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 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;
}
}

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;
}

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