struts2 页面元素获取

//1package com.bjsxt.struts2.user.action;import java.util.Map;import com.opensymphony.xwork2.ActionContext;import com.opensymphony.xwork2.ActionSupport;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;  }  }//2package 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; 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; }  }//3package 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;  } }//4package 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(); } }