[root@yuteng opt]# echo $JAVA_HOME
/usr/java/default
[root@yuteng opt]# which java
/usr/java/default/bin/java
[root@yuteng opt]# ls -lrt /usr/java/default
lrwxrwxrwx. 1 root root 8 Jul 24 10:37 /usr/java/default -> ./latest
[root@yuteng opt]# ls -lrt /usr/java/default/bin/java
-rwxr-xr-x. 1 10 143 7718 Apr 11  2015 /usr/java/default/bin/java

[root@yuteng java]# ll /usr/java
total 4
lrwxrwxrwx. 1 root root    8 Jul 24 10:37 default -> ./latest
drwxr-xr-x. 8   10  143 4096 Apr 11  2015 jdk1.7.0_79
lrwxrwxrwx. 1 root root   13 Jul 24 10:37 latest -> ./jdk1.7.0_79