struts2访问servletAPI

1、原理

三种访问方式，后面两种本质都是调用的第一种

2、通过ActionContext访问

ActionContext中是通过map<String,Object>存放Servlet原来的request、response、session等对象以及域对象。

servlet中的request域、response域、session域存值的本质是使用map。

ActionContext的生命周期和request对象的一样，所以不建议使用request域，而使用ActionContext.getContext().put(key,value);的方式，

//通过ActionContext访问ServletApi
public String exectue() {
		
	//session——>map
	Map<String, Object> session = ActionContext.getContext().getSession();
	session.put("name", "session");
		
	//applictiong——>map
	Map<String, Object> application = ActionContext.getContext().getApplication();
	application.put("name", "application");
		
	//不推荐使用request——>map
	Map<String, Object> requestScope = (Map<String, Object>) ActionContext.getContext().get("request");
	requestScope.put("name", "request");
		
	//重写了request的setA,getA等方法，改变了request的取值的位置
	ActionContext.getContext().put("name2", "ActionContext");
		
	return "success";
}

3、通过ServletActionContext访问

//通过ServletActionContext访问ServletApi
public String exectue2() {
		
	//原生request
	HttpServletRequest request = ServletActionContext.getRequest();
		
	//先获得request,再获得session
	HttpSession session = request.getSession();
		
	//原生response
	HttpServletResponse response = ServletActionContext.getResponse();
		
	//原生servletContext
	ServletContext servletContext = ServletActionContext.getServletContext();
		
	return "success";
}

4、通过实现接口方式访问

public class AwareApi extends ActionSupport implements ServletRequestAware {

	private HttpServletRequest request;

	public String execute() {
		return SUCCESS;
	}

	@Override
	public void setServletRequest(HttpServletRequest request) {
		// TODO Auto-generated method stub
		this.request = request;
	}

}