1.模拟在线人数统计和网站的访问量
2.模拟注册和登陆的功能的实现。
注册，相当于往表中插入数据；登陆，相当于要查询数据和前端页面的数据进行匹配
更新数据
//更新数据public void UpDate(ServletContext sc) {Properties pro = new Properties(); String n;String filePath = "/Users/ruirui/Desktop/count.txt";InputStream in = null;try {in = new FileInputStream(filePath);pro.load(in);} catch (FileNotFoundException e) {e.printStackTrace();} catch (IOException e) {e.printStackTrace();}n = pro.getProperty("count");int a = Integer.parseInt(n) + 1;sc.setAttribute("totalcount", a);pro.setProperty("count", a + "");try {OutputStream os = new FileOutputStream(filePath);pro.store(os, null);} catch (IOException e) {e.printStackTrace();}}
统计在线人数
//在线人数统计public void login(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException, SQLException {String username=req.getParameter("username");String password = req.getParameter("password");TB7 tb7 = mapper.query(username);if (tb7 != null) {if (tb7.getPassword().equals(password)) {resp.setCharacterEncoding("utf-8");PrintWriter out = resp.getWriter();out.print("<script>alert('login Successs'); window.location='index.jsp' </script>");out.flush();out.close(); req.getSession().setAttribute("username", username);//将用户名保存到set集合中names.add(username);//再将names集合保存到application内置对象中req.getServletContext().setAttribute("users", names); //集合大小即为人数多少req.getServletContext().setAttribute("count", names.size());}else {PrintWriter out = resp.getWriter();out.print("<script>alert('password Failed');window.location='index.jsp' </script>");out.flush();out.close();}}else {PrintWriter out = resp.getWriter();out.print("<script>alert('not exist'); window.location='index.jsp' </script>");out.flush();out.close();} }
插入数据
//连接数据库static {try {String resource = "mybatis-config.xml";InputStream is = Resources.getResourceAsStream(resource);SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(is);SqlSession session = sqlSessionFactory.openSession();mapper = session.getMapper(TB7mapper.class);} catch (IOException e) {e.printStackTrace();}//查看是否存在private boolean IsExist(String username, String password) throws SQLException, IOException{TB7 tb7 = mapper.query(username);if (tb7 == null) {return false;}else {return true;}}//插入数据private void register(String username, String password) throws SQLException {try {mapper.Register(username, password);}catch (Exception e) {e.printStackTrace();}}
判断：
@Overrideprotected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException { req.setCharacterEncoding("utf-8");this.UpDate(sc);String str1 = req.getParameter("login");String str2 = req.getParameter("register");String str3 = req.getParameter("logout");if (str1 != null) {try {login(req,resp);} catch (ServletException | IOException | SQLException e) {e.printStackTrace();}}if (str2 != null) {String username = req.getParameter("username");String password = req.getParameter("password");System.out.println(username+password);try {if (!Isexist(username, password)) {this.register(username, password);PrintWriter out = resp.getWriter();out.print("<script>alert('success');window.location='index.jsp' </script>");out.flush();out.close();} else {PrintWriter out = resp.getWriter();out.print("<script>alert('failed');window.location='index.jsp' </script>");out.flush();out.close();}} catch (SQLException e) {e.printStackTrace();}}if (str3 != null) {logout(req,resp);} }
web.xml
<servlet><servlet-name>LOGIN</servlet-name><servlet-class>fir.LOGIN</servlet-class></servlet><servlet-mapping><servlet-name>LOGIN</servlet-name><url-pattern>/LOGIN.do</url-pattern></servlet-mapping>
网页
<%@ page language="java" import="java.util.*" contentType="text/html; charset=UTF-8"pageEncoding="UTF-8" import="java.sql.*"%><%String path = request.getContextPath();String basePath = request.getScheme() + "://"+request.getServerName() + ":"+ request.getServerPort() + path + "/";%><!DOCTYPE html><html><head><base href="/logn/"><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"><title>Insert title here</title></head><body><h1>在线人数为：${count==null? 0:count}</h1><h1>总访问量：${totalcount}</h1>${users}<form action="Main.do" method="get">用户名:<input type="text" name="username">密 码: <input type="password" name="password"><input type="submit" value="登陆" name="login"><input type="submit" value="注册" name="register"><input type="submit" value="注销" name="logout"></form></body></html>
