9.Struts2在Action中获取request-session-application对象

为避免与Servlet API耦合在一起,方便Action类做单元测试.
Struts2对HttpServletRequest、HttpSession、ServletContext进行了封装,构造了三个Map对象来替代这三种对象。
注意,这三个对象与Servlet API中的三个对象是相同的。
即,在Action中放入Session中信息,在JSP页面中是可以读出来的。
方式一:通过使用ActionContext类获取
在Struts2框架中,通过Action的执行上下文类ActionContext,可以获取request/session/application对象。

ActionContext对象本身就是request范围的存储空间。

所以,对于向request范围中添加属性,直接向ActionContext对象中添加即可。

ActionContext ctx = ActionContext.getContext();
Map<String,Object> application = ctx.getApplication(); Map<String,Object> session = ctx.getSession();
application.put(“app”, “应用范围”);
                                 //往ServletContext里放入app  session.put(“ses”, “session范围”); //往session里放入ses  ctx.put(“req”, “request范围”); //往request里放入req
 
代码文档目录如下:

9.Struts2在Action中获取request-session-application对象_第1张图片

 


 index.jsp源码如下:

<%@ page language="java" import="java.util.*" pageEncoding="ISO-8859-1"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'index.jsp' starting page</title>
    <meta http-equiv="pragma" content="no-cache">
    <meta http-equiv="cache-control" content="no-cache">
    <meta http-equiv="expires" content="0">    
    <meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
    <meta http-equiv="description" content="This is my page">
    <!--
    <link rel="stylesheet" type="text/css" href="styles.css">
    -->
  </head>
  
  <body>
    This is my JSP page. <br>
  </body>
</html>

 show.jsp源码如下:

<%@ page pageEncoding="utf-8" isELIgnored="false"%>

<html>
  <head>  
    <title>show page</title>
  </head>
  
  <body>
  
      application中的app=${applicationScope.app}<br/> 
      session中的ses=${sessionScope.ses}<br/>
      request中的req=${requestScope.req}   

  </body>
</html>

  ScopeTestAction.java源码如下:

package actions;

import java.util.Map;

import com.opensymphony.xwork2.ActionContext;

public class ScopeTestAction {
    public String execute(){
        ActionContext ctx=ActionContext.getContext();
        Map<String,Object> application=ctx.getApplication();
        Map<String,Object> session=ctx.getSession();
        
        application.put("app","app scope");
        session.put("ses","ses scope");
        
        //request中放入属性req
        ctx.put("req", "req scope");
        
        return "success";
    }

}

 web.xml配置如下:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
    xmlns="http://java.sun.com/xml/ns/javaee" 
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
    http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
    
        <filter>
        <filter-name>struts2</filter-name>
        <filter-class>org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter</filter-class>
        </filter>

        <filter-mapping>
        <filter-name>struts2</filter-name>
        <url-pattern>/*</url-pattern>
        </filter-mapping>
    
  <welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
  </welcome-file-list>
</web-app>

struts.xml配置如下:

<?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="one" extends="struts-default">
    
        <action name="scope" class="actions.ScopeTestAction">
            <result>/show.jsp</result>
        </action>
        
    </package>
    
</struts>

 部署发布,启动tomcat,输入地址:

http://127.0.0.1:8080/request_session_application/scope.action

运行截图如下:

9.Struts2在Action中获取request-session-application对象_第2张图片


 方式二:通过实现特定接口来获取

通过让Action实现特定接口,也可获取request/session/application对象。
 RequestAware接口:该接口中只有一个方法
    public void setRequest(Map<String,Object> request)
 SessionAware接口:该接口中只有一个方法
    public void setSession (Map<String,Object> session)
 ApplicationAware接口:该接口中只有一个方法
    public void setApplication (Map<String,Object> application)
只要在Action中以如下的形式定义好相应的对象:
            Map<String,Object> request;
并以如下的方式实现特定接口中的方法:
            this.request = request;
那么,在Action方法中(如execute方法)就可使用相应的对象了。
对这些对象的访问:
在各范围中放入属性后,在页面中即可通过EL表达式将其值读出来了。
    ${requestScope.req}   <br/>
    ${sessionScope.ses}   <br/>
    ${applicationScope.app}
实例:在Action中获取request/session/application—scopetest
Step1:编写ScopeTestAction与ScopeTestAction2类,来实现使用两种方式的添加相应习属性的功能
Step2:编写web.xml与struts.xml
Step3:编写show.jsp
在上面的基础上新建ScopeTestAction2.java
9.Struts2在Action中获取request-session-application对象_第3张图片
9.Struts2在Action中获取request-session-application对象_第4张图片9.Struts2在Action中获取request-session-application对象_第5张图片
9.Struts2在Action中获取request-session-application对象_第6张图片
完成源码如下:
package actions;

import java.util.Map;

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

public class ScopeTestAction2 implements RequestAware, SessionAware,ApplicationAware {
    private Map<String,Object> request;
    private Map<String,Object> session;
    private Map<String,Object> application;


    
    public void setRequest(Map<String, Object> request) {
        this.request = request;
    }



    public void setSession(Map<String, Object> session) {
        this.session = session;
    }



    public void setApplication(Map<String, Object> application) {
        this.application = application;
    }


    public String execute(){
        
        application.put("app","app scope");
        session.put("ses","ses scope");
        
        //request中放入属性req
        request.put("req", "req scope");
        return "success";
    }

}

 修改后struts.xml文件如下:

<?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="one" extends="struts-default">
    
    
        <action name="scope" class="actions.ScopeTestAction">
            <result>/show.jsp</result>
        </action>
        <action name="scope2" class="actions.ScopeTestAction2">
            <result>/show.jsp</result>
        </action>
        
    </package>
    
</struts>

重新部署发布,启动tomcat,输入地址:

http://127.0.0.1:8080/request_session_application/scope2.action

9.Struts2在Action中获取request-session-application对象_第7张图片


 

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