test/dubbo-test-runner/src/main/java/org/apache/dubbo/test/runner/ClassLoaderUtils.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.dubbo.test.runner;

import sun.misc.Unsafe;

import java.lang.reflect.Field;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;

/*
 * from https://gist.github.com/hengyunabc/644f8e84908b7b405c532a51d8e34ba9
 */
public class ClassLoaderUtils {
    @SuppressWarnings({ "restriction", "unchecked" })
    public static URL[] getUrls(ClassLoader classLoader) {
        if (classLoader instanceof URLClassLoader) {
            return ((URLClassLoader) classLoader).getURLs();
        }

        // jdk9
        if (classLoader.getClass().getName().startsWith("jdk.internal.loader.ClassLoaders$")) {
            try {
                Field field = Unsafe.class.getDeclaredField("theUnsafe");
                field.setAccessible(true);
                Unsafe unsafe = (Unsafe) field.get(null);

                // jdk.internal.loader.ClassLoaders.AppClassLoader.ucp
                Field ucpField = classLoader.getClass().getDeclaredField("ucp");
                long ucpFieldOffset = unsafe.objectFieldOffset(ucpField);
                Object ucpObject = unsafe.getObject(classLoader, ucpFieldOffset);

                // jdk.internal.loader.URLClassPath.path
                Field pathField = ucpField.getType().getDeclaredField("path");
                long pathFieldOffset = unsafe.objectFieldOffset(pathField);
                ArrayList<URL> path = (ArrayList<URL>) unsafe.getObject(ucpObject, pathFieldOffset);

                return path.toArray(new URL[path.size()]);
            } catch (Exception e) {
                e.printStackTrace();
                return null;
            }
        }
        return null;
    }
}