driver = com.mysql.jdbc.Driver
url = jdbc:mysql://127.0.0.1:3306/db_one
user = root
password = root

package cn.itcast.util;

import java.io.FileReader;
import java.io.IOException;
import java.net.URL;
import java.sql.*;
import java.util.Properties;

public class JDBCUtils {
    //连接数据库地址
    private static String url;
    //用户名
    private static String user;
    //用户密码
    private static String password;
    //数据库版本
    private static String driver;

    /**
     * 调用工具类启动注册
     */
    static {
        try {
            Properties pro = new Properties();
            // 获取此类在src下绝对位置
            ClassLoader classLoader = JDBCUtils.class.getClassLoader();
            // 动态获取src下jdbc.properties的绝对地址
            URL resource = classLoader.getResource("jdbc.properties");
            // 将URL转换成String类型地址
            String path = resource.getPath();
            pro.load(new FileReader(path));
            url = pro.getProperty("url");
            user = pro.getProperty("user");
            password = pro.getProperty("password");
            driver = pro.getProperty("driver");
            try {
                Class.forName(driver);
            } catch (ClassNotFoundException e) {
                e.printStackTrace();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取连接
     *
     * @return 连接对象
     * @throws SQLException sql异常
     */
    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(url, user, password);
    }

    /**
     * 关闭资源
     *
     * @param conn 连接对象
     * @param stmt sql对象
     */
    public static void closeConnection(Connection conn, Statement stmt) {
        if (stmt != null) {
            try {
                stmt.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if (conn != null) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * 关闭资源
     *
     * @param conn 连接对象
     * @param stmt sql对象
     * @param rs   结果集对象
     */
    public static void closeConnection(Connection conn, Statement stmt, ResultSet rs) {
        if (rs != null) {
            try {
                rs.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        closeConnection(conn, stmt);
    }
}