I have tried many combinations and every time I try to add the jars from the lib directory, intelliJ puts the path down as the src directory. I don't know why. When I move the jars to the src/ directory, intelliJ then switches the path to the lib/ directory. I am not sure how to get this to work correctly.
I'm using Intellij IDEA 11.1, trying to add the Selenium Standalone Server 2 JAR to my new Java project, which already has a module. I could not add the .jar to the Project settings Module (as suggested in another answer), but I can add it to either the project or global libraries. This appears to be the best place for it in Intellij IDEA 11.1.
To add the JAR to the project library (individual modules):
Ensure that the project to which you want the JAR added is open, then choose: File > Project Structure > Libraries > [+] (New Project Library) > Java > .../selenium-server-standalone-2.24.1.jar > [Select the module to add the JAR to] > OK
To add the JAR to the global library (so it's used for all projects):
File > Project Structure > Global Libraries > [+] New Global Library > Java > .../selenium-server-standalone-2.24.1.jar > OK
My Selenium project now compiles and runs as expected. (-:
Project structure -> Modules -> -> Add... -> Library -> Java -> Attach Jar Directories... (for IDEA 10). Are you doing the same?
来源：https://stackoverflow.com/questions/5533428/how-to-add-a-jar-to-my-lib-directory-in-intellij-and-have-the-classes-available