hadoop 配置问题

Question

您好 按照bin/hadoop-daemon.sh start DataNode方法datanode还是不能启动 出错信息如下
Exception in thread "main" java.lang.NoClassDefFoundError: DataNode
Caused by: java.lang.ClassNotFoundException: DataNode
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
Could not find the main class: DataNode. Program will exit.
请问 怎么办、