在安裝有多個版本jdk的Linux環境中切換jdk版本

參考自:

Oracle Linux : Switching Back To Previous Version of openjdk (Doc ID 2056238.1)

[[email protected] ~]# java -version
java version "1.7.0_79"------------->>>注意此處的1.7版本
OpenJDK Runtime Environment (rhel-2.5.5.4.el6-x86_64 u79-b14)
OpenJDK 64-Bit Server VM (build 24.79-b02, mixed mode)
[[email protected] ~]# which java
/usr/bin/java
[[email protected] ~]# uname -a
Linux localhost.localdomain 2.6.32-573.el6.x86_64 #1 SMP Wed Jul 1 18:23:37 EDT 2015 x86_64 x86_64 x86_64 GNU/Linux
[[email protected] ~]# cat /etc/redhat-release 
Red Hat Enterprise Linux Server release 6.7 (Santiago)
[[email protected] ~]# rpm -qa | grep -i openjdk
java-1.6.0-openjdk-1.6.0.35-1.13.7.1.el6_6.x86_64
java-1.7.0-openjdk-1.7.0.79-2.5.5.4.el6.x86_64
[[email protected] ~]# 
[[email protected] ~]# update-alternatives --config java


There are 2 programs which provide 'java'.


  Selection    Command
-----------------------------------------------
*+ 1           /usr/lib/jvm/jre-1.7.0-openjdk.x86_64/bin/java
   2           /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java


Enter to keep the current selection[+], or type selection number: 2 ----->>敲入2,然後回車
[[email protected] ~]# which java
/usr/bin/java
[[email protected] ~]# java -version
java version "1.6.0_35"------------->>>注意此處的1.6版本
OpenJDK Runtime Environment (IcedTea6 1.13.7) (rhel-1.13.7.1.el6_6-x86_64)
OpenJDK 64-Bit Server VM (build 23.25-b01, mixed mode)
[[email protected] ~]# rpm -qa | grep -i openjdk
java-1.6.0-openjdk-1.6.0.35-1.13.7.1.el6_6.x86_64
java-1.7.0-openjdk-1.7.0.79-2.5.5.4.el6.x86_64
[[email protected] ~]# 
[[email protected] ~]# su - oracle  -------->>>切換到oracle使用者
[[email protected] ~]$ java -version
java version "1.6.0_35"------------->>>注意此處的1.6版本
OpenJDK Runtime Environment (IcedTea6 1.13.7) (rhel-1.13.7.1.el6_6-x86_64)
OpenJDK 64-Bit Server VM (build 23.25-b01, mixed mode)
[[email protected] ~]$