java在不同目录运行统一文件问题

[牛逼飞飞]

我是从hbase启动的一个错误搞到这个问题的。
[root@chenlong hbase]# pwd
/usr/local/hbase
[root@chenlong hbase]# ./bin/start-hbase.sh
/usr/local/hbase/conf
Error: Could not find or load main class org.apache.hadoop.hbase.util.HBaseConfTool

Error: Could not find or load main class org.apache.hadoop.hbase.zookeeper.ZKServerTool
starting master, logging to /usr/local/hbase/logs/hbase-root-master-chenlong.out
Error: Could not find or load main class org.apache.hadoop.hbase.master.HMaster
starting regionserver, logging to /usr/local/hbase/logs/hbase-root-1-regionserver-chenlong.out
Error: Could not find or load main class org.apache.hadoop.hbase.regionserver.HRegionServer
文件就存在
[root@chenlong hbase]# find / -name HBaseConfTool.java
/usr/local/hbase/hbase-server/src/main/java/org/apache/hadoop/hbase/util/HBaseConfTool.java

然后发现。。。
[root@chenlong ~]# cd
[root@chenlong ~]# javac Test.java
[root@chenlong ~]# java Test
hello world
换了个目录
[root@chenlong ~]# cd /
[root@chenlong /]# javac ~/Test.java
[root@chenlong /]# java ~/Test
Error: Could not find or load main class .root.Test
这是为什么？
[root@chenlong /]# java -version
java version "1.8.0_20"
Java(TM) SE Runtime Environment (build 1.8.0_20-b26)
Java HotSpot(TM) 64-Bit Server VM (build 25.20-b23, mixed mode)

/etc/profile 环境变量设置
export HBASE_HOME=/usr/local/hbase
export JAVA_HOME=/usr/local/jdk
export JRE_HOME=/usr/local/jdk/jre
export PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$HBASE_HOME:$PATH
export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JRE_HOME/lib