在Struts2中访问Web页面元素request、response、session、application的四种方法

在Struts2中获取Web页面元素request、response、session、application有两种形式，一种是Map类型，另一种是真实类型HttpServletRequest, HttpSession, ServletContext的引用。一共有四种获取方法 ，如下所示：

第一种：依赖于容器，Map类型：

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();
}

第二种：使用IOC，Map类型，推荐使用的一种方式：

public class LoginAction2 extends ActionSupport implements
	RequestAware, SessionAware, ApplicationAware {  
	private Map<String, Object> request;
	private Map<String, Object> session;
	private Map<String, Object> application;
	public void setRequest(Map<String, Object> request) {
		this.request = request;
	}
	public void setSession(Map<String, Object> session) {
		this.session = session;
	}
	public void setApplication(Map<String, Object> application) {
		this.application = application;

}

第三种：依赖于容器，原始类型：

private HttpServletRequest request;
private HttpSession session;
private ServletContext application;
public LoginAction3(){
	request = ServletActionContext.getRequest();
	session = request.getSession();
	application = session.getServletContext();
}

第四种：IOC，原始类型

public class LoginAction4 extends ActionSupport 
     implements ServletRequestAware {
	private HttpServletRequest request;
	private HttpSession session;
	private ServletContext application;
	public void setServletRequest(HttpServletRequest request) {
		this.request = request;
		this.session = this.request.getSession();
		this.application = this.session.getServletContext();
	}