http://www.leiphone.com/122712-keats-hadoop-isnt-perfect-8-ways-to-replace-hdfs.html
http://www.cnblogs.com/flyoung2008/archive/2011/12/09/2281400.html
http://blog.csdn.net/cybercode/article/details/7084603
http://tessykandy.iteye.com/blog/1453406
http://5282981.blog.51cto.com/5272981/965250
#set java environment
export JAVA_HOME=/usr/lib/jvm/jdk1.6.0_43
export JRE_HOME=/usr/lib/jvm/jdk1.6.0_43/jre
export CLASSPATH=.:$JAVA_HOME/lib:$JRE_HOME/lib:$CLASSPATH
export PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$PATH
如果 java -verion，没有反应，则输入source /etc/profile。则在wj或者root用户下都可以java -version 有反应。
root@ubuntu:/home/wj# hadoop-1.0.4/bin/hadoop fs -ls output
root@ubuntu:/home/wj# hadoop-1.0.4/bin/hadoop fs -cat output/part-00000