/*

 * Copyright (c) 2003, 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 nsk.share;

import java.io.*;

/**

 * The <code>CustomClassLoader</code> class is used in <code>ClassUnloader</code>.

 *

 * <p>This class loader can load classes and notify <code>ClassUnloader</code>

 * about own finalization to make sure that all loaded classes have been unloaded.

 *

 * <p>By default this class loader loads class from .class file located in directory

 * specified with <code>setClassPath()</code> method. To use any other technique

 * of class loading one should implement derived class, which would override

 * <code>findClass</code> method.

 *

 * @see nsk.share.ClassUnloader

 *

 * @see #setClassPath(String)

 * @see #findClass(String)

 */

public class CustomClassLoader extends ClassLoader {

    private ClassUnloader classUnloader;

    protected String classPath;

    /**

     * Initializes a newly created <code>CustomClassloader</code> object

     * not yet linked with any <code>ClassUnloader</code> object.

     *

     */

    public CustomClassLoader() {

        super(CustomClassLoader.class.getClassLoader());

        this.classUnloader = null;

    }

    /**

     * Initializes a newly created <code>CustomClassloader</code> object

     * linked with specified <code>ClassUnloader</code> object.

     *

     * @param classUnloader an instance of <code>ClassUnloader</code>

     */

    public CustomClassLoader(ClassUnloader classUnloader) {

        super(CustomClassLoader.class.getClassLoader());

        this.classUnloader = classUnloader;

    }

    /**

     * Links this class loader with specified <code>ClassUnloader</code> object.

     *

     * @param classUnloader an instance of <code>ClassUnloader</code>

     */

    public void setClassUnloader(ClassUnloader classUnloader) {

        this.classUnloader = classUnloader;

    }

    /**

     * Specifies path to .class file location.

     *

     * @param classPath a path to .class file location

     */

    public void setClassPath(String classPath) {

        this.classPath = classPath;

    }

    /**

     * Finds and loads class for specified class name.

     * This method loads class from .class file located in a directory

     * previously specified by <code>setClassPath()</code>.

     *

     * @param name The name of the class.

     *

     * @throws ClassNotFoundException if no .class file found

     *          for specified class name

     *

     * @see #setClassPath(String)

     */

    protected synchronized Class findClass(String name) throws ClassNotFoundException {

        java.nio.file.Path path = ClassFileFinder.findClassFile(name, classPath);

        if (path == null) {

            throw new ClassNotFoundException(name);

        }

        String classFileName = path.toString();

        FileInputStream in;

        try {

            in = new FileInputStream(classFileName);

            if (in == null) {

                throw new ClassNotFoundException(classFileName);

            }

        } catch (FileNotFoundException e) {

            throw new ClassNotFoundException(classFileName, e);

        }

        int len;

        byte data[];

        try {

            len = in.available();

            data = new byte[len];

            for (int total = 0; total < data.length; ) {

                total += in.read(data, total, data.length - total);

            }

        } catch (IOException e) {

            throw new ClassNotFoundException(classFileName, e);

        } finally {

            try {

                in.close();

            } catch (IOException e) {

                throw new ClassNotFoundException(classFileName, e);

            }

        }

        return defineClass(name, data, 0, data.length);

    }

    /**

     * Notifies <code>ClassUnloader</code> about finalization.

     */

    protected void finalize() throws Throwable {

        // notify ClassUnloader about finalization

        if (classUnloader != null) {

            classUnloader.finalized = true;

        }

        super.finalize();

    }

}