项目案例模板之登录注册的实现

案例演示

案例代码

设计表

pom.xml

 <dependencies>   <dependency>     <groupId>junit</groupId>     <artifactId>junit</artifactId>     <version>4.11</version>     <scope>test</scope>   </dependency>   <dependency>     <groupId>mysql</groupId>     <artifactId>mysql-connector-java</artifactId>     <version>5.0.5</version>   </dependency>   <dependency>     <groupId>javax.servlet</groupId>     <artifactId>javax.servlet-api</artifactId>     <version>3.1.0</version>     <scope>provided</scope>   </dependency>   <dependency>     <groupId>org.junit.jupiter</groupId>     <artifactId>junit-jupiter-api</artifactId>     <version>RELEASE</version>     <scope>compile</scope>   </dependency> </dependencies>

jdbc

JDBCUtils.java

 package jdbc; ? import org.junit.jupiter.api.Test; ? import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; ? public class JDBCUtils {     public static Connection connection;     private static String url="jdbc:mysql://localhost:3306/aaa?useUnicode=true&characterEncoding=utf-8";     private static String username="root";     private static String password="root"; ?     static{         try {             Class.forName("com.mysql.jdbc.Driver");             connection = DriverManager.getConnection(url,username,password); ?         } catch (ClassNotFoundException e) {             e.printStackTrace();         } catch (SQLException e) {             e.printStackTrace();         }     } ?     public static Connection getConnection(){         return connection;     } ?     @Test     public void test(){         Connection connection = JDBCUtils.getConnection();         System.out.println(connection);     } }

entity

User.java

 package entity; ? public class User {     private int id;     private String username;     private String password; ?     public User() {     } ?     public User(int id, String username, String password) {         this.id = id;         this.username = username;         this.password = password;     } ?     @Override     public String toString() {         return "User{" +                 "id=" + id +                 ", username=‘" + username + ‘\‘‘ +                 ", password=‘" + password + ‘\‘‘ +                 ‘}‘;     } ?     public int getId() {         return id;     } ?     public void setId(int id) {         this.id = id;     } ?     public String getUsername() {         return username;     } ?     public void setUsername(String username) {         this.username = username;     } ?     public String getPassword() {         return password;     } ?     public void setPassword(String password) {         this.password = password;     } }

dao

UserDao.java

 package dao; ? import entity.User; import jdbc.JDBCUtils; ? import java.sql.Connection; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; import java.util.ArrayList; import java.util.List; ? public class UserDao {     private Connection connection = JDBCUtils.getConnection();     private PreparedStatement ps; ?     /*     *添加用户     * */     public int add(User user) throws Exception{         String sql = "insert into user(username,password) values(?,?)"; ?             ps=connection.prepareStatement(sql);             ps.setObject(1,user.getUsername());             ps.setObject(2,user.getPassword());             int exe = ps.executeUpdate();             return exe;     }     public int delete(int id) throws SQLException {         String sql = "delete from user where id=?";         ps = connection.prepareStatement(sql); ?         /*          * 删除用户          * */         ps.setObject(1,id);         int exe = ps.executeUpdate();         return exe;     } ?     /*     * 修改用户     * */     public int update(User user) throws SQLException {         String sql = "update user set username=? , password=? where id=?";         ps = connection.prepareStatement(sql);         ps.setObject(1,user.getUsername());         ps.setObject(2,user.getPassword());         ps.setObject(3,user.getId());          return ps.executeUpdate(); ?     } ?     /*     * 查询所有用户     * */     public List<User> findAll() throws SQLException {         String sql = "select * from user";         ps=connection.prepareStatement(sql);         ResultSet rs =ps.executeQuery();         List<User> list = new ArrayList<User>();         while(rs.next()){             //以 Java 编程语言中 int 的形式获取此 ResultSet 对象的当前行中指定列的值。             int id = rs.getInt("id");             String username = rs.getString("username");             String password = rs.getString("password");             User u = new User(id,username,password);             list.add(u); ?         }         return list;     } ? /* * 通过id查询用户 * */     public User findById(int id) throws SQLException {         String sql = "select * from user where id=?";         ps=connection.prepareStatement(sql);         ps.setInt(1,id);         ResultSet rs = ps.executeQuery(); ?         User u = null;         while (rs.next()){             int uid = rs.getInt("id");             String username = rs.getString("username");             String password = rs.getString("password"); ? ?             u = new User(uid,username,password);         } ?         return u;     } ? ?     /*     * 用户登录     * */     public User login(User user) throws SQLException {         String sql = "select * from user where username=? and password=?";         ps = connection.prepareStatement(sql);         ps.setObject(1,user.getUsername());         ps.setObject(2,user.getPassword()); ?         ResultSet rs = ps.executeQuery();         User u = null; ?         while (rs.next()){             int uid = rs.getInt("id");             String username = rs.getString("username");             String password = rs.getString("password");             u = new User(uid,username,password);         } ?         return u;     } }

service

UserService.java

 package service; ? import dao.UserDao; import entity.User; ? import java.sql.SQLException; import java.util.List; ? public class UserService {     private UserDao userDao = new UserDao(); ?     public int add(User user) throws Exception {         return userDao.add(user);     } ?     public int delete(int id) throws SQLException {         return userDao.delete(id);     } ?     public int update(User user) throws SQLException {         return userDao.update(user);     } ?     public List<User> findAll() throws SQLException {         return userDao.findAll(); ?     } ?     public User findByID(int id) throws SQLException {         return userDao.findById(id);     } ?     public User login(User user) throws SQLException {         return userDao.login(user);     } }

servlet

LoginServlet.java

 package servlet; ? import entity.User; import service.UserService; ? import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; import java.sql.SQLException; ? @WebServlet("/login") public class LoginServlet extends HttpServlet { ?     @Override     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {         doPost(req, resp);     } ?     @Override     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {         req.setCharacterEncoding("utf-8");         resp.setCharacterEncoding("utf-8"); ?         //接受请求参数         String username = req.getParameter("username");         String password = req.getParameter("password"); ?         User user = new User();         user.setUsername(username);         user.setPassword(password); ?         //查询数据         UserService us = new UserService();         User u = null; ?         try {             u=us.login(user);             //跳转             if (u==null){                 req.setAttribute("mess","账号或密码错误");                 req.getRequestDispatcher("login.jsp").forward(req,resp);             }else {                 req.getSession().setAttribute("user",u);                 resp.sendRedirect("main.jsp");             }         } catch (SQLException e) {             e.printStackTrace();         } ? ? ? ?     } }

RegServlet.java

 package servlet; ? import dao.UserDao; import entity.User; ? import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import java.io.IOException; @WebServlet("/reg") public class RegServlet extends HttpServlet {     @Override     protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {         doPost(req, resp);     } ?     @Override     protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {         req.setCharacterEncoding("utf-8");         resp.setCharacterEncoding("utf-8"); ?         //接受请求参数         String username = req.getParameter("username");         String password = req.getParameter("password"); ?         User u = new User();         u.setUsername(username);         u.setPassword(password); ?         UserDao dao = new UserDao();         int i = 0; ?         try {             i=dao.add(u);         } catch (Exception e) {             e.printStackTrace();         } ? ?         //跳转         if(i>0){             req.setAttribute("mess","注册成功");             resp.sendRedirect("login.jsp");         }else{             req.setAttribute("mess","注册失败");             req.getRequestDispatcher("regist.jsp").forward(req,resp);         } ? ?     } }

jsp

web.xml

 <!DOCTYPE web-app PUBLIC  "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"  "http://java.sun.com/dtd/web-app_2_3.dtd" > ? <web-app>   <display-name>Archetype Created Web Application</display-name> ?   <welcome-file-list>     <welcome-file>regist.jsp</welcome-file>   </welcome-file-list> </web-app>

regist.jsp

 <%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %> <html> <head>     <title>注册</title> </head> <body> <h1>用户注册</h1> <hr> <form action="reg" method="post">     <p>         用户名：<input type="text" name="username">     </p>     <p>         密码：<input type="text" name="password">     </p>     <p>         <input type="submit" value="注册">     </p> ? </form> ? ${mess} ? </body> </html>

login.jsp

 <%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %> <html> <head>     <title>登录</title> </head> <body> <h1>用户登录</h1> <hr> <form action="login" method="post">     <p>         用户名：<input type="text" name="username">     </p>     <p>         密码：<input type="text" name="password">     </p>     <p>         <input type="submit" value="登录">     </p> ? </form> ? ${mess} ? </body> </html>

main.jsp

 <%--   Created by IntelliJ IDEA.   User: Lenovo   Date: 2019/4/25   Time: 9:11   To change this template use File | Settings | File Templates. --%> ? <%@ page contentType="text/html;charset=UTF-8" language="java" isELIgnored="false" %> <html> <head>     <title>主页</title> </head> <body> <h1>欢迎使用本系统</h1> 当前用户：${sessionScope.user.username} </body> </html>

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原文地址：https://www.cnblogs.com/zyx110/p/11504310.html