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).
這是因為項目剛創建成功，還沒有配置數據源，所以無法指定url
可以再啟動類的注解@SpringBootApplication()中加上參數
如下即可：
@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
這樣就不會報錯了！