Servlet----------用servlet写一个“网站访问量统计“的小案例

package cn.example;

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

import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
/**
 * 网站访问量统计小案例
 * @author LZC
 */
public class CallCount extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        /*
         *1、获取ServletContext对象
         *2、从ServletContext对象中获取名为count的属性用来保存访问量
         *3、如果存在，则保存回去
         *4、如果不存在，说明是第一次访问，向ServletContext中保存名为count的属性，值 为1
         */
        response.setCharacterEncoding("GBK");
        ServletContext application =this.getServletContext();
        Integer count = (Integer) application.getAttribute("count");
        if(count==null){
            application.setAttribute("count", 1);
        }else{
            application.setAttribute("count", count+1);
        }
        
         // 向浏览器输出，需要使用响应请求
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println("<h2>您一共访问了 "+count+" 次</h2>");
    }
}