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struts2.3.8随笔

在Struts2中提供了一种机制访问Request, Session, Application.(在Action中访问Web元素)

<?xml version="1.0" encoding="GB18030" ?>
<%@ page language="java" contentType="text/html; charset=GB18030"
    pageEncoding="GB18030"%>

<% String context = request.getContextPath(); %>

<!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>
取得Map类型request,session,application,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</li> (只用这种)
	<li>后三者：依赖于容器</li>
	<li>后三者：IOC</li>
</ol>
<br />
<form name="f" action="" method="post">
用户名：<input type="text" name="name"/>
密码：<input type="text" name="password"/>
<br />
<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>	
</body>
</html>

第一种：依赖于容器，取得Map类型的request,session,application

在Map与HttpRequest之间做了映射，将Map中的值放到Request中，看源码。

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() {
       /*1.ActionContext.getContext()是单例吗？不是单例，其实你想想就知道了，不可能是单例，因为每个不同的请求里面，request里面放的值是不样的。
        如果是单例的话，你只能放同一个request里面，那就不对了。推荐看看源码，其实是一个ThreadLocal
        */
		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(推荐，只用这一种)：IOC(也叫DI)，取得Map类型的request,session,application

在Map与Request做了映射，将Request中的值放到Map中，看源码。

IOC(Inverse of Control)控制反转，本来是Action自己控制的request的值，现在将request的值交给了Struts2来控制

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;

public class LoginAction2 extends ActionSupport implements RequestAware,SessionAware, ApplicationAware {
	
	private Map<String, Object> request;//本来是Action控制request的值，现在将request的值交给了Struts2来控制
	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;
	}
	
	
}

第三种(不推荐)：依赖于容器，真实类型 HttpServletRequest, HttpSession, ServletContext的引用

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;

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(不推荐)：IOC，真实类型 HttpServletRequest, HttpSession, ServletContext的引用

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;

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;
		this.session = request.getSession();
		this.application = session.getServletContext();
	}
	
}

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2015-03-07 11:03
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