截 --><BR>
                 <param name="excludeMethods">search,execute</param>
             </interceptor-ref><BR>
             <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