今天写了个测试类，运行时出错了，错误如下：
java.lang.SecurityException: class "junit.framework.JUnit4TestCaseFacade"'s signer information does not match signer information of other classes in the same package at java.lang.ClassLoader.checkCerts(Unknown Source) at java.lang.ClassLoader.preDefineClass(Unknown Source) at java.lang.ClassLoader.defineClass(Unknown Source) at java.security.SecureClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.defineClass(Unknown Source) at java.net.URLClassLoader.access$100(Unknown Source) at java.net.URLClassLoader$1.run(Unknown Source) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClassInternal(Unknown Source) at org.junit.internal.runners.OldTestClassRunner$OldTestClassAdaptingListener.asDescription(OldTestClassRunner.java:41) at org.junit.internal.runners.OldTestClassRunner$OldTestClassAdaptingListener.startTest(OldTestClassRunner.java:31) at junit.framework.TestResult.startTest(TestResult.java:151) at junit.framework.TestResult.run(TestResult.java:103) at junit.framework.TestCase.run(TestCase.java:118) at junit.framework.TestSuite.runTest(TestSuite.java:208) at junit.framework.TestSuite.run(TestSuite.java:203) at org.junit.internal.runners.OldTestClassRunner.run(OldTestClassRunner.java:76) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:38) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)
反复检查，测试类没有写错，于是上网查了下，原来我以前的代码都是在JUnit3下执行的，而这个类在JUnit4下执行所以出错了，在测试类点击右键，
路径Run As-->Open Run Dialog-->Test Runner:JUnit 4改为JUnit3
点击Apply OK！
还有一种解决方案：自己下个JUnit 4包，然后再执行（未验证）
