Session 计数例子

import java.io.IOException;
import java.io.PrintWriter;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

/**
 * Servlet implementation class CountServlet
 */
@WebServlet("/CountServlet")
public class CountServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#service(HttpServletRequest request, HttpServletResponse response)
     */
    protected void service(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out=response.getWriter();
        
        HttpSession session =request.getSession();  //获取Session对象
        System.out.println(session.getId());
        
        Integer count =(Integer)session.getAttribute("count"); //绑定数据
        
        if(count==null)
        {
            count=1;
        }
        else{
            count++;
        }
        
        session.setAttribute("count", count);   //获取绑定数据
        out.println("这个是"+count+"次访问");
        out.close();
    }

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

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

}