Servlet----------用servlet寫一個“網站訪問量統計“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;
/**
 * 網站訪問量統計小案例
 * @author LZC
 */
public class CallCount extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        /*
         *1、獲取ServletContext對象
         *2、從ServletContext對象中獲取名為count的屬性用來保存訪問量
         *3、如果存在，則保存回去
         *4、如果不存在，說明是第一次訪問，向ServletContext中保存名為count的屬性，值 為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);
        }
        
         // 向瀏覽器輸出，需要使用響應請求
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();
        out.println("<h2>您一共訪問了 "+count+" 次</h2>");
    }
}