报错解决：Reason: Failed to determine a suitable driver class

背景：

导入别人的项目，却报错：

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2022-05-06 23:35:15.267 ERROR 12944 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

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APPLICATION FAILED TO START
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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).


Process finished with exit code 1

这是一个常见的问题，如果试了很多都不行，可能是这个原因，以下是没解决前截图：

注意看：

1、 ​​resources​​ 其实只是一个普通的文件夹而已

2、配置文件里， ​​spring.datasource.url​​ 是灰色的，而 ​​spring.datasource.password​​ 却是有颜色的

解决步骤：右击 ​​resources​​ 文件夹，然后选择 ​​Mark Directory as​​ ，然后选择 ​​Resources Root​​ 即可：

修改好之后：

这样就不会报错了！