如何在Action中获取：request，session，application。
共四种方式，示例在下面给出，其中第二种常用。【注意1】：我们需要知道前两种方法得到的是Map<String,Object>,而后两种方式得到的才是真正的request等对象。而Map就是把request对象中的属性取出做成了键值对而已。【注意2】：另外如果就是为了在action和jsp传递参数的话，只需要在action中定义成员，然后Jsp中利用struts标签<s:property value="name"/>就能够访问到数据，而这些内容都是被保存在了value stack中。关于value stack 和 stack context 会在后面得内容涉及。?方法一：public class LoginAction1 extends ActionSupport {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;}}方法二：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 controlpublic String execute() {request.put("r1", "r1");session.put("s1", "s1");application.put("a1", "a1");return SUCCESS;}? @Overridepublic void setRequest(Map<String, Object> request) {this.request = request;}@Overridepublic void setSession(Map<String, Object> session) {this.session = session;}@Overridepublic void setApplication(Map<String, Object> application) {this.application = application;}}方法三：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;}}方法四：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;} @Overridepublic void setServletRequest(HttpServletRequest request) {this.request = request;this.session = request.getSession();this.application = session.getServletContext();}}