MapReduce Mrunit错误

Question

我是Hadoop的新手。昨天我遵循了这本书，并使用JUnit作为气象数据的单元测试。但是有一些问题。

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：找到的类   org.apache.hadoop.mapreduce.TaskInputOutputContext，但接口为   预期的

期待并感谢您的答复！

Answer 1

尝试添加其他jar版本。
我将export default class Row extends Component { constructor(props) { super(props); // icons to listview (arrow icon) this.icons = { up: require("../../assets/ic_play_circle_down.png"), down: require("../../assets/ic_play_circle_up.png") }; this.state = { title: props.title, // getting screen size (width and height) let: ({ width, height } = Dimensions.get("window")), // collapsed check the listview expanded or not if it is true: list view not expanded collapsed: true, isApproved: false, comment: "dummy comment" }; } acceptApproval = () => { this.setState({ isApproved: true }); console.log("Approved TICK " + this.state.isApproved); this.verifyApprovals(); }; regectApproval = () => { this.setState({ isApproved: false }); console.log("Approved" + this.state.isApproved); this.verifyApprovals(); }; 更改为mrunit-1.1.0.jar 老罐子： mrunit-0.9.0-incubating-hadoop2.jar新JAR：-

public interface Mapper<K1, V1, K2, V2> extends JobConfigurable, Closeable { }

我只是将jar从hadoop1更改为hadoop2，然后所有我的单元测试用例都成功运行了。 https://issues.apache.org/jira/browse/MRUNIT-156

 public class Mapper<KEYIN, VALUEIN, KEYOUT, VALUEOUT> {} 

Answer 2

我刚刚发现，在Hadoop 2.x中，没有Hadoop核心，因此正确的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>