摘自：https://www.cnblogs.com/WeiMJ/p/9180159.html
Description:
Failed to configure a DataSource: 'url' attribute is not specified and no embedded datasource could be configured.
Reason: Failed to determine a suitable driver class
Action:
Consider the following:
If you want an embedded database (H2, HSQL or Derby), please put it on the classpath.
If you have database settings to be loaded from a particular profile you may need to activate it (no profiles are currently active).
这是因为项目刚创建成功，还没有配置数据源，所以无法指定url
可以再启动类的注解@SpringBootApplication()中加上参数
如下即可：
@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
这样就不会报错了！