public class DBUtil {
    private static Properties properties;

    static {
        properties = new Properties();
        try {
            properties.load(DBUtil.class.getClassLoader().getResourceAsStream("db.properties"));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static Connection getConnection() throws ClassNotFoundException, SQLException {
        Connection connection;
        Class.forName(getValue("driver"));
        return DriverManager.getConnection(getValue("url"),getValue("user"),getValue("password"));
    }

    private static String getValue(String key) {
        if(properties.containsKey(key)){
            return properties.getProperty(key);
        }else
            throw new KeyNotFoundException("未找到对应的key ："+key);
    }
}

public class KeyNotFoundException extends RuntimeException {
    public KeyNotFoundException() {
        super();
    }

    public KeyNotFoundException(String message) {
        super(message);
    }
}

package util;

import java.io.FileInputStream;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;
import java.util.Properties;

/**
 * @author Shi Jun Yi
 * @version 1.0
 * @date 2020/12/16 15:23
 * 连接数据库
 */
public class DBUtil {

    static int port = 0;
    static String database = null;
    static String url = null;
    static String username = null;
    static String password = null;

    public static Connection getConnection() throws SQLException{

        Properties pro = new Properties();
        try {
            FileInputStream fis = new FileInputStream("D:\\JavaIDEA\\Demo_HuTu\\src\\properties\\dbcpconfig.properties");
            pro.load(fis);
            String driverName = pro.getProperty("driverClassName");
            url = pro.getProperty("url");
            username = pro.getProperty("username");
            password = pro.getProperty("password");
            port = Integer.parseInt(pro.getProperty("port"));
            database = pro.getProperty("database");

            Class.forName(driverName);
            System.out.println("数据库连接成功!！");
        } catch (Exception e) {
            e.printStackTrace();
        }

        //建立链接
        return  DriverManager.getConnection(url, username, password);
    }

}