07-拦截器

1 拦截器的创建

1 方式1-实现 Interceptor

package www.test.a_interceptor;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.Interceptor;

//拦截器:第一种创建方式
//拦截器生命周期:随项目的启动而创建,随项目关闭而销毁
public class MyInterceptor implements Interceptor{

    
    @Override
    //初始化方法
    public void init() {
    }

    @Override
    //拦截方法
    public String intercept(ActionInvocation arg0) throws Exception {
        
        return null;
    }
    @Override
    //销毁方法
    public void destroy() {
    }


}

2 方式 2-继承 AbstractInterceptor

package www.test.a_interceptor;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;

//创建方式2: 继承AbstractInterceptor -> struts2的体贴
//帮我们空实现了init 和 destory方法. 我们如果不需要实现这两个方法,就可以只实现intercept方法
public class MyInterceptor2 extends AbstractInterceptor {

    @Override
    public String intercept(ActionInvocation arg0) throws Exception {

        return null;
    }

}

3 方式 3-继承 MethodFilterInterceptor

package www.test.a_interceptor;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;

//继承:MethodFilterInterceptor 方法过滤拦截器
//功能: 定制拦截器拦截的方法.
//    定制哪些方法需要拦截.
//    定制哪些方法不需要拦截
public class MyInterceptor3 extends MethodFilterInterceptor {

    @Override
    protected String doIntercept(ActionInvocation invocation) throws Exception {

        //前处理
        System.out.println("MyInterceptor3的前处理");
        //放行
        String result = invocation.invoke();
        //后处理
        System.out.println("MyInterceptor3的后处理");
        
        return result;
    }

}

2 拦截器的配置

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE struts PUBLIC
    "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"
    "http://struts.apache.org/dtds/struts-2.3.dtd">
<struts>
    <constant name="struts.devMode" value="true"></constant>
    <package name="interceptor" namespace="/" extends="struts-default">
        <interceptors>
            <!--1 注册拦截器  -->
            <interceptor name="myInterceptor3" class="www.test.a_interceptor.MyInterceptor3"></interceptor>
            <!--2 注册拦截器栈  -->
            <interceptor-stack name="myStack">
                <!--引入自定义的拦截器（建议放在20个默认拦截器之前）  -->
                <interceptor-ref name="myInterceptor3">
                    <!--指定哪些方法不需要拦截  -->
                    <!-- <param name="excludeMethods">add,find</param> -->
                    <!--指定哪些方法需要拦截  -->  
                    <param name="includeMethods">find,add</param>
                </interceptor-ref>
                <!--引用默认的拦截器（20个）  -->
                <interceptor-ref name="defaultStack"></interceptor-ref>
            </interceptor-stack>
        </interceptors>
        <!--3指定包中的默认拦截器栈 -->
        <default-interceptor-ref name="myStack"></default-interceptor-ref>
        <action name="Demo1Action_*" class="www.test.a_interceptor.Demo1Action" method="{1}">
            <!--为Action单独指定走那个拦截器栈  -->
            <!-- <interceptor-ref name="myStack"></interceptor-ref> -->
            <result name="success" type="dispatcher">/index.jsp</result>
        </action>
    </package>
</struts>

3 其它

1 Demo1Action

package www.test.a_interceptor;

import com.opensymphony.xwork2.ActionSupport;

public class Demo1Action extends ActionSupport {

    public String add() throws Exception {
        System.out.println("Demo1Action_add!");
        return SUCCESS;
    }
    
    public String delete() throws Exception {
        System.out.println("Demo1Action_delete!");
        return SUCCESS;
    }
    
    public String update() throws Exception {
        System.out.println("Demo1Action_update!");
        return SUCCESS;
    }
    
    public String find() throws Exception {
        System.out.println("Demo1Action_find!");
        return SUCCESS;
    }
}

2 拦截器api

MyInterceptor3中如果使用return "success"; 那么执行了MyInterceptor3这个拦截器之后就不会在执行下面的20个默认拦截器了。