您可以右键单击 IntelliJ 项目中的任何目录，选择将目录标记为..."，然后选择源根目录".该director文件夹的颜色将从黄色变为蓝色；IntelliJ 认为所有这些目录都在您的 CLASSPATH 中.

You can right click on any directory in your IntelliJ project, select "Mark Directory As...", and choose "Source Root". That director folder will change color from yellow to blue; IntelliJ considers all those directories to be in your CLASSPATH.