hadoop - MapReduce Mrunit 错误

Question

我是 Hadoop 的新手。昨天照着书上的，使用了JUnit作为气象数据的apper单元测试。但是也有一些问题。

这是我的 pom 文件:

<dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-common</artifactId>
        <version>2.9.0</version>
        <scope>provided</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-hdfs</artifactId>
        <version>2.9.0</version>
    </dependency>
    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-core</artifactId>
        <version>1.2.1</version>
    </dependency>
    <dependency>
        <groupId>org.apache.mrunit</groupId>
        <artifactId>mrunit</artifactId>
        <version>1.1.0</version>
        <classifier>hadoop2</classifier>
        <scope>test</scope>
    </dependency>
    <dependency>
        <groupId>org.apache.hadoop</groupId>
        <artifactId>hadoop-minicluster</artifactId>
        <version>2.9.0</version>
        <scope>test</scope>
    </dependency>
  </dependencies>

</project>

这是问题:

java.lang.IncompatibleClassChangeError: Found class org.apache.hadoop.mapreduce.TaskInputOutputContext, but interface was expected

期待并感谢您的回答!

Answer 1

我刚刚发现在Hadoop 2.x中，没有Hadoop-core，所以正确的pom是:

<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-common</artifactId>
    <version>2.9.0</version>
    <scope>provided</scope>
</dependency>
<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-mapreduce-client-core</artifactId>
    <version>2.9.0</version>
</dependency>
<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-hdfs</artifactId>
    <version>2.9.0</version>
</dependency>
<dependency>
    <groupId>org.apache.mrunit</groupId>
    <artifactId>mrunit</artifactId>
    <version>1.1.0</version>
    <classifier>hadoop2</classifier>
    <scope>test</scope>
</dependency>