Struts2学习第四课通过Aware接口获取WEB资源

使用XxxAware接口

看代码：

package logan.struts2.study;

import java.util.Map;

import org.apache.struts2.interceptor.ApplicationAware;

public class TestAwareAction implements ApplicationAware{
    
    public String execute(){
        
        //1.向application中加入一个属性：applicationKey2 - applicationValue2
        application.put("applicationKey2", "applicationValue2");
        
        //2.从application中读取一个属性，date,并打印。
        System.out.println(application.get("date"));
        return "success";
    }
    
    private Map<String,Object> application;

    @Override
    public void setApplication(Map<String, Object> application) {
        // TODO Auto-generated method stub
        this.application = application;
        
    }

}

struts.xml

<?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>
    <!-- action  VS  Action类
    action:代表一个Struts2的一个请求
    Action类：能够处理Struts2请求的类
     -->
    <package name="default" namespace="/" extends="struts-default">
    
        <action name="TestActionContext" class="logan.struts2.study.TestActionContext">
            <result>/test-actionContext.jsp</result>
        </action>
        
        <action name="TestAware" class="logan.struts2.study.TestAwareAction">
            <result>/test-aware.jsp</result>
        </action>
    
    </package>
    
</struts>

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>Struts2-2</display-name>
  
  <filter>
      <filter-name>struts2</filter-name>
      <filter-class>org.apache.struts2.dispatcher.filter.StrutsPrepareAndExecuteFilter</filter-class>
  </filter>
  
  <filter-mapping>
      <filter-name>struts2</filter-name>
      <url-pattern>/*</url-pattern>
  </filter-mapping>
  
  <welcome-file-list>
      <welcome-file>index.html</welcome-file>
  </welcome-file-list>
</web-app>

index.jsp

<%@page import="java.util.Date"%>
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
    <a href="TestActionContext.action?name=logan&name=logan2">Test ActionContext</a>
    <br><br>
    <a href="TestAware.action?name=logan">Test Aware</a>
    <%
        if(application.getAttribute("date") == null){
            application.setAttribute("date", new Date());
            
        }
    %>
    
</body>
</html>

test-aware.jsp

<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
    pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Insert title here</title>
</head>
<body>
        <h4>Test Aware Page</h4>
        application:${applicationScope.applicationKey2 }
</body>
</html>

访问地址：

http://localhost:8080/Struts2-3/index.jsp

还可以这样写：

package logan.struts2.study;

import java.util.Map;

import org.apache.struts2.interceptor.ApplicationAware;
import org.apache.struts2.interceptor.ParameterAware;
import org.apache.struts2.interceptor.RequestAware;
import org.apache.struts2.interceptor.SessionAware;

public class TestAwareAction implements ApplicationAware,SessionAware,RequestAware{
    
    public String execute(){
        
        //1.向application中加入一个属性：applicationKey2 - applicationValue2
        application.put("applicationKey2", "applicationValue2");
        
        //2.从application中读取一个属性，date,并打印。
        System.out.println(application.get("date"));
        return "success";
    }
    
    private Map<String,Object> application;

    @Override
    public void setApplication(Map<String, Object> application) {
        // TODO Auto-generated method stub
        this.application = application;
        
    }

    @Override
    public void setRequest(Map<String, Object> arg0) {
        // TODO Auto-generated method stub
        
    }

    @Override
    public void setSession(Map<String, Object> arg0) {
        // TODO Auto-generated method stub
        
    }

}

选用建议：若一个Action类中有多个action方法，且多个方法都需要使用域对象的Map或parameters，则建议使用接口的方式。

如下修改代码：

package logan.struts2.study;

import java.util.Map;

import org.apache.struts2.dispatcher.Parameter;
import org.apache.struts2.dispatcher.SessionMap;

import com.opensymphony.xwork2.ActionContext;

public class TestActionContext {
    
    public String execute(){
        //0.获取ActionContext对象
        //ActionContext是Action的上下文对象，可以从中获取到当前Action需要的一切信息
        ActionContext actionContext = ActionContext.getContext();
        
        //1.获取application对应的Map，并想其中添加一个属性
        //通过调用ActionContext 对象的getApplication()方法来获取application对象的Map对象
        Map<String, Object> applicationMap = actionContext.getApplication();
        //设置属性
        applicationMap.put("applicationKey", "applicationValue");
        //获取属性
        Object date = applicationMap.get("date");
        System.out.println(date);
        
        //2.session
        Map<String,Object> sessionMap = actionContext.getSession();
        sessionMap.put("sessionKey", "sessionValue");
        if(sessionMap instanceof SessionMap){
            SessionMap sm = (SessionMap) sessionMap;
            sm.invalidate();
            System.out.println("session 失效了");
        }
        
        
        //3.request
        //ActionContext中并没有提供getRequest方法来获取Request对应的Map
        //需要手工调用get()方法，传入request字符串来获取。
        Map<String,Object> requestMap = (Map<String, Object>) actionContext.get("request");
        requestMap.put("requestKey", "requestValue");
        
        //4.获取请求参数对应的Map，并获取指定的参数值
        //parameters这个Map只能读，不能写。如果写入，不会报错，但是也不起作用。
        Map<String,Parameter> parameters = actionContext.getParameters();
        System.out.println(parameters.get("name"));
        
        return "success";
    }

}

这样就获取不到session

sessionMap对应的Map实际上是SessionMap类型的，强转后若调用其invalidate()方法，可以使其session失效。

Struts2学习第四课 通过Aware接口获取WEB资源

Struts2学习第四课通过Aware接口获取WEB资源