java如何用配置文件连接数据库

配置文件

driver=com.mysql.cj.jdbc.Driver
jdbcUrl=jdbc:mysql://127.0.0.1:3306/java_test?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=UTC
user=root
password=123456

java代码中对文件进行调用

package peizhi;

import java.io.InputStream;
import java.sql.Connection;
import java.sql.Driver;
import java.sql.DriverManager;
import java.util.Properties;


public class a1 {
	public Connection getConnection() throws Exception{
		String driverClass = null;
		String jdbcUrl = null;
		String user = null;
		String password = null;
		
		InputStream in = getClass().getClassLoader().getResourceAsStream("db.properties");
		//System.out.println(in.available());
		Properties properties = new Properties();
		properties.load(in);
		driverClass = properties.getProperty("driver");
		jdbcUrl = properties.getProperty("jdbcUrl");
		user = properties.getProperty("user");
		password = properties.getProperty("password");
		Class.forName(driverClass);
		System.out.println("driverClass:" + driverClass);
		System.out.println("password:" + password);
		System.out.println("user:" + user);
		
		Connection conn=DriverManager.getConnection(jdbcUrl, user, password);
		return conn;
	}
	public static void main(String[] args) throws Exception{
		 //TODO Auto-generated method stub
		a1 t2 = new a1();
		System.out.println(t2.getConnection());
	}

}

注意

在运行的时候要选择自己对应的那个类[图片]
如下：

选择下面那个。