1.创建JavaWeb项目，名WebCount
2.修改web.xml，如下：
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" id="WebApp_ID" version="3.0">
<display-name>WebCount1</display-name>
<servlet>
<servlet-name>CounterServlet</servlet-name>
<servlet-class>com.CounterServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>CounterServlet</servlet-name>
<url-pattern>/counter</url-pattern>
</servlet-mapping>
<welcome-file-list>
<welcome-file>counter</welcome-file>
</welcome-file-list>
</web-app>、
3.新建名称为CounterServlet的servlet类，在该类dopost（）方法中实现统计访问数目。
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 CounterServlet
*/
@WebServlet("/CounterServlet")
public class CounterServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
/**
* @see HttpServlet#HttpServlet()
*/
public CounterServlet() {
super();
// TODO Auto-generated constructor stub
}
/**
* @see Servlet#destroy()
*/
public void destroy() {
super.destroy();
}
/**
* @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
this.doPost(request, response);
}
/**
* @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//获得ServletContext对象
ServletContext context=getServletContext();
//从ServletContext中获取计数器对象
Integer count=(Integer) context.getAttribute("counter");
if(count==null){//如果为空，则在ServletContext中设置一个计数器的属性
count=1;
context.setAttribute("counter", count);
}else{
context.setAttribute("counter", count+1);
}
response.setContentType("text/html");//响应正文的MIME类型
response.setCharacterEncoding("UTF-8");//响应的编码格式
PrintWriter out=response.getWriter();
// out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
// out.println("<!DOCTYPE html PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\" \"http://www.w3.org/TR/html4/loose.dtd\">");
// out.println("<HTML>");
out.println("<HEAD><TITLE>统计网站访问次数</TITLE></HEAD>");
out.println("<BODY>");
// out.println("<h2><font color='gray'");
out.println("您是第"+context.getAttribute("counter")+"位访客！");
// out.println("</font>");
// out.println("</h2>");
out.println("</BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
}
4.将项目部署到服务器，启动服务器。结果如下。