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！
