package org.apache.maven.surefire.booter;
   
   /*
    * 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.
   */
  
  import java.net.URL;
  import java.net.URLClassLoader;
  import java.util.HashSet;
  import java.util.Set;
  
  /**
   * @noinspection CustomClassloader
   */
  public class IsolatedClassLoader
      extends URLClassLoader
  {
      private final ClassLoader parent = ClassLoader.getSystemClassLoader();
  
      private final Set<URL> urls = new HashSet<URL>();
  
      private final String roleName;
  
      private boolean childDelegation = true;
  
      private static final URL[] EMPTY_URL_ARRAY = new URL[0];
  
      public IsolatedClassLoader( ClassLoader parent, boolean childDelegation, String roleName )
      {
          super( EMPTY_URL_ARRAY, parent );
  
          this.childDelegation = childDelegation;
  
          this.roleName = roleName;
      }
  
      public void addURL( URL url )
      {
          // avoid duplicates
          if ( !urls.contains( url ) )
          {
              super.addURL( url );
              urls.add( url );
          }
      }
  
      public synchronized Class loadClass( String name )
          throws ClassNotFoundException
      {
          Class c;
  
          if ( childDelegation )
          {
              c = findLoadedClass( name );
  
              ClassNotFoundException ex = null;
  
              if ( c == null )
              {
                  try
                  {
                      c = findClass( name );
                  }
                  catch ( ClassNotFoundException e )
                  {
                      ex = e;
  
                      if ( parent != null )
                      {
                          c = parent.loadClass( name );
                      }
                  }
              }
  
              if ( c == null )
              {
                  throw ex;
              }
          }
          else
          {
              c = super.loadClass( name );
          }
  
         return c;
     }
 
     public String toString()
     {
         return "IsolatedClassLoader{roleName='" + roleName + "'}";
     }
 }