test/hotspot/jtreg/vmTestbase/vm/share/transform/TransformingClassLoader.java

/*
 * Copyright (c) 2013, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package vm.share.transform;

import vm.share.FileUtils;

public class TransformingClassLoader extends ClassLoader {
    private final AbstractClassFileTransformer transformer;

    protected TransformingClassLoader(ClassLoader parent,
            AbstractClassFileTransformer transformer) {
        super(parent);
        this.transformer = transformer;
    }

    @Override
    protected Class<?> loadClass(String name, boolean resolve)
            throws ClassNotFoundException {
        if (!transformer.shouldBeTransformed(name)) {
            return super.loadClass(name, resolve);
        }
        synchronized (getClassLoadingLock(name)) {
            // First, check if the class has already been loaded
            Class<?> c = findLoadedClass(name);
            if (c == null) {
                try {
                    byte[] bytes = FileUtils.readClass(name);
                    bytes = transformer.transformClass(bytes);
                    c = defineClass(name, bytes, 0, bytes.length);
                } catch (Exception e) {
                    e.printStackTrace();
                    return super.loadClass(name, resolve);
                }
            }
            if (resolve) {
                resolveClass(c);
            }
            return c;
        }
    }
}