線程“ main”中的異常java.lang.NoClassDefFoundError：org / apache / hadoop / fs / FSDataInputStrea

Question

我在Cloudera快速入門上還很新，如果對我的解釋不太清楚，請見諒。 無論如何，我正在用Java編寫一個從Hdfs讀取File的代碼。 我構建了一個Maven項目，並在pom.xml中設置了所有依賴項，但是當我嘗試從外殼程序（java -jar jnameofthefile.jar）啟動jar時，出現此錯誤：線程“ main”中的異常java.lang.NoClassDefFoundError：org / apache / hadoop / fs / FSDataInputStrea

這是我的Java代碼：

package com.hdfs_java_api;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.io.IOUtils;



import java.io.InputStream;
import java.io.IOException;
import java.net.URI;

public class HadoopFileSystemCat {

public static void main(String [] args) throws IOException
{
    String uri = "hdfs://quickstart.cloudera:8020/user/hive/warehouse/Orders.csv";
    Configuration conf = new Configuration();
    FileSystem fs = FileSystem.get(URI.create(uri), conf);
    InputStream in = null;

    try {

    in = fs.open(new Path(uri));


    IOUtils.copyBytes(in, System.out, 4096, false);
}finally{
    IOUtils.closeStream(in);
        }
}


}

這是我的pom.xml：

 <project xmlns="http://maven.apache.org/POM/4.0.0" 
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 
 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>com</groupId>
<artifactId>cards</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>

<name>hdfs_java_api</name>
<url>http://maven.apache.org</url>

<properties>
<project.build.sourceEncoding>UTF- 
8</project.build.sourceEncoding>
</properties>

<dependencies>
<dependency>
  <groupId>junit</groupId>
  <artifactId>junit</artifactId>
  <version>3.8.1</version>
  <scope>test</scope>
</dependency>

<dependency>
  <groupId>org.apache.hadoop</groupId>
  <artifactId>hadoop-common</artifactId>
  <version>2.6.0-cdh5.13.0</version>
</dependency>

<dependency>
  <groupId>org.apache.hadoop</groupId>
  <artifactId>hadoop-yarn-common</artifactId>
  <version>2.6.0-cdh5.13.0</version>
</dependency>

<dependency>
  <groupId>org.apache.hadoop</groupId>
  <artifactId>hadoop-mapreduce-client-common</artifactId>
  <version>2.6.0-cdh5.13.0</version>
</dependency>

<dependency>
  <groupId>org.apache.hadoop</groupId>
  <artifactId>hadoop-mapreduce-client-core</artifactId>
  <version>2.6.0-cdh5.13.0</version>
</dependency>
</dependencies>

<repositories>
<repository>
  <id>cloudera</id>
  <name>cloudera</name>
  <url>https://repository.cloudera.com/artifactory/cloudera- 
   repos/</url>
</repository>
</repositories>
<build>
    <plugins>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-jar-plugin</artifactId>
            <configuration>
                <archive>
                    <manifest>

  <mainClass>com.hdfs_java_api.HadoopFileSystemCat</mainClass>
                    </manifest>
                </archive>
            </configuration>
        </plugin>
    </plugins>
</build>

正如我所說的，我是菜鳥，請耐心等待，並盡量保持清晰，謝謝您！

Answer 1

我認為您缺少核心庫

<dependency>
    <groupId>org.apache.hadoop</groupId>
    <artifactId>hadoop-core</artifactId>
    <version>0.20.2</version>
</dependency>

之后，請確保在構建路徑中包括了“ Maven Dependencies”。

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