我正试图将mysql数据库加载到spring boot应用程序中，但当我启动应用程序时，会收到以下错误消息：
2018-07-17 13:46:31.426 WARN 2120 --- [ restartedMain] o.s.b.a.orm.jpa.DatabaseLookup : Unable to determine jdbc url from datasource org.springframework.jdbc.support.MetaDataAccessException: Could not get Connection for extracting meta-data; nested exception is org.springframework.jdbc.CannotGetJdbcConnectionException: Failed to obtain JDBC Connection: 'url' not set 虽然我在中设置了url属性 application.properties : spring.datasource.url=jdbc:mysql://localhost:3306/mydatabase 有人能帮我弄清楚这个吗？
编辑：这是我的主要课程：

package com.randomsoft.checkoff;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration;

@SpringBootApplication
@EnableAutoConfiguration(exclude = {DataSourceAutoConfiguration.class})
public class CheckoffApplication {

public static void main(String[] args) {
    SpringApplication.run(CheckoffApplication.class, args);
}
}