Servlet監聽統計網站歷史訪問人數
阿新 • • 發佈：2019-02-01
需求：求網站訪問歷史訪問人數
思路：必須有個監聽器：ServletContextListener 檔案儲存 application傳值 利用：contextInitialized和contextDestroyed實現功能
index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="GB18030"%> <% String path = request.getContextPath(); String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/"; %> <% //1.定義一個變數 //String num="0"; //2.取出原來的值(application) Object obj=application.getAttribute("counter"); //3.加一 int intnum=Integer.parseInt(obj.toString()); intnum++; //4.再次存放在application中 application.setAttribute("counter",intnum); %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <base href="<%=basePath%>"> <title>My JSP 'index.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css"> --> </head> <body> 您是本網站的第<span span style="color:red;font-size:34px"><%=intnum %>個使用者</span><br> </body> </html>
CounterListener.java
package cn.wfc.eshop.control; import java.io.BufferedReader; import java.io.FileNotFoundException; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import javax.servlet.ServletContextEvent; import javax.servlet.ServletContextListener; public class CounterListener implements ServletContextListener { @Override public void contextDestroyed(ServletContextEvent arg0) { // TODO Auto-generated method stub System.out.println("--------------銷燬----------------"); String root=arg0.getServletContext().getRealPath("/"); System.out.println("------得到路徑---------"+root); try { FileWriter fw=new FileWriter(root+"WEB-INF\\count.txt"); fw.write(arg0.getServletContext().getAttribute("counter").toString()); fw.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } @Override public void contextInitialized(ServletContextEvent arg0) { // TODO Auto-generated method stub /*String xx= arg0.getServletContext().getInitParameter("x"); String yy= arg0.getServletContext().getInitParameter("y"); System.out.println("------------x和y的值------------"+xx+"---------------"+xx); System.out.println("--------------初始化--------------"); */ System.out.println("-------------讀取檔案了-----------------"); String num=null; String root=arg0.getServletContext().getRealPath("/"); try { //字元流 FileReader fr=new FileReader(root+"WEB-INF\\count.txt"); //緩衝流 BufferedReader br=new BufferedReader(fr); num=br.readLine(); if(num==null){ num="0"; } br.close(); fr.close(); arg0.getServletContext().setAttribute("counter", num); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } }
web.xml
<?xml version="1.0" encoding="UTF-8"?> <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <listener> <listener-class>cn.wfc.eshop.control.CounterListener</listener-class> </listener> <context-param> <param-name>x</param-name> <param-value>1000</param-value> </context-param> <context-param> <param-name>y</param-name> <param-value>100</param-value> </context-param> </web-app>
目錄結構：
