Navicat Premium 15.0.36激活(Navicat使用快速入门教程)

好的，下面是一个
使用
MySQL
数据库和Servlet的基本登录注册代码示例： 1. 创建一个名为`User`的JavaBean类，包含以下属性和方法： “`java public class User { private String username; private String password; // 构造方法 public User() {} public User(String username, String password) { this.username = username; this.password = password; } // getters 和 setters 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; } } “` 2. 创建一个名为`DBUtil`的
数据库工具类，用于连接
数据库和执行
SQL语句： “`java public class DBUtil { private static final String URL = “jdbc:
mysql://localhost:3306/test?useSSL=false”; private static final String USER = “root”; private static final String PASSWORD = “”; // 获取
数据库连接 public static Connection getConnection() { Connection conn = null; try { Class.forName(“com.
mysql.jdbc.Driver”); conn = DriverManager.getConnection(URL, USER, PASSWORD); } catch (ClassNotFoundException |
SQLException e) { e.printStackTrace(); } return conn; } // 执行查询操作 public static ResultSet executeQuery(String
sql, Object… params) { Connection conn = getConnection(); PreparedStatement pstmt = null; ResultSet rs = null; try { pstmt = conn.prepareStatement(
sql); for (int i = 0; i < params.length; i++) { pstmt.setObject(i + 1, params[i]); } rs = pstmt.executeQuery(); } catch (
SQLException e) { e.printStackTrace(); } return rs; } // 执行更新操作 public static int executeUpdate(String
sql, Object… params) { Connection conn = getConnection(); PreparedStatement pstmt = null; int result = 0; try { pstmt = conn.prepareStatement(
sql); for (int i = 0; i < params.length; i++) { pstmt.setObject(i + 1, params[i]); } result = pstmt.executeUpdate(); } catch (
SQLException e) { e.printStackTrace(); } finally { close(conn, pstmt, null); } return result; } // 关闭资源 public static void close(Connection conn, Statement stmt, ResultSet rs) { try { if (rs != null) { rs.close(); } if (stmt != null) { stmt.close(); } if (conn != null) { conn.close(); } } catch (
SQLException e) { e.printStackTrace(); } } } “` 3. 创建一个名为`UserDao`的数据访问对象类，用于对用户表进行CRUD操作： “`java public class UserDao { // 添加用户 public boolean addUser(User user) { String
sql = “INSERT INTO user(username, password) VALUES(?, ?)”; int result = DBUtil.executeUpdate(
sql, user.getUsername(), user.getPassword()); return result > 0; } // 根据用户名查询用户 public User getUserByUsername(String username) { User user = null; String
sql = “SELECT * FROM user WHERE username=?”; ResultSet rs = DBUtil.executeQuery(
sql, username); try { if (rs.next()) { user = new User(); user.setUsername(rs.getString(“username”)); user.setPassword(rs.getString(“password”)); } } catch (
SQLException e) { e.printStackTrace(); } finally { DBUtil.close(null, null, rs); } return user; } } “` 4. 创建一个名为`LoginServlet`的Servlet类，用于处理用户登录请求： “`java @WebServlet(“/login”) public class LoginServlet extends HttpServlet { private UserDao userDao; @Override public void init() throws ServletException { userDao = new UserDao(); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 获取表单参数 String username = request.getParameter(“username”); String password = request.getParameter(“password”); // 根据用户名查询用户 User user = userDao.getUserByUsername(username); // 验证用户信息 if (user != null && user.getPassword().equals(password)) { // 登录成功，将用户信息保存到Session中 HttpSession session = request.getSession(); session.setAttribute(“user”, user); // 跳转到首页 response.sendRedirect(request.getContextPath() + “/index.jsp”); } else { // 登录失败，返回错误信息 request.setAttribute(“error”, “用户名或密码错误！”); request.getRequestDispatcher(“/login.jsp”).forward(request, response); } } } “` 5. 创建一个名为`RegisterServlet`的Servlet类，用于处理用户注册请求： “`java @WebServlet(“/register”) public class RegisterServlet extends HttpServlet { private UserDao userDao; @Override public void init() throws ServletException { userDao = new UserDao(); } @Override protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // 获取表单参数 String username = request.getParameter(“username”); String password = request.getParameter(“password”); // 封装用户对象 User user = new User(username, password); // 添加用户 boolean result = userDao.addUser(user); // 返回结果 if (result) { request.setAttribute(“message”, “注册成功，请登录！”); request.getRequestDispatcher(“/login.jsp”).forward(request, response); } else { request.setAttribute(“error”, “注册失败，请重试！”); request.getRequestDispatcher(“/register.jsp”).forward(request, response); } } } “` 以上就是一个基本的登录注册代码示例，您可以根据自己的需要进行修改和Navicat Premium 15.0.36激活完善。