即使 jar 包含在类路径中，Eclipse Class 也未找到异常

Question

运行 java 来自 Eclipse 的 Biginsights 服务器上的 mapreduce 程序给出 com.mysql.jdbc.Driver ClassNotFoundException，即使 jars 包含在类路径中

错误：

The system encountered the following error while it was submitting the job:
15/03/26 18:59:29 WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments. Applications should implement Tool for the same.
15/03/26 18:59:29 INFO mapred.JobClient: Cleaning up the staging area hdfs://biginsights-node:9000/user/biadmin/.staging/job_201503261700_0014
Exception in thread "main" java.lang.RuntimeException: java.lang.RuntimeException: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
    at org.apache.hadoop.mapreduce.lib.db.DBInputFormat.setConf(DBInputFormat.java:164)
    at org.apache.hadoop.util.ReflectionUtils.setConf(ReflectionUtils.java:73)
    at org.apache.hadoop.util.ReflectionUtils.newInstance(ReflectionUtils.java:133)
    at org.apache.hadoop.mapred.JobClient.writeNewSplits(JobClient.java:1079)
    at org.apache.hadoop.mapred.JobClient.writeSplits(JobClient.java:1099)
    at org.apache.hadoop.mapred.JobClient.access0(JobClient.java:188)
    at org.apache.hadoop.mapred.JobClient.run(JobClient.java:1010)
    at org.apache.hadoop.mapred.JobClient.run(JobClient.java:963)
    at java.security.AccessController.doPrivileged(AccessController.java:366)
    at javax.security.auth.Subject.doAs(Subject.java:572)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1502)
    at org.apache.hadoop.mapred.JobClient.submitJobInternal(JobClient.java:963)
    at org.apache.hadoop.mapreduce.Job.submit(Job.java:616)
    at org.apache.hadoop.mapreduce.Job.waitForCompletion(Job.java:646)
    at example.DbExportMainClass.main(DbExportMainClass.java:51)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:94)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
    at java.lang.reflect.Method.invoke(Method.java:619)
    at org.apache.hadoop.util.RunJar.main(RunJar.java:212)
Caused by: java.lang.RuntimeException: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
    at org.apache.hadoop.mapreduce.lib.db.DBInputFormat.getConnection(DBInputFormat.java:190)
    at org.apache.hadoop.mapreduce.lib.db.DBInputFormat.setConf(DBInputFormat.java:158)
    ... 19 more
Caused by: java.lang.ClassNotFoundException: com.mysql.jdbc.Driver
    at java.lang.Class.forNameImpl(Native Method)
    at java.lang.Class.forName(Class.java:199)
    at org.apache.hadoop.mapreduce.lib.db.DBConfiguration.getConnection(DBConfiguration.java:148)
    at org.apache.hadoop.mapreduce.lib.db.DBInputFormat.getConnection(DBInputFormat.java:184)
    ... 20 more

尝试了 Whosebug 中针对类似问题的几乎所有建议。

任何建议都会有所帮助。

Answer 1

您需要将 Biginsight lib 文件夹中的 jar 添加到运行作为 Biginsights 应用程序。还要添加 biginsights-env 文件的路径。

默认位置：/opt/ibm/biginsights/IHC/lib

至运行作为 java 应用程序应添加到类路径中。

即使 jar 包含在类路径中，Eclipse Class 也未找到异常

Eclipse Class not found Exception even when jars are included in classpath

java

eclipse

jar

mapreduce

biginsights