org.apache.hadoop.util.PlatformName //cgywin下Hadoop-0.21.0 错误问题_could not find the main class: org.apache.hadoop.u-优快云博客

本文详细介绍了在Windows 7专业版32位环境下配置并使用Hadoop-0.21.0的步骤，包括解决namenode创建HDFS时遇到的警告和错误问题，以及通过修改配置文件解决NoClassDefFoundError错误。同时提供了具体代码示例和解决方法。

windows 7 专业版 32位 cgywin下Hadoop-0.21.0 错误问题

格式化管理者，即namenode，创建HDFS

执行命令

$ bin/hadoop namenode -format

$ bin/hadoop namenode -format
cygwin warning:
  MS-DOS style path detected: C:\cygwin\hadoop\/build/native
  Preferred POSIX equivalent is: /hadoop/build/native
  CYGWIN environment variable option "nodosfilewarning" turns off this warning.
  Consult the user's guide for more details about POSIX paths:
    http://cygwin.com/cygwin-ug-net/using.html#using-pathnames
Exception in thread "Main Thread" java.lang.NoClassDefFoundError: org/apache/hadoop/util/PlatformName
Caused by: java.lang.ClassNotFoundException: org.apache.hadoop.util.PlatformName
        at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
Could not find the main class: org.apache.hadoop.util.PlatformName.  Program will exit.
DEPRECATED: Use of this script to execute hdfs command is deprecated.
Instead use the hdfs command for it.

Exception in thread "Main Thread" java.lang.NoClassDefFoundError: org/apache/hadoop/util/PlatformName
Caused by: java.lang.ClassNotFoundException: org.apache.hadoop.util.PlatformName
        at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
Could not find the main class: org.apache.hadoop.util.PlatformName.  Program will exit.

解决方法:

只需要将${HADOOP_HOME}/bin/hadoop-config.sh文件中的第190行的一下的内容
JAVA_PLATFORM=`CLASSPATH=${CLASSPATH} ${JAVA} -Xmx32m ${HADOOP_JAVA_PLATFORM_OPTS} org.apache.hadoop.util.PlatformName | sed -e "s/ /_/g"`
改成
JAVA_PLATFORM=`CLASSPATH=${CLASSPATH} ${JAVA} -Xmx32m -classpath ${HADOOP_COMMON_HOME}/hadoop-common-0.21.0.jar org.apache.hadoop.util.PlatformName | sed -e "s/ /_/g"`

参考： http://blog.youkuaiyun.com/wf1982/article/details/6283618