content: /*
   * 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.beam.sdk.testing;
  
  import java.io.IOException;
  import java.util.function.Predicate;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.base.Predicates;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Sets;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.io.ByteStreams;
  
  /**
   * A classloader that intercepts loading of specifically named classes. This classloader copies the
   * original classes definition and is useful for testing code which needs to validate usage with
   * multiple classloaders..
   */
  public class InterceptingUrlClassLoader extends ClassLoader {
    private final Predicate<String> test;
  
    public InterceptingUrlClassLoader(final ClassLoader parent, final String... ownedClasses) {
      this(parent, Predicates.in(Sets.newHashSet(ownedClasses))::apply);
    }
  
    public InterceptingUrlClassLoader(final ClassLoader parent, final Predicate<String> test) {
      super(parent);
      this.test = test;
    }
  
    @Override
    public Class<?> loadClass(final String name) throws ClassNotFoundException {
      final Class<?> alreadyLoaded = super.findLoadedClass(name);
      if (alreadyLoaded != null) {
        return alreadyLoaded;
      }
  
      if (name != null && test.test(name)) {
        try {
          final String classAsResource = name.replace('.', '/') + ".class";
          final byte[] classBytes =
              ByteStreams.toByteArray(getParent().getResourceAsStream(classAsResource));
          return defineClass(name, classBytes, 0, classBytes.length);
        } catch (final IOException e) {
          throw new RuntimeException(e);
        }
      }
      return getParent().loadClass(name);
    }
  }
  