Servlet创建、声明、映射，利⽤ServletContext统计⼀个⽹站的访问总量。
1）、创建一个servelet
选择要用到的方法
2）、编辑servelet
package com.cont;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletContext;
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 ContServlet
*/
@WebServlet("/ContServlet")
public class ContServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public ContServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//设置字符编码
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
response.setContentType("text/html; charset=utf-8");
//获取全局的共享数据
ServletContext servletContext = this.getServletContext();
//获取计数器count
Integer count = (Integer) servletContext.getAttribute("count");
//如果获取的计算器对象为空 ，说明是第一次访问，并将count，放入servletCount
if( servletContext.getAttribute("count") == null) {
count = 1;
servletContext.setAttribute("count", count);
}else {
//否则就不是第一次访问，将登陆的计数器进行加1的数据更新
servletContext.setAttribute("count", count+1);
}
//将登陆的次数显示在页面上
PrintWriter out =response.getWriter();
out.print("<!DOCTYPE html>\r\n" +
"<html>\r\n" +
"<head>\r\n" +
"<meta charset=\"UTF-8\">\r\n" +
"<title>登陆网页次数统计</title>\r\n" +
"</head>\r\n" +
"<body>");
out.print("<center>");
out.print("<h1>");
out.print("欢迎访问该网站！");
out.print("<h1>");
out.print("<h2>");
out.print("您是第 "+ servletContext.getAttribute("count")+"位访客");
out.print("<h2>");
out.print("</center>");
out.print("</body>\r\n" +
"</html>");
}
/**
* @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);
}
}
3）、配置web.xml
生成web.xml
编辑web.xml
#声明Servlet对象
<servlet>
<servlet-name>ContServlet</servlet-name>
<servlet-class>com.cont</servlet-class>
</servlet>
#映射Servlet对象
<servlet-mapping>
<servlet-name>ContServlet</servlet-name>
<url-pattern>/index.jsp/ContServlet</url-pattern>
</servlet-mapping>
4)、编辑index.jsp
<%@page language="java" contentType="text/html;charset=UTF-8"%>
<html>
<head>
<title>用户统计网站</title>
</head>
<body>
<center>
<a rel="nofollow" href="TestServlet">查看您是第几位访客！</a>
</center>
</body>
</html>
5)、运行servlet
