关于session的一点小疑问。

package listener;

import javax.servlet.ServletContextEvent;
import javax.servlet.ServletContextListener;
import javax.servlet.ServletRequestEvent;
import javax.servlet.ServletRequestListener;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

public class WebListener implements ServletContextListener,HttpSessionListener,ServletRequestListener{

  @Override
  public void contextDestroyed(ServletContextEvent sce) {
    // TODO Auto-generated method stub
    System.out.println("ServletContext 已销毁");
  }

  @Override
  public void contextInitialized(ServletContextEvent sce) {
    // TODO Auto-generated method stub
    System.out.println("ServletContext 已初始化");
  }

  @Override
  public void sessionCreated(HttpSessionEvent arg0) {
    // TODO Auto-generated method stub
    System.out.println("Session已创建,ID: "+  arg0.getSession().getId());
  }

  @Override
  public void sessionDestroyed(HttpSessionEvent arg0) {
    // TODO Auto-generated method stub
    System.out.println("Session已销毁");
  }

  @Override
  public void requestDestroyed(ServletRequestEvent sre) {
    // TODO Auto-generated method stub
    System.out.println("HttpServeltRequest 已销毁");
  }

  @Override
  public void requestInitialized(ServletRequestEvent sre) {
    HttpServletRequest req = (HttpServletRequest)sre.getServletRequest();
    // TODO Auto-generated method stub
    System.out.println("HttpServeltRequest 已创建 uri:  " + req.getRequestURI());
  }
  
  

}

package listener;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

/**
 * Servlet implementation class HelloServlet
 */
@WebServlet("/hello")
public class HelloServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    /**
     * @see HttpServlet#HttpServlet()
     */
    public HelloServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

	/**
	 * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		response.getWriter().println("hello world<br>" );
		request.getServletContext().setAttribute("context", "contextatt");
		request.getSession().setAttribute("session", "sessionatt");
		request.setAttribute("request", "requestatt");
		response.getWriter().println(request.getSession().getId());
	}

	/**
	 * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
	 */
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		// TODO Auto-generated method stub
		doGet(request, response);
	}

}

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://xmlns.jcp.org/xml/ns/javaee" xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_3_1.xsd" id="WebApp_ID" version="3.1">
  <display-name>listener-interface</display-name>
  <welcome-file-list>
    <welcome-file>index.html</welcome-file>
    <welcome-file>index.htm</welcome-file>
    <welcome-file>index.jsp</welcome-file>
    <welcome-file>default.html</welcome-file>
    <welcome-file>default.htm</welcome-file>
    <welcome-file>default.jsp</welcome-file>
  </welcome-file-list>
  <listener>
    <listener-class>listener.WebListener</listener-class>
  </listener>
</web-app>

1. 问下是不是如果不在servlet里面进行session的创建，默认是不会建立session这个东西的？ 

2. 为什么我即使重启了服务器，然后同一个网页浏览器不关闭直接刷新，也不会再次触发Session创建，并且在servlet页面还是会打印出和上次一样的session id? 也就是说服务器直接认可了存储在cookie里面的session id么？ 这个是为什么？