什么是与Servlet API解耦？

为了避免与servlet API耦合在一起，方便Action做单元测试，

Struts2对HttpServletRequest，HttpSession，和ServletContext进行了封装，构造了3个Map对象来替代这三个对象，在Action中可以直接使用HttpServletRequest，HttpSession，ServletContext对应的Map对象来保存和读取数据。

 

两种解耦方式：

1、    使用Struts2提供的工具类中提供的静态方法，得到对用的封装后对象。

　　

package cn.itcast.context;import java.util.Map;import javax.servlet.ServletContext;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.struts2.ServletActionContext;import com.opensymphony.xwork2.ActionSupport;public class ContextAction extends ActionSupport {    /**     *      */    private static final long serialVersionUID = 1L;    public String test() throws Exception{        System.out.println("ContextAction ****** test()");                HttpServletRequest request=ServletActionContext.getRequest();        request.setAttribute("username","username_request");                HttpServletResponse response=ServletActionContext.getResponse();                Map sessionMap=ServletActionContext.getContext().getSession();        sessionMap.put("username", "username_session");                ServletContext sc=ServletActionContext.getServletContext();        sc.setAttribute("username", "username_application");                return "attr";    }}

 

2、    Action实现ServletRequestAware，ServletResponseAware，ServletContextAware，SessionAware四个接口，分别重写对应的set方法，达到操作该4个封装后对象。

package cn.itcast.context;import java.util.Map;import javax.servlet.ServletContext;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import javax.servlet.http.HttpSession;import org.apache.struts2.ServletActionContext;import org.apache.struts2.interceptor.ServletRequestAware;import org.apache.struts2.interceptor.ServletResponseAware;import org.apache.struts2.interceptor.SessionAware;import org.apache.struts2.util.ServletContextAware;import com.opensymphony.xwork2.ActionSupport;public class Context02Action extends ActionSupport     implements ServletRequestAware,ServletResponseAware,ServletContextAware,SessionAware{    HttpServletRequest request;    HttpServletResponse response;    ServletContext context;    Map
     
       sessionMap;        private static final long serialVersionUID = 1L;    public String test() throws Exception{        System.out.println("ContextAction ****** test()");                HttpServletRequest request=ServletActionContext.getRequest();        request.setAttribute("username","username_request");                HttpServletResponse response=ServletActionContext.getResponse();                Map sessionMap=ServletActionContext.getContext().getSession();        sessionMap.put("username", "username_session");                ServletContext sc=ServletActionContext.getServletContext();        sc.setAttribute("username", "username_application");                return "attr";    }    public void setSession(Map
      
        session) {        this.sessionMap=session;    }    public void setServletContext(ServletContext context) {        this.context=context;            }    public void setServletResponse(HttpServletResponse response) {        this.response=response;    }    public void setServletRequest(HttpServletRequest request) {        this.request=request;            }}
      
     

 

 

两种方式没有好坏之分，全凭个人喜好！

 

其他代码：

      
           
                
                     
         
          /context/success.jsp
                      
         
          /context/attr.jsp
                  
                 
                     
         
          /context/success.jsp
                      
         
          /context/attr.jsp
                  
             
           
      

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@ taglib prefix="s" uri="/struts-tags" %><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%>                      
          
          
              
          
          
                textContext
    testContext
  

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@ taglib prefix="s" uri="/struts-tags" %><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%>                      
          
          
              
          
          
                xxxxxxxxxxxxxx
  

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%@ taglib prefix="s" uri="/struts-tags" %><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%>                      
          
          
              
          
          
                ${requestScope.username }
    ${sessionScope.username }
    ${applicationScope.username }