为什么要我导入commons-logging.jar,使用的不是slf4j+logback吗

java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory

at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.<clinit>(SpringJUnit4ClassRunner.java:96)

at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)

at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)

at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)

at java.lang.reflect.Constructor.newInstance(Constructor.java:408)

at org.junit.internal.builders.AnnotatedBuilder.buildRunner(AnnotatedBuilder.java:104)

at org.junit.internal.builders.AnnotatedBuilder.runnerForClass(AnnotatedBuilder.java:86)

at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)

at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:26)

at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)

at org.junit.internal.requests.ClassRequest.getRunner(ClassRequest.java:33)

at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.createUnfilteredTest(JUnit4TestLoader.java:84)

at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.createTest(JUnit4TestLoader.java:70)

at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.loadTests(JUnit4TestLoader.java:43)

at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:444)

at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)

at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)

at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

Caused by: java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory

at java.net.URLClassLoader$1.run(URLClassLoader.java:372)

at java.net.URLClassLoader$1.run(URLClassLoader.java:361)

at java.security.AccessController.doPrivileged(Native Method)

at java.net.URLClassLoader.findClass(URLClassLoader.java:360)

at java.lang.ClassLoader.loadClass(ClassLoader.java:424)

at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)

at java.lang.ClassLoader.loadClass(ClassLoader.java:357)

... 18 more