HBase扫描的java.lang.NoClassDefFoundError

问题描述

我试图运行MapReduce作业来扫描HBase表。目前我正在使用Cloudera 4.4附带的HBase版本0.94.6。在我的程序中的某个地方，我使用了Scan（），并且正确地导入它：

  import org.apache.hadoop。 hbase.client.Scan; 
  

它编译得很好，我也可以创建一个jar文件。我通过将 hbase classpath 作为-cp选项的值来传递。在运行程序时，我得到以下消息：

 线程main中的异常java.lang.NoClassDefFoundError：org / apache / hadoop / hbase / client / Scan 
  

我使用以下代码运行代码：

  hadoop jar my_program.jar MyJobClass -libjars< list_of_jars> 
  

其中list_of_jars包含/opt/cloudera/parcels/CDH/lib/hbase/hbase.jar。为了仔细检查，我确认了hbase.jar包含Scan。我这样做：

  jar tf /opt/cloudera/parcels/CDH/lib/hbase/hbase.jar 
  

我可以看到这行：

  org / apache / hadoop / hbase / client / Scan.class 
  

in输出。所有看起来都对我好。我不明白为什么说扫描没有定义。我传递了正确的jar文件，它包含了这个类。

任何帮助都是值得赞赏的。

解决方案

设置HADOOP_CLASSPATH变量解决了问题：
$ b $ $ p $ `

I am trying to run a MapReduce job to scan a HBase table. Currently I am using the version 0.94.6 of HBase that comes with Cloudera 4.4. At some point in my program I use Scan(), and I properly import it with:

import org.apache.hadoop.hbase.client.Scan;

It compiles well and I am able to create a jar file too. I do it by passing the hbase classpath as the value for the -cp option. When running the program, I obtain the following message:

Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/hadoop/hbase/client/Scan

I run the code using:

hadoop jar my_program.jar MyJobClass -libjars <list_of_jars>

where list_of_jars contains /opt/cloudera/parcels/CDH/lib/hbase/hbase.jar. Just to double-check, I confirmed that hbase.jar contains Scan. I do it with:

jar tf /opt/cloudera/parcels/CDH/lib/hbase/hbase.jar

And I can see the line:

org/apache/hadoop/hbase/client/Scan.class

in the output. All looks ok to me. I don't understand why is saying that Scan is not defined. I pass the correct jar, and it contains the class.

Any help is appreciated.

解决方案

Setting the HADOOP_CLASSPATH variable fixed the issue:

export HADOOP_CLASSPATH=`/usr/bin/hbase classpath`

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