IsolatedClassLoader.java

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 ClassLoader parent = ClassLoader.getSystemClassLoader();

    private Set urls = new HashSet();

    private boolean childDelegation = true;

    private static final URL[] EMPTY_URL_ARRAY = new URL[0];

    public IsolatedClassLoader()
    {
        super( EMPTY_URL_ARRAY, null );
    }

    public IsolatedClassLoader( ClassLoader parent, boolean childDelegation )
    {
        super( EMPTY_URL_ARRAY, parent );

        this.childDelegation = childDelegation;
    }

    public IsolatedClassLoader( ClassLoader parent )
    {
        super( EMPTY_URL_ARRAY, parent );
    }

    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;
    }
}