The JDK source code is packaged in a src.jar, and should be in the JDK/Home folder. However, some JDK versions in Mac OSX didn’t include the source code or Javadoc.
Try find it :
sudo find / -name src.jar
If you couldn’t find the src.jar, then get it from Apple developer website.
Go https://developer.apple.com/downloads/index.action , sign in with your Apple ID.
Download the “Java for OS X 2013-0* Developer Package“, it contains JDK runtime, source code and Javadoc, install the downloaded *.dmg and follow the wizard guide to finish the installation.
After the installation, the JDK source code should be found in following location :
/Library/Java/JavaVirtualMachines/jdk_version.jdk/Contents/Home/src.jar ##example /Library/Java/JavaVirtualMachines/1.6.0_43-b01-447.jdk/Contents/Home/src.jar