Struts2拦截器介绍

2023-01-08 12:47:48

一、拦截器简介

Struts拦截器和Action的关系如图：

Struts2拦截器介绍

为了在使用拦截器时制定参数值，应通过<interceptor-ref …/>元素添加<param …/>子元素来为拦截器指定参数值。下面是配置拦截器动态指定参数值的语法。

  1: <interceptor-stack name="拦截器栈一">



  2:     <interceptor-ref name="拦截器一">



  3:         <param name="参数一">参数值一</param>



  4:         <param name="参数二">参数值二</param>



  5:     </interceptor-ref>



  6: </interceptor-stack>

二、自定义拦截器

1、简单的拦截器

用户要开发自己的拦截器，需要实现com.opensymphony.xwork2.interceptor.Interceptor接口。下面实现了一个简单的拦截器

1、SimpleInterceptor.java

  1: package cc.openhome;



  2: import java.util.Date;



  3: import com.opensymphony.xwork2.ActionInvocation;



  4: import com.opensymphony.xwork2.interceptor.AbstractInterceptor;



  5: public class SimpleInterceptor extends AbstractInterceptor {



  6:   //简单的拦截器的名字



  7:   private String name;



  8:   //为该简单拦截器设置名字的setter方法



  9:   //拦截Action方法的intercept方法



 10:   @Override



 11:   public String intercept(ActionInvocation invocation) throws Exception {



 12:     // TODO Auto-generated method stub



 13:     //取得被拦截的Action实例



 14:     LoginAction action = (LoginAction) invocation.getAction();



 15:     //打印



 16:     System.out.println("正在执行 ‘"+name+"’ 拦截器的动作========"+"开始执行登录的时间为："+new Date());



 17:     //取得开始执行Action的时间



 18:     long start = System.currentTimeMillis();



 19:     //执行该拦截器的后一个拦截器，或者直接指定Action的execute()方法



 20:     String result = invocation.invoke();



 21:     System.out.println("正在执行 ‘"+name+" ’拦截器的动作========"+"执行完登录的时间为："+new Date());



 22:     //取得执行完Action的时间



 23:     long end = System.currentTimeMillis();



 24:     System.out.println("正在执行 ‘"+name+"’ 拦截器的动作========"+"Action执行了"+(end-start)+"毫秒");



 25:     return result;



 26:   }



 27:   public String getName() {



 28:     return name;



 29:   }



 30:



 31:   public void setName(String name) {



 32:     this.name = name;



 33:   }



 34: }



 35:

2、struts.xml

  1: <?xml version="1.0" encoding="UTF-8" ?>



  2: <!DOCTYPE struts PUBLIC



  3:   "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"



  4:   "http://struts.apache.org/dtds/struts-2.3.dtd">



  5: <struts>



  6:   <package name="struts2" extends="struts-default">



  7:     <!-- 配置应用所使用的拦截器 -->



  8:         <interceptors>



  9:           <!-- 配置mysimple拦截器 -->



 10:           <interceptor name="mysimple" class="cc.openhome.SimpleInterceptor">



 11:             <!-- 为该拦截器指定参数值 -->



 12:             <param name="name">简单拦截器</param>



 13:           </interceptor>



 14:           <interceptor name="authority" class="cc.openhome.AuthorityInterceptor"/>



 15:         </interceptors>



 16:         <action name="login" class="cc.openhome.LoginAction">



 17:           <result name="success">/success.jsp</result>



 18:           <result name="error">/error.jsp</result>



 19:           <result name="input">/denglu.jsp</result>



 20:           <interceptor-ref name="defaultStack"/>



 21:           <interceptor-ref name="mySimple">



 22:               <param name="name">动态拦截器</param>



 23:           </interceptor-ref>



 24:         </action>



 25:     </package>



 26: </struts>

3、登录页面login.jsp

  1: <%@ page language="java" contentType="text/html; charset=UTF-8"



  2:     pageEncoding="UTF-8"%>



  3: <%@ taglib prefix="s" uri="/struts-tags"%>



  4: <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">



  5: <html>



  6:   <head>



  7:     <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">



  8:     <title>登录界面</title>



  9:   </head>



 10:   <body>



 11:     <s:form action="login">



 12:       <s:textfield name="username" label="用户名"/>



 13:       <s:textfield name="password" label="密    码"/>



 14:       <s:submit value="登录"/>



 15:     </s:form>



 16:   </body>



 17: </html>

4、LoginAction.java

  1: package cc.openhome;



  2: import com.opensymphony.xwork2.Action;



  3: import com.opensymphony.xwork2.ModelDriven;



  4: public class LoginAction  implements Action{



  5:   private String username;



  6:   private String password;



  7:   public String getUsername() {



  8:     return username;



  9:   }



 10:   public void setUsername(String username) {



 11:     this.username = username;



 12:   }



 13:   public String getPassword() {



 14:     return password;



 15:   }



 16:   public void setPassword(String password) {



 17:     this.password = password;



 18:   }



 19:   @Override



 20:   public String execute() throws Exception {



 21:     // TODO Auto-generated method stub



 22:     return SUCCESS;



 23:   }



 24: }



 25:

5、运行结果

Struts2拦截器介绍

2、拦截器的执行顺序

修改struts.xml如下

  1: <?xml version="1.0" encoding="UTF-8" ?>



  2: <!DOCTYPE struts PUBLIC



  3:   "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"



  4:   "http://struts.apache.org/dtds/struts-2.3.dtd">



  5: <struts>



  6:   <constant name="struts.custom.i18n.resources" value="messageResource"></constant>



  7:   <package name="openhome" extends="struts-default">



  8:     <!-- 配置应用所使用的拦截器 -->



  9:         <interceptors>



 10:           <!-- 配置mysimple拦截器 -->



 11:           <interceptor name="mysimple" class="cc.openhome.SimpleInterceptor">



 12:             <!-- 为该拦截器指定参数值 -->



 13:             <param name="name">简单拦截器</param>



 14:           </interceptor>



 15:         </interceptors>



 16:     <action name="login" class="cc.openhome.LoginAction" method="execute">



 17:       <result name="input">/input.jsp</result>



 18:       <result name="success">/WEB-INF/page/welcome.jsp</result>



 19:       <result name="error">/WEB-INF/page/error.jsp</result>



 20:       <interceptor-ref name="defaultStack" />



 21:       <interceptor-ref name="mysimple">



 22:         <param name="name">第一个动态拦截器</param>



 23:       </interceptor-ref>



 24:       <interceptor-ref name="mysimple">



 25:         <param name="name">第二个动态拦截器</param>



 26:       </interceptor-ref>



 27:     </action>



 28:   </package>



 29:     <!-- Add packages here -->



 30: </struts>



 31:

运行结果如下：可以看到先配置的拦截器，先获得执行机会。

Struts2拦截器介绍

3、方法拦截器

如果不需要拦截特定的方法，假如不拦截execute方法，则在控制台上就不会输出任何信息。

只需要修改提供方法过滤的拦截器

MyFilterInterceptor.java

  1: package cc.openhome;



  2: import java.util.Date;



  3: import com.opensymphony.xwork2.ActionInvocation;



  4: import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;



  5: public class MyFilterInterceptor extends MethodFilterInterceptor {



  6:   private String name;



  7:   public String getName() {



  8:     return name;



  9:   }



 10:   public void setName(String name) {



 11:     this.name = name;



 12:   }



 13:   @Override



 14:   protected String doIntercept(ActionInvocation invocation) throws Exception {



 15:     // TODO Auto-generated method stub



 16:     //取得被拦截的Action实例



 17:         LoginAction action = (LoginAction) invocation.getAction();



 18:



 19:         //打印



 20:         System.out.println("正在执行 ‘"+name+"’ 拦截器的动作========"+"开始执行登录的时间为："+new Date());



 21:



 22:         //取得开始执行Action的时间



 23:         long start = System.currentTimeMillis();



 24:



 25:         //执行该拦截器的后一个拦截器，或者直接指定Action的execute()方法



 26:         String result = invocation.invoke();



 27:         System.out.println("正在执行 ‘"+name+" ’拦截器的动作========"+"执行完登录的时间为："+new Date());



 28:



 29:         //取得执行完Action的时间



 30:         long end = System.currentTimeMillis();



 31:         System.out.println("正在执行 ‘"+name+"’ 拦截器的动作========"+"Action执行了"+(end-start)+"毫秒");



 32:         return result;



 33:   }



 34: }



 35:

struts.xml

  1: <?xml version="1.0" encoding="UTF-8" ?>



  2: <!DOCTYPE struts PUBLIC



  3:   "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"



  4:   "http://struts.apache.org/dtds/struts-2.3.dtd">



  5: <struts>



  6:   <package name="openhome" extends="struts-default">



  7:     <!-- 配置应用所使用的拦截器 -->



  8:         <interceptors>



  9:           <!-- 配置myfilter拦截器 -->



 10:           <interceptor name="myfilter" class="cc.openhome.MyFilterInterceptor">



 11:             <!-- 为该拦截器指定参数值 -->



 12:             <param name="name">方法过滤拦截器</param>



 13:           </interceptor>



 14:           </interceptor>



 15:           <interceptor name="authority" class="cc.openhome.AuthorityInterceptor"/>



 16:         </interceptors>



 17:     <action name="login" class="cc.openhome.LoginAction" method="execute">



 18:       <result name="input">/input.jsp</result>



 19:       <result name="success">/WEB-INF/page/welcome.jsp</result>



 20:       <result name="error">/WEB-INF/page/error.jsp</result>



 21:       <interceptor-ref name="defaultStack" />



 22:       <interceptor-ref name="myfilter">



 23:         <param name="name">改名后的方法拦截器</param>



 24:         <param name="excludeMethods">execute</param>



 25:       </interceptor-ref>



 26:     </action>



 27:   </package>



 28:     <!-- Add packages here -->



 29: </struts>



 30:

3、拦截结果的监听器

为了更精确的定义在execute方法执行前后的结构，以及执行后再处理Result执行的动作。这个监听器通过手动注册在拦截内部，必须实现PreReslutListener接口。

MyPreResultListener.java

  1: package cc.openhome;



  2: import com.opensymphony.xwork2.ActionInvocation;



  3: import com.opensymphony.xwork2.interceptor.PreResultListener;



  4: public class MyPreResultListener implements PreResultListener {



  5:   @Override



  6:   public void beforeResult(ActionInvocation invocation, String resultCode) {



  7:     // TODO Auto-generated method stub



  8:     System.out.println("返回的逻辑视图是："+resultCode);



  9:   }



 10: }



 11:

    BeforeResultInterceptor.java

  1: package cc.openhome;



  2: import com.opensymphony.xwork2.ActionInvocation;



  3: import com.opensymphony.xwork2.interceptor.AbstractInterceptor;



  4: public class BeforeResultInterceptor extends AbstractInterceptor {



  5:   @Override



  6:   public String intercept(ActionInvocation invocation) throws Exception {



  7:     // TODO Auto-generated method stub



  8:     //将一个拦截器结果的监听器注册给该拦截器



  9:     invocation.addPreResultListener(new MyPreResultListener());



 10:     System.out.println("execute方法执行之前的拦截。。。");



 11:     //调用下一个拦截器，或者Action的执行方法execute()



 12:     String result = invocation.invoke();



 13:     System.out.println("execute方法执行之后的拦截。。。");



 14:     return result;



 15:   }



 16: }



 17:

    struts.xml

  1: <?xml version="1.0" encoding="UTF-8" ?>



  2: <!DOCTYPE struts PUBLIC



  3:   "-//Apache Software Foundation//DTD Struts Configuration 2.3//EN"



  4:   "http://struts.apache.org/dtds/struts-2.3.dtd">



  5: <struts>



  6:   <constant name="struts.custom.i18n.resources" value="messageResource"></constant>



  7:   <package name="openhome" extends="struts-default">



  8:     <!-- 配置应用所使用的拦截器 -->



  9:         <interceptors>



 10:           <!-- 配置myresult拦截器 -->



 11:           <interceptor name="myresult" class="cc.openhome.BeforeResultInterceptor">



 12:             <!-- 为该拦截器指定参数值 -->



 13:             <param name="name">结果的拦截器</param>



 14:           </interceptor>



 15:         </interceptors>



 16:     <action name="login" class="cc.openhome.LoginAction" method="execute">



 17:       <result name="input">/input.jsp</result>



 18:       <result name="success">/WEB-INF/page/welcome.jsp</result>



 19:       <result name="error">/WEB-INF/page/error.jsp</result>



 20:       <interceptor-ref name="defaultStack" />



 21:       <interceptor-ref name="myresult">



 22:         <param name="name">结果拦截器</param>



 23:       </interceptor-ref>



 24:     </action>



 25:     <!-- Add packages here -->



 26: </struts>



 27:

    运行结果

Struts2拦截器介绍

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