Find where java class is loaded from

Question

Does anyone know how to programmaticly find out where the java classloader actually loads the class from?

I often work on large projects where the classpath gets v

Answer 1

This approach works for both files and jars:

Class clazz = Class.forName(nameOfClassYouWant);

URL resourceUrl = clazz.getResource("/" + clazz.getCanonicalName().replace(".", "/") + ".class");
InputStream classStream = resourceUrl.openStream(); // load the bytecode, if you wish

Answer 2

Assuming that you're working with a class named MyClass, the following should work:

MyClass.class.getClassLoader();

Whether or not you can get the on-disk location of the .class file is dependent on the classloader itself. For example, if you're using something like BCEL, a certain class may not even have an on-disk representation.

Answer 3

getClass().getProtectionDomain().getCodeSource().getLocation();

Answer 4

Here's an example:

package foo;

public class Test
{
    public static void main(String[] args)
    {
        ClassLoader loader = Test.class.getClassLoader();
        System.out.println(loader.getResource("foo/Test.class"));
    }
}

This printed out:

file:/C:/Users/Jon/Test/foo/Test.class

Answer 5

Another way to find out where a class is loaded from (without manipulating the source) is to start the Java VM with the option: -verbose:class