How can I run test by JUnit4, with more threads?

I have a unit test class, and execute test with Spring JUnit4. All tests execute about 15 minutes, because test runs one by one. Here is my problem. This test we won to execute for continuing integration. After every commit we need to wait this 15 minutes, and this is not acceptable. How can we execute this test with more than one thread, or all tests execute in parallel?