Eclipse在我的/ test源文件夹中的类路径上找不到类

Question

I'm trying to write some tests on my Java source code in Eclipse. I created a new Java source directory called /test .

I'm writing JUnit 4 tests on my code. However, when I run my code, I sometimes get really weird errors due to things missing from the classpath evidently:

java.lang.NoClassDefFoundError: org/apache/commons/digester/Digester
    at net.sf.jasperreports.engine.JasperCompileManager.compileReportToStream(JasperCompileManager.java:169)
    at com.smartsports.sswebserver.service.ReportGeneratorServiceImpl.compile(ReportGeneratorServiceImpl.java:94)
    at com.smartsports.sswebserver.service.ReportGeneratorServiceImplTestCase.testCompile(ReportGeneratorServiceImplTestCase.java:75)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:616)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:49)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.lang.ClassNotFoundException: org.apache.commons.digester.Digester
    at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
    ... 27 more

Everything else seems to run and compile great, but tests fail on stuff like this all the time. What am I doing wrong?

Answer 1

Looks like you are using Jasper reports, and since your code directly references that and that Jar file is included in your classpath, it compiles fine. However, Jasper reports appears to depends on the Apache Digester stuff which also needs to be in your classpath. Get the Jar file for the Apache Digester and add it to your classpath.

You will likely hit this with many Jar files as Jasper reports probably depends on a lot of things, so you can either find each one as it fails or find all of the Jars by looking in the Jasper reports distribution and you will probably find a directory that contains all of the required Jars.

If you are doing plugin development, the usual way to accomplish this is to create a plugin that contains Jasper reports and all of its required Jar files (in fact you might find an OSGi bundle (== plugin) out there that has this).

If you are not doing plugin development, then configure your Java Build Path (select the project, right-click and select Build Path -> Configure Build Path) and put the required Jar files in the Libraries tab using one of the many options there.