Java example source code file (Test5102804.java)

This example Java source code file (Test5102804.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

bean, bean_name, beaninfo, class, classnotfoundexception, error, example, introspectionexception, javabean, loader, net, network, override, propertydescriptor, reference, string, test5102804, wrong

The Test5102804.java Java example source code

/*
 * Copyright (c) 2010, 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.
 */

/*
 * @test
 * @bug 5102804
 * @summary Tests memory leak
 * @author Sergey Malenkov
 * @run main/othervm -ms16m -mx16m Test5102804
 */

import java.beans.BeanInfo;
import java.beans.IntrospectionException;
import java.beans.Introspector;
import java.beans.PropertyDescriptor;
import java.beans.SimpleBeanInfo;
import java.lang.ref.Reference;
import java.lang.ref.WeakReference;
import java.net.URL;
import java.net.URLClassLoader;

public class Test5102804 {
    private static final String BEAN_NAME = "Test5102804$Example";
    private static final String BEAN_INFO_NAME = BEAN_NAME + "BeanInfo";

    public static void main(String[] args) {
        if (!isCollectible(getReference()))
            throw new Error("Reference is not collected");
    }

    private static Reference getReference() {
        try {
            ClassLoader loader = new Loader();
            Class type = Class.forName(BEAN_NAME, true, loader);
            if (!type.getClassLoader().equals(loader)) {
                throw new Error("Wrong class loader");
            }
            BeanInfo info = Introspector.getBeanInfo(type);
            if (0 != info.getDefaultPropertyIndex()) {
                throw new Error("Wrong bean info found");
            }
            return new WeakReference<Class>(type);
        }
        catch (IntrospectionException exception) {
            throw new Error("Introspection Error", exception);
        }
        catch (ClassNotFoundException exception) {
            throw new Error("Class Not Found", exception);
        }
    }

    private static boolean isCollectible(Reference reference) {
        int[] array = new int[10];
        while (true) {
            try {
                array = new int[array.length + array.length / 3];
            }
            catch (OutOfMemoryError error) {
                return null == reference.get();
            }
        }
    }

    /**
     * Custom class loader to load the Example class by itself.
     * Could also load it from a different code source, but this is easier to set up.
     */
    private static final class Loader extends URLClassLoader {
        Loader() {
            super(new URL[] {
                    Test5102804.class.getProtectionDomain().getCodeSource().getLocation()
            });
        }

        @Override
        protected Class loadClass(String name, boolean resolve) throws ClassNotFoundException {
            Class c = findLoadedClass(name);
            if (c == null) {
                if (BEAN_NAME.equals(name) || BEAN_INFO_NAME.equals(name)) {
                    c = findClass(name);
                }
                else try {
                    c = getParent().loadClass(name);
                }
                catch (ClassNotFoundException exception) {
                    c = findClass(name);
                }
            }
            if (resolve) {
                resolveClass(c);
            }
            return c;
        }
    }

    /**
     * A simple bean to load from the Loader class, not main class loader.
     */
    public static final class Example {
        private int value;

        public int getValue() {
            return value;
        }

        public void setValue(int value) {
            this.value = value;
        }
    }

    /**
     * The BeanInfo for the Example class.
     * It is also loaded from the Loader class.
     */
    public static final class ExampleBeanInfo extends SimpleBeanInfo {
        @Override
        public int getDefaultPropertyIndex() {
            return 0;
        }

        @Override
        public PropertyDescriptor[] getPropertyDescriptors() {
            try {
                return new PropertyDescriptor[] {
                        new PropertyDescriptor("value", Class.forName(BEAN_NAME))
                };
            }
            catch (ClassNotFoundException exception) {
                return null;
            }
            catch (IntrospectionException exception) {
                return null;
            }
        }
    }
}