访问web元素(?)

                     访问web元素：取得Map类型request,session,application,真实类型 HttpServletRequest, HttpSession, ServletContext的引用(不懂)

//index.jsp
取得Map类型request,session,application；
		取真实类型 HttpServletRequest,HttpSession,ServletContext的引用:
		<ol>
			<li>
				前三者：依赖于容器
			</li>
			<li>
				前三者：IOC(只用这种，控制反转)
			</li>
			<li>
				后三者：依赖于容器
			</li>
			<li>
				后三者：IOC
			</li>
		</ol>
		<br /><!-- name = f -->
		<form name="f" action="" method="post">
			用户名：
			<input type="text" name="name" />
			密码：
			<input type="text" name="password" />
			<br /><!-- 多种按钮提交同一 form--> <!-- document.f取到form，用javaScript多态指定 -->
			<input type="button" value="submit1"
				onclick="javascript:document.f.action='login/login1';document.f.submit();" />
			<input type="button" value="submit2"
				onclick="javascript:document.f.action='login/login2';document.f.submit();" />
			<input type="button" value="submit3"
				onclick="javascript:document.f.action='login/login3';document.f.submit();" />
			<input type="button" value="submit4"
				onclick="javascript:document.f.action='login/login4';document.f.submit();" />
		</form>


//user_login_success.jsp
User Login Success!
		<br />
		<s:property value="#request.r1" /> <!-- s:property 用标签形式访问Stack Context -->
		|
		<%=request.getAttribute("r1")%> <!-- 用JSP访问，取key = r1的值 -->
		<br />
		<s:property value="#session.s1" />
		|
		<%=session.getAttribute("s1")%>
		<br />
		<s:property value="#application.a1" />
		|
		<%=application.getAttribute("a1")%>
		<br />
		<s:property value="#attr.a1" /> <!-- attribute会搜session和application，分不清楚具体访问哪个(很少用) -->
		<br />
		<s:property value="#attr.s1" />
		<br />
		<s:property value="#attr.r1" />
		<br />
		<s:debug></s:debug>
		<br />

//struts.xml配置
<package name="login" extends="struts-default" namespace="/login">
        <action name="login*" class="com.bjsxt.struts2.user.action.LoginAction{1}">
            <result>/user_login_success.jsp</result>
        </action>
    </package>

//action
package com.bjsxt.struts2.user.action;

import java.util.Map;

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

@SuppressWarnings("serial")
public class LoginAction1 extends ActionSupport {
	
	private Map<String, Object> request;
	private Map<String, Object> session;
	private Map<String, Object> application;
	
	@SuppressWarnings("unchecked")
	public LoginAction1() {
		request = (Map)ActionContext.getContext().get("request"); //取得request的值
		session = ActionContext.getContext().getSession(); //拿到action执行的上下文
		application = ActionContext.getContext().getApplication();
	}
	
	public String execute() {
		request.put("r1", "r1"); //向容器map中放入值，同时复制HttpServletRequest对象
		session.put("s1", "s1"); //key——value
		application.put("a1", "a1");
		return SUCCESS; 
	}
}



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.ActionSupport;

@SuppressWarnings("serial")
public class LoginAction2 extends ActionSupport implements RequestAware,SessionAware,ApplicationAware {
	
	private Map<String, Object> request;  //key —— String
	private Map<String, Object> session;   // value —— Object
	private Map<String, Object> application;
	
	//DI dependency injection   依赖注入
	//IoC inverse of control    控制反转
	public String execute() {
		request.put("r1", "r1"); //其他人调用时，往request注入值，不用自己初始化，拿来就可以用了
		session.put("s1", "s1");
		application.put("a1", "a1");
		return SUCCESS; 
	}

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

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

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




package com.bjsxt.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;

@SuppressWarnings("serial")
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; 
	}

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




package com.bjsxt.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;

@SuppressWarnings("serial")
public class LoginAction3 extends ActionSupport {
	
	private HttpServletRequest request;
	private HttpSession session;
	private ServletContext application;
	
	public LoginAction3() {
		request = ServletActionContext.getRequest(); //拿到request
		session = request.getSession();   //拿到session
		application = session.getServletContext();
	}
	
	public String execute() {
		request.setAttribute("r1", "r1");
		session.setAttribute("s1", "s1");
		application.setAttribute("a1", "a1");
		return SUCCESS; 
	}
	
}