访问Web元素

访问Web元素可以有四种方法，下面依次列出

user_login_success.jsp

<% @ page language="java" contentType="text/html; charset=utf-8"
    pageEncoding="utf-8" %>
<% @taglib uri="/struts-tags" prefix="s" %>
<! 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 > success </ title >
<%
    String path = request.getContextPath();
    String basePath = request.getScheme() + "://"
            + request.getServerName() + ":" + request.getServerPort()
            + path + "/";
%>
< base  href ="<%=basePath%>"   />
<!--  使用base标签指定本页面所有链接的参照路径  -->
</ head >
< body >

< p > Login success. </ p >
< s:property  value ="#request.r1"   />
|
<% = request.getAttribute( " r1 " ) %>
< br >
< s:property  value ="#session.s1"   />
|
<% = session.getAttribute( " s1 " ) %>
< br >
< s:property  value ="#application.a1"   />
|
<% = application.getAttribute( " a1 " ) %> < br >

< s:debug ></ s:debug >
</ body >
</ html >

 

 

第一种方法：
LoginAction1.java

package  com.bebig.struts2.user.action;

import  java.util.Map;

import  com.opensymphony.xwork2.ActionContext;
import  com.opensymphony.xwork2.ActionSupport;

public   class  LoginAction1  extends  ActionSupport  {
    //取得Map类型的request、session、application
    private Map request;
    private Map session;
    private Map application;

    public LoginAction1() {
        request = (Map) ActionContext.getContext().get("request");
        session = ActionContext.getContext().getSession();
        application = ActionContext.getContext().getApplication();
    }
    
    public String execute()
    {
        request.put("r1", "r1");
        session.put("s1", "s1");
        application.put("a1", "a1");
        return SUCCESS;
    }

}

第二种方法：
LoginAction2.java

package  com.bebig.struts2.user.action;

import  java.util.Map;

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

import  com.opensymphony.xwork2.ActionSupport;

public   class  LoginAction2  extends  ActionSupport  implements  RequestAware,
        SessionAware, ApplicationAware  {
    //三个对象被容器注入
    private Map<String, Object> request;
    private Map<String, Object> session;
    private Map<String, Object> application;

    public String execute() {
        request.put("r1", "r1");
        session.put("s1", "s1");
        application.put("a1", "a1");
        return SUCCESS;
    }

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

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

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

}

第三种方法：
LoginAction3.java

package  com.bebig.struts2.user.action;


import  javax.servlet.ServletContext;
import  javax.servlet.http.HttpServletRequest;
import  javax.servlet.http.HttpSession;
import  org.apache.struts2.ServletActionContext;
import  com.opensymphony.xwork2.ActionSupport;

public   class  LoginAction3  extends  ActionSupport  {
    private HttpServletRequest request;
    private HttpSession session;
    private ServletContext application;

    public LoginAction3() {
        request = ServletActionContext.getRequest();
        session = request.getSession();
        application = session.getServletContext();
    }
    
    public String execute()
    {
        request.setAttribute("r1", "r1");
        session.setAttribute("s1", "s1");
        application.setAttribute("a1", "a1");
        return SUCCESS;
    }

}

第四种方法：
LoginAction4.java

package  com.bebig.struts2.user.action;

import  javax.servlet.ServletContext;
import  javax.servlet.http.HttpServletRequest;
import  javax.servlet.http.HttpSession;

import  org.apache.struts2.interceptor.ServletRequestAware;

import  com.opensymphony.xwork2.ActionSupport;

public   class  LoginAction4  extends  ActionSupport  implements  ServletRequestAware  {
    private HttpServletRequest request;
    private HttpSession session;
    private ServletContext application;

    public String execute() {
        request.setAttribute("r1", "r1");
        session.setAttribute("s1", "s1");
        application.setAttribute("a1", "a1");
        return SUCCESS;
    }

    @Override
    public void setServletRequest(HttpServletRequest request) {
        this.request = request;
        session = request.getSession();
        application = session.getServletContext();
    }

}

总结：
第一种方法依赖于Struts2容器，取得相关对象数据；
第二种方法，依赖注入DI（dependency injection），控制反转IoC（Inverse of control），对象数据被容器注入；
第三种方法，依赖于容器取得相关对象数据；
第四种方法，依赖注入一个对象的数据后，再通过这个对象获取到其它对象数据。
推荐使用第二种方法。
另：取得Map类型request,session,application，真实类型HttpServletRequest,HttpSession,ServletContext的引用：