【OSX】多个JDK共存时选择要使用的JDK版本

10.5以后的$JAVA_HOME没有被在.bash_profile中设置的话会被默认设置为 /usr/libexec/java_home。

如果一台mac里面安装了多个JDK， 可以通过/usr/libexec/java_home -V 来查看， 结果如下：

 $ /usr/libexec/java_home -V

 Matching Java Virtual Machines ():

     1.7.0_13, x86_64:"Java SE 7"/Library/Java/JavaVirtualMachines/jdk1..0_13.jdk/Contents/Home

     1.6.0_65-b14-, x86_64:"Java SE 6"/System/Library/Java/JavaVirtualMachines/1.6..jdk/Contents/Home

     1.6.0_65-b14-, i386:"Java SE 6"/System/Library/Java/JavaVirtualMachines/1.6..jdk/Contents/Home

 /Library/Java/JavaVirtualMachines/jdk1..0_13.jdk/Contents/Home

最后一行实际上反映的是系统默认使用的JAVA_HOME路径， 也就是执行/usr/libexec/java_home得到的路径。

如果想使用JDK1.6怎么办？

请在.bash_profile中添加

 JAVA_HOME=$(/usr/libexec/java_home -v 1.6)

 export PATH=$PATH:$JAVA_HOME

 export JAVA_HOME

这样在bash下默认使用的就是JDK 1.6了

 $ java -version

 java version "1.6.0_65"

 Java(TM) SE Runtime Environment (build 1.6.0_65-b14--11M4609)

 Java HotSpot(TM) -Bit Server VM (build 20.65-b04-, mixed mode)

另外要注意的一个地方是， 有些App是直接使用:

 $ pwd
 /System/Library/Frameworks/JavaVM.framework/Versions
 $ ls -l
 total
 lrwxr-xr-x   root  wheel    Feb  : 1.4 -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.4. -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.5 -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.5. -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.6 -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.6. -> CurrentJDK
 drwxr-xr-x   root  wheel   Feb  : A
 lrwxr-xr-x   root  wheel     Feb  : Current -> A
 lrwxr-xr-x   root  wheel    Feb  : CurrentJDK -> /System/Library/Java/JavaVirtualMachines/1.6..jdk/Contents
 $ 

CurrentJDK来定位JDK路径的。一般如果JDK1.6是后安装的就会看到CurrentJDK为1.6。

要改的话：

 $ ls -l
 total
 lrwxr-xr-x   root  wheel    Feb  : 1.4 -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.4. -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.5 -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.5. -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.6 -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.6. -> CurrentJDK
 drwxr-xr-x   root  wheel   Feb  : A
 lrwxr-xr-x   root  wheel     Feb  : Current -> A
 lrwxr-xr-x   root  wheel    Feb  : CurrentJDK -> /System/Library/Java/JavaVirtualMachines/1.6..jdk/Contents
 $ sudo rm CurrentJDK
 Password:
 $ ln -s /Library/Java/
 ln: ./: File exists
 $ ls -l
 total
 lrwxr-xr-x   root  wheel    Feb  : 1.4 -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.4. -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.5 -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.5. -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.6 -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.6. -> CurrentJDK
 drwxr-xr-x   root  wheel   Feb  : A
 lrwxr-xr-x   root  wheel     Feb  : Current -> A
 $ ln -s /Library/Java/JavaVirtualMachines/jdk1..0_13.jdk/Contents CurrentJDK
 $ ls -l
 total
 lrwxr-xr-x   root  wheel    Feb  : 1.4 -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.4. -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.5 -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.5. -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.6 -> CurrentJDK
 lrwxr-xr-x   root  wheel    Feb  : 1.6. -> CurrentJDK
 drwxr-xr-x   root  wheel   Feb  : A
 lrwxr-xr-x   root  wheel     Feb  : Current -> A
 lrwxr-xr-x   root  wheel    Feb  : CurrentJDK -> /Library/Java/JavaVirtualMachines/jdk1..0_13.jdk/Contents
 $