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javajarclassclassloader

Determine which JAR file a class is from

I am not in front of an IDE right now, just looking at the API specs.

CodeSource src = MyClass.class.getProtectionDomain().getCodeSource();
if (src != null) {
    URL jar = src.getLocation();
}

I want to determine which JAR file a class is from. Is this the way to do it?

Solution

  • Yes. It works for all classes except classes loaded by bootstrap classloader. The other way to determine is:

    Class klass = String.class;
URL location = klass.getResource('/' + klass.getName().replace('.', '/') + ".class");

    As notnoop pointed out klass.getResource() method returns the location of the class file itself. For example: 

    jar:file:/jdk/jre/lib/rt.jar!/java/lang/String.class
file:/projects/classes/pkg/MyClass$1.class

    The getProtectionDomain().getCodeSource().getLocation() method returns the location of the jar file or CLASSPATH 

    file:/Users/home/java/libs/ejb3-persistence-1.0.2.GA.jar
file:/projects/classes