In IDEA Cnnot resolve symbol 'ConnectPool', the code red, the class name and folder name of squiggly red line

Error Screenshot:

solution:

1. Check if there is a corresponding package, if the package has a corresponding package is loaded into the project path (my mistake did not put the package is loaded into the project path), the two methods as follows
   (1) Click on the package name ----- > right -------> Add as Library.
   
   (2) Reference blog: IDEA: The \ Jar package in lib to the project path .
2. The first step is no problem, it is still useless import error corresponding to the following classes into the package code, place the cursor on the red font Press: Alt + the Enter key combination can be.