使用JDBC来连接MySQL数据库，在各个方法中都要添加驱动、建立连接、释放资源等，会造成代码的冗余和复杂，所以将相同部分抽取出来，建立一个JDBCUtil的工具类，从.properties配置文件中读取数据，进行驱动和连接部分的实现，使用时直接调用即可。

package com.thoughtworks.Util;

import java.io.FileReader;
import java.io.IOException;
import java.net.URL;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.Objects;
import java.util.Properties;

public class JDBCUtil {
    private static String URL;
    private static String USER;
    private static String PASSWORD;
    private static String DRIVER;
    static{
        //读取资源文件，获取相应的值
        try {
            //1.创建Properties集合类
            Properties prop = new Properties();
            //获取src路径下的文件的方式---->ClassLoader类加载器
            URL pathURL = JDBCUtil.class.getClassLoader().getResource("jdbc.properties");
            String path = Objects.requireNonNull(pathURL).getPath();
            //2.加载文件
            prop.load(new FileReader(path));
            //3.获取数据、赋值
            URL = prop.getProperty("url");
            USER = prop.getProperty("user");
            PASSWORD = prop.getProperty("password");
            DRIVER = prop.getProperty("driver");
            //注册驱动
            Class.forName(DRIVER);
        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }
    }

    public static Connection getConnection() throws SQLException {
        return DriverManager.getConnection(URL, USER, PASSWORD);
    }

    public static void releaseSource(Statement stmt, Connection conn) {
        if(null != stmt) {
            try {
                stmt.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        if(null != conn) {
            try {
                conn.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
    }

    public static void releaseSource(ResultSet res, Statement stmt, Connection conn) {
        if(null != res) {
            try {
                res.close();
            } catch (SQLException e) {
                e.printStackTrace();
            }
        }
        releaseSource(stmt,conn);
    }
}