mac中使用java-home来查找安装的jdk，更改JAVA_HOME

$ /usr/libexec/java_home  -V
Matching Java Virtual Machines (3):
    1.7.0_09, x86_64: "Java SE 7" /Library/Java/JavaVirtualMachines/jdk1.7.0_09.jdk/Contents/Home
    1.6.0_45-b06-451, x86_64: "Java SE 6" /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
    1.6.0_45-b06-451, i386: "Java SE 6" /System/Library/Java/JavaVirtualMachines/1.6.0.jdk/Contents/Home
 
/Library/Java/JavaVirtualMachines/jdk1.7.0_09.jdk/Contents/Home