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struts2学习札记十一（第11讲.Struts2的核心 拦截器续）

分类: IT文章 • 2022-06-12 09:45:53
struts2学习笔记十一（第11讲.Struts2的核心 拦截器续）
Struts2的核心 拦截器续
说明：拦截器的主要作用就是拦截Action，执行顺序就是：拦截器->Action->拦截器->……。
功能：拦截器的基本的配置。
一、在之前的struts2项目src下创建一个包com.test.interceptor，用来存放拦截器，创建一个名称为MyInterceptor.java类，实现Interceptor接口：
package com.test.interceptor;

import java.awt.event.InvocationEvent;

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

public class MyInterceptor implements Interceptor {

	public void destroy() {
		
		System.out.println("destroy()");
	}

	public void init() {
		
		System.out.println("init()");
	}

	public String intercept(ActionInvocation invocation) throws Exception {
	
		System.out.println("intercept");
		
		String result = invocation.invoke();
		
		return result;
	}
}

二、在struts.xml配置文件中配置拦截器，在package节点先添加interceptors节点，并且要在对应的Action中进行引用：
<?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>
	
	<constant name="struts.custom.i18n.resources" value="message">
	
	</constant>
	
	<package name="struts2" extends="struts-default">
		
		<interceptors>
			<interceptor name="myInterceptor" class="com.test.interceptor.MyInterceptor">
				
			</interceptor>
		</interceptors>
	
		<action name="login" class="com.test.action.LoginAction">
			<result name="input">/login2.jsp</result>
			<result name="success">/result.jsp</result>
			<result name="failer">login2.jsp</result>
		</action>
		
		<action name="pointConverter" class="com.test.action.PointAction">
			<result name="success">/output.jsp</result>
		</action>
		
		<action name="register" class="com.test.action.RegisterAction">
			<result name="success">/success.jsp</result>
			<result name="input">/register2.jsp</result>
			
			<interceptor-ref name="myInterceptor"></interceptor-ref>
			<interceptor-ref name="defaultStack"></interceptor-ref>
			
		</action>
		
		<action name="zly" class="com.test.action.RegisterAction" method="test">
			<result name="success">/success.jsp</result>
			<result name="input">/register2.jsp</result>
		</action>
	</package>
	
</struts>

三、再在struts.xml中的Intercepoters节点中添加一个param参数：
<interceptors>
			<interceptor name="myInterceptor" class="com.test.interceptor.MyInterceptor">
				<param name="hello">world</param>
			</interceptor>
		</interceptors>

四、然后在拦截器MyInterceptor.java中添加一个对应的对象hello：
public void init() {
		
		System.out.println("init()");
		System.out.println(hello);
	}

结果是world能在控制台正常的输出：init()
world
五、然后在Action中引用的时候，在在引用的属性中再增加一个param属性，并且把welcome赋给hello：
	<action name="register" class="com.test.action.RegisterAction">
			<result name="success">/success.jsp</result>
			<result name="input">/register2.jsp</result>
			
			<interceptor-ref name="myInterceptor">
				<param name="hello">welcome</param>
			</interceptor-ref>
			<interceptor-ref name="defaultStack"></interceptor-ref>
			
		</action>

在控制台输出的是：init()
welcome，说明后来所赋得值welcome把前面的给替换掉了，所以说使用的时候给变量赋的值，会替换掉之前定义的时候所赋得值。
功能：定义拦截器栈。
六、还是在Intercepoters借点节点中添加一个拦截器栈，然后在对应的Action中引用这个拦截器栈，效果是一样的：
<package name="struts2" extends="struts-default">
		
		<interceptors>
			<interceptor name="myInterceptor" class="com.test.interceptor.MyInterceptor">
				<param name="hello">world</param>
			</interceptor>
			
			<interceptor-stack name="myStack">
				<interceptor-ref name="myInterceptor"></interceptor-ref>
				<interceptor-ref name="defaultStack"></interceptor-ref>
			</interceptor-stack>
		</interceptors>
	
		<action name="login" class="com.test.action.LoginAction">
			<result name="input">/login2.jsp</result>
			<result name="success">/result.jsp</result>
			<result name="failer">login2.jsp</result>
		</action>
		
		<action name="pointConverter" class="com.test.action.PointAction">
			<result name="success">/output.jsp</result>
		</action>
		
		<action name="register" class="com.test.action.RegisterAction">
			<result name="success">/success.jsp</result>
			<result name="input">/register2.jsp</result>
			
			<interceptor-ref name="myStack"></interceptor-ref>
			
		</action>
		
	</package>

功能：改变默认继承的拦截器：
七、添加一个默认的拦截器栈，替换原有默认的拦截器，可以应用到所有的Action当中：
<package name="struts2" extends="struts-default">
		
		<interceptors>
			<interceptor name="myInterceptor" class="com.test.interceptor.MyInterceptor">
				<param name="hello">world</param>
			</interceptor>
			
			<interceptor-stack name="myStack">
				<interceptor-ref name="myInterceptor"></interceptor-ref>
				<interceptor-ref name="defaultStack"></interceptor-ref>
			</interceptor-stack>
		</interceptors>
	
		<default-interceptor-ref name="myStack"></default-interceptor-ref>
	
		<action name="login" class="com.test.action.LoginAction">
			<result name="input">/login2.jsp</result>
			<result name="success">/result.jsp</result>
			<result name="failer">login2.jsp</result>
		</action>
		
		<action name="pointConverter" class="com.test.action.PointAction">
			<result name="success">/output.jsp</result>
		</action>
		
		<action name="register" class="com.test.action.RegisterAction">
			<result name="success">/success.jsp</result>
			<result name="input">/register2.jsp</result>
			
		</action>
		
	</package>

功能：在同一目录下再定义一个拦截器MyInterceptor2.java继承自AbstractInterceptor类：
package com.test.interceptor;

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

public class MyInterceptor2 extends AbstractInterceptor {

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

		System.out.println("Intercept2");
		
		String result = invocation.invoke();
		
		return result;
	}
}

八、在struts.xml中配置一下：
<package name="struts2" extends="struts-default">
		
		<interceptors>
			<interceptor name="myInterceptor" class="com.test.interceptor.MyInterceptor">
				<param name="hello">world</param>
			</interceptor>
			
			<interceptor name="myInterceptor2" class="com.test.interceptor.MyInterceptor2">
			</interceptor>
			
			<interceptor name="myInterceptor3" class="com.test.interceptor.MyInterceptor3">
			</interceptor>
			
			<interceptor-stack name="myStack">
			
			<!-- 
				<interceptor-ref name="myInterceptor"></interceptor-ref>
				<interceptor-ref name="myInterceptor2"></interceptor-ref> 
			-->
				
				<interceptor-ref name="defaultStack"></interceptor-ref>
			</interceptor-stack>
		</interceptors>
	
		<default-interceptor-ref name="myStack"></default-interceptor-ref>
	
		<action name="login" class="com.test.action.LoginAction">
			<result name="input">/login2.jsp</result>
			<result name="success">/result.jsp</result>
			<result name="failer">login2.jsp</result>
		</action>
		
		<action name="pointConverter" class="com.test.action.PointAction">
			<result name="success">/output.jsp</result>
		</action>
		
		<action name="register" class="com.test.action.RegisterAction" method="test">
			<result name="success">/success.jsp</result>
			<result name="input">/register2.jsp</result>
			
			
			<interceptor-ref name="myInterceptor3">
				<!-- <param name="includeMethods">test,execute</param> -->
				<param name="excludeMethods">test,execute</param>
				<param name="includeMethods">test</param>
			</interceptor-ref>
			<interceptor-ref name="defaultStack"></interceptor-ref>
			
		</action>
		
	</package>

说明：拦截器执行的先后顺序与拦截器配置的先后顺序有关系，但是在结束的时候后配置的拦截器先结束。
功能：方法拦截器的实现。
九、在com.test.interceptor创建方法拦截器的类MyInterceptor3.java继承自MethodFilterInterceptor父类：
package com.test.interceptor;

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

public class MyInterceptor3 extends MethodFilterInterceptor {

	public void init(){
		System.out.println("init3");
	}
	
	@Override
	protected String doIntercept(ActionInvocation invocation) throws Exception {

		System.out.println("my interceptor3");
		
		String result = invocation.invoke();
		
		return result;
	}
}

十、在struts.xml中进行方法拦截器的配置：
<package name="struts2" extends="struts-default">
		
		<interceptors>
			<interceptor name="myInterceptor" class="com.test.interceptor.MyInterceptor">
				<param name="hello">world</param>
			</interceptor>
			
			<interceptor name="myInterceptor2" class="com.test.interceptor.MyInterceptor2">
			</interceptor>
			
			<interceptor name="myInterceptor3" class="com.test.interceptor.MyInterceptor3">
			</interceptor>
			
			<interceptor-stack name="myStack">
			
			<!-- 
				<interceptor-ref name="myInterceptor"></interceptor-ref>
				<interceptor-ref name="myInterceptor2"></interceptor-ref> 
			-->
				
				<interceptor-ref name="defaultStack"></interceptor-ref>
			</interceptor-stack>
		</interceptors>
	
		<default-interceptor-ref name="myStack"></default-interceptor-ref>
	
		<action name="login" class="com.test.action.LoginAction">
			<result name="input">/login2.jsp</result>
			<result name="success">/result.jsp</result>
			<result name="failer">login2.jsp</result>
		</action>
		
		<action name="pointConverter" class="com.test.action.PointAction">
			<result name="success">/output.jsp</result>
		</action>
		
		<action name="register" class="com.test.action.RegisterAction" method="test">
			<result name="success">/success.jsp</result>
			<result name="input">/register2.jsp</result>
			
			
			<interceptor-ref name="myInterceptor3">
				<!-- <param name="includeMethods">test,execute</param> -->
				<param name="excludeMethods">test,execute</param>
				<param name="includeMethods">test</param>
			</interceptor-ref>
			<interceptor-ref name="defaultStack"></interceptor-ref>
			
		</action>
		
	</package>

说明：includeMethods的属性具有优先级，但对某方法既拦截又不拦截的时候，这个方法是一定会执行的。

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