实现用户注册与登入功能的案例

实现用户注册与登入功能的案例

LoginAndRegister类

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Calendar;
import java.util.Date;

import utils.JDBCUtil;

public class LoginAndRegister {
    
    
    public static void main(String[] args) {
        Date date = new java.util.Date();
        Calendar calendar = Calendar.getInstance();
        calendar.set(1994, 8, 3);
        
        User user = new User();
        user.setId(2);
        user.setUsername("Jay");
        user.setPassword("123456");
        user.setNickname("Jay");
        user.setGender("女");
        user.setRegistdate(date);
        user.setBirthday(calendar.getTime());
        
        boolean regist = regist(user);
        if (regist) {
            System.out.println("注册成功!");
        } else {
            System.out.println("注册失败!");
        }
        
        boolean login = login("周娟娟", "123");
        if (login) {
            System.out.println("成功登入!");
        } else {
            System.out.println("登入失败!");
        }
    }
    
    /**功能: 登录
     * @param username
     * @param password
     * @return
     */
    public static boolean login(String username,String password) {
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        try {
            connection = JDBCUtil.getConnection();
            
            // 查询用户名和密码是否正确
            String sql = "select * from userInfo where username = ? and password = ? ";
            statement = connection.prepareStatement(sql); // 这里会进行预编译,防止恶意的代码注入
            statement.setString(1, username); // 设置占位符?的值
            statement.setString(2, password); // 设置占位符?的值
            resultSet = statement.executeQuery(); // 执行sql语句
            if(resultSet.next()) {
                return true;
            }
            return false;
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JDBCUtil.release(resultSet, statement, connection);
        }
        return false;
    }
    
    /**功能: 注册
     * @param user
     * @return
     */
    public static boolean regist(User user) {
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        ResultSet isRegist = null;
        PreparedStatement statement2 = null;
        try {
            connection = JDBCUtil.getConnection();
            
            String sql = "insert into userInfo values(?, ?, ?, ?, ?, ?, ?)";
            statement = connection.prepareStatement(sql);
            statement.setInt(1, user.getId());
            statement.setString(2, user.getUsername());
            statement.setString(3, user.getPassword());
            statement.setString(4, user.getNickname());
            statement.setString(5, user.getGender());
            // 向数据库插入日期要转换成数据库的日期格式
            statement.setDate(6, new java.sql.Date(user.getRegistdate().getTime()));
            statement.setDate(7, new java.sql.Date(user.getBirthday().getTime()));
            
            // 查询数据库中是否有该用户名
            String sql2 = "select username from userInfo where username= ?";
            statement2 = connection.prepareStatement(sql2);
            statement2.setString(1, user.getUsername());
            // 判断该用户名是否已被注册
            isRegist = statement2.executeQuery();
            if (isRegist.next()) {
                return false;
            } else {
                int update = statement.executeUpdate();
                if (update > 0) {
                    return true;
                } else {
                    return false;
                }
            }
        } catch (SQLException e) {
            e.printStackTrace();
        } finally {
            JDBCUtil.release(resultSet, statement, connection);
            JDBCUtil.release(isRegist);
            JDBCUtil.release(statement2);
        }
        return false;
    }
    
}

实现数据库连接和关闭资源的工具类

import java.io.IOException;
import java.io.InputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Properties;

public class JDBCUtil {
    
    private static final String DRIVER = "driver";
    private static final String URL = "url";
    private static final String USERNAME = "username";
    private static final String PASSWORD = "password";
    private static Properties properties = null;
    
    static {
        try {
            // 加载资源文件
            properties = new Properties();
            ClassLoader classLoader = JDBCUtil.class.getClassLoader();
            InputStream is = classLoader.getResourceAsStream("db.properties");
            properties.load(is);
            
            // 加载驱动
            String driver = properties.getProperty(DRIVER);
            Class.forName(driver);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    
    /**功能: 连接数据库
     * @return
     */
    public static Connection getConnection() {
        String url = properties.getProperty(URL);
        String username = properties.getProperty(USERNAME);
        String password = properties.getProperty(PASSWORD);
        Connection connection = null;
        try {
            connection = DriverManager.getConnection(url, username, password);
            return connection;
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return null;
    }
    
    /**功能: 释放 ResultSet, Statement, Connection资源
     * @param resultSet
     * @param statement
     * @param connection
     */
    public static void release(ResultSet resultSet, Statement statement, Connection connection) {
        try {
            if (resultSet != null) {
                resultSet.close();
            }
            if (statement != null) {
                statement.close();
            }
            if (connection != null) {
                connection.close();
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
    
    /**功能: 释放ResultSet资源
     * @param resultSet
     */
    public static void release(ResultSet resultSet) {
        if (resultSet != null) {
            try {
                resultSet.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    
    /**功能: 释放Statement资源
     * @param statement
     */
    public static void release(Statement statement) {
        if (statement != null) {
            try {
                statement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    
    /**功能: 释放Connection资源
     * @param connection
     */
    public static void release(Connection connection) {
        if (connection != null) {
            try {
                connection.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }
    
    /**功能: 释放PreparedStatement资源
     * @param PreparedStatement
     */
    public static void release(PreparedStatement preparedStatement) {
        if (preparedStatement != null) {
            try {
                preparedStatement.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

}