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   : 

***************************
APPLICATION FAILED TO START
***************************

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！

其他参考文章：
https://blog.csdn.net/ht_kasi/article/details/82259860?spm=1001.2101.3001.6661.1&utm_medium=distribute.pc_relevant_t0.none-task-blog-2%7Edefault%7ECTRLIST%7ERate-1-82259860-blog-118083303.pc_relevant_antiscanv2&depth_1-utm_source=distribute.pc_relevant_t0.none-task-blog-2%7Edefault%7ECTRLIST%7ERate-1-82259860-blog-118083303.pc_relevant_antiscanv2&utm_relevant_index=1