hadoop - MRUNIT java.lang.IncompatibleClassChangeError

Question

在运行测试用例时，出现此异常

 java.lang.IncompatibleClassChangeError: Found interface org.apache.hadoop.mapreduce.TaskInputOutputContext, but class was expected
    at org.apache.hadoop.mrunit.mapreduce.mock.MockContextWrapper.createCommon(MockContextWrapper.java:53)
    at org.apache.hadoop.mrunit.mapreduce.mock.MockMapContextWrapper.create(MockMapContextWrapper.java:70)
    at org.apache.hadoop.mrunit.mapreduce.mock.MockMapContextWrapper.<init>(MockMapContextWrapper.java:62)
    at org.apache.hadoop.mrunit.mapreduce.MapDriver.run(MapDriver.java:217)
    at org.apache.hadoop.mrunit.MapDriverBase.runTest(MapDriverBase.java:150)
    at org.apache.hadoop.mrunit.TestDriver.runTest(TestDriver.java:137)
    at konnectMR.konnect.mr.MRTestOne.testMapper(MRTestOne.java:44)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.junit.internal.runners.TestMethod.invoke(TestMethod.java:59)
    at org.junit.internal.runners.MethodRoadie.runTestMethod(MethodRoadie.java:98)
    at org.junit.internal.runners.MethodRoadie$2.run(MethodRoadie.java:79)
    at org.junit.internal.runners.MethodRoadie.runBeforesThenTestThenAfters(MethodRoadie.java:87)
    at org.junit.internal.runners.MethodRoadie.runTest(MethodRoadie.java:77)
    at org.junit.internal.runners.MethodRoadie.run(MethodRoadie.java:42)
    at org.junit.internal.runners.JUnit4ClassRunner.invokeTestMethod(JUnit4ClassRunner.java:88)
    at org.junit.internal.runners.JUnit4ClassRunner.runMethods(JUnit4ClassRunner.java:51)
    at org.junit.internal.runners.JUnit4ClassRunner$1.run(JUnit4ClassRunner.java:44)
    at org.junit.internal.runners.ClassRoadie.runUnprotected(ClassRoadie.java:27)
    at org.junit.internal.runners.ClassRoadie.runProtected(ClassRoadie.java:37)
    at org.junit.internal.runners.JUnit4ClassRunner.run(JUnit4ClassRunner.java:42)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:50)
    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)

这是POM的依赖

   <dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.4</version>
</dependency>
<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-common</artifactId>
    <version>2.0.3-alpha</version>
</dependency>
<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-mapreduce-client-core</artifactId>
    <version>2.0.3-alpha</version>
</dependency>
<dependency>
    <groupId>com.google.code.gson</groupId>
    <artifactId>gson</artifactId>
    <version>2.2.4</version>
</dependency>
<dependency>
    <groupId>org.apache.mrunit</groupId>
    <artifactId>mrunit</artifactId>
    <version>0.9.0-incubating</version>
    <classifier>hadoop1</classifier> 
</dependency>
<dependency>
    <groupId>org.apache.mrunit</groupId>
    <artifactId>mrunit</artifactId>
    <version>0.9.0-incubating</version>
    <classifier>hadoop2</classifier>
</dependency>

谁能帮我解决这个错误？

Answer 1

您添加两个“org.apache.mrunit”依赖项。第一个“org.apache.mrunit”处于 Activity 状态。这是hadoop1 api。由于您使用的是hadoop2，因此需要删除“org.apache.mrunit”的第一个依赖项。删除以下内容:

<dependency>
    <groupId>org.apache.mrunit</groupId>
    <artifactId>mrunit</artifactId>
    <version>0.9.0-incubating</version>
    <classifier>hadoop1</classifier> 
</dependency>

考虑到mrunit仅用于单元测试。您可以将第二个依赖项更改为以下内容:

<dependency>
    <groupId>org.apache.mrunit</groupId>
    <artifactId>mrunit</artifactId>
    <version>0.9.0-incubating</version>
    <classifier>hadoop2</classifier>
    <scope>test</scope>
</dependency>