1.访问Map类的request，session，application
第一种方式：依赖于Struts
a.编写action
package com.bjsxt.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() {
/*ActionContext.getContext()获取action执行环境，这个环境中有Map类型的request，session，aplication
*problem1：ActionContext是单例吗？不是，每个请求都会生成一个ActionContext，request对象不可能所有的用户都使用同一个
*problem2：Map类型的request，session，application与HttpServletRequest，HtppSession，ServletContext是一样吗? Map类型的request中内容会copy到HttpServletRequest对象当中去，因此在页面当中也可以使用
*/
request = (Map)ActionContext.getContext().get("request");//与Stack Context中的request对应
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;
}
}
b.在页面当中访问Map类型的request，session，application
<?xml version="1.0" encoding="GB18030" ?>
<%@ page language="java" contentType="text/html; charset=GB18030"
pageEncoding="GB18030"%>
<%@taglib uri="/struts-tags" prefix="s" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=GB18030" />
<title>Insert title here</title>
</head>
<body>
User Login Success!
<br />
使用OGNL表达式访问Map类型的request|使用原始的方式访问HttpServletRequest中的内容
<!--获取Stack Context中的request中的内容-->
<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><!--查看Value stack contents与Stack Context中的内容-->
<br />
</body>
</html>
第二种方式（最常用）：使用DI（依赖注入）方式获得Map类型Request，session，application
package com.bjsxt.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.ActionContext;
import com.opensymphony.xwork2.ActionSupport;
//需要实现 RequestAware,SessionAware, ApplicationAware接口
public class LoginAction2 extends ActionSupport implements RequestAware,SessionAware, ApplicationAware {
private Map<String, Object> request;
private Map<String, Object> session;
private Map<String, Object> application;
//DI dependency injection
//IoC inverse of control
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;
}
}