Java example source code file (ArrayClassTest.java)

This example Java source code file (ArrayClassTest.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

assertionerror, bytearrayoutputstream, management, mbeanserver, net, network, object, objectname, objectoutputstream, privateclassloader, reflection, spyloadermbean, string, test, testmbean, urlclassloader

The ArrayClassTest.java Java example source code

/*
 * Copyright (c) 2004, 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 4974913
 * @summary Test that array classes can be found in signatures always
 * and can be deserialized by the deprecated MBeanServer.deserialize method
 * @author Eamonn McManus
 * @run clean ArrayClassTest
 * @run build ArrayClassTest
 * @run main ArrayClassTest
 */

import java.io.*;
import java.lang.reflect.*;
import java.net.*;
import javax.management.*;
import javax.management.loading.*;

public class ArrayClassTest {
    public static void main(String[] args) throws Exception {
        MBeanServer mbs = MBeanServerFactory.createMBeanServer();

        /* If this test isn't loaded by a URLClassLoader we will get
           a ClassCastException here, which is good because it means
           this test isn't valid.  */
        URLClassLoader testLoader =
            (URLClassLoader) ArrayClassTest.class.getClassLoader();

        // Create an MLet that can load the same class names but
        // will produce different results.
        ClassLoader loader = new SpyLoader(testLoader.getURLs());
        ObjectName loaderName = new ObjectName("test:type=SpyLoader");
        mbs.registerMBean(loader, loaderName);

        ObjectName testName = new ObjectName("test:type=Test");
        mbs.createMBean(Test.class.getName(), testName, loaderName,
                        new Object[1], new String[] {X[].class.getName()});
        ClassLoader checkLoader = mbs.getClassLoaderFor(testName);
        if (checkLoader != loader)
            throw new AssertionError("Wrong loader: " + checkLoader);

        mbs.invoke(testName, "ignore", new Object[1],
                   new String[] {Y[].class.getName()});

        ByteArrayOutputStream bout = new ByteArrayOutputStream();
        ObjectOutputStream oout = new ObjectOutputStream(bout);
        oout.writeObject(new Z[0]);
        oout.close();
        byte[] bytes = bout.toByteArray();
        ObjectInputStream oin = mbs.deserialize(testName, bytes);
        Object zarray = oin.readObject();
        String failed = null;
        if (zarray instanceof Z[])
            failed = "read back a real Z[]";
        else if (!zarray.getClass().getName().equals(Z[].class.getName())) {
            failed = "returned object of wrong type: " +
                zarray.getClass().getName();
        } else if (Array.getLength(zarray) != 0)
            failed = "returned array of wrong size: " + Array.getLength(zarray);
        if (failed != null) {
            System.out.println("TEST FAILED: " + failed);
            System.exit(1);
        }

        System.out.println("Test passed");
    }

    public static interface TestMBean {
        public void ignore(Y[] ignored);
    }

    public static class Test implements TestMBean {
        public Test(X[] ignored) {}
        public void ignore(Y[] ignored) {}
    }

    public static class X {}
    public static class Y {}
    public static class Z implements Serializable {}

    public static interface SpyLoaderMBean {}

    /* We originally had this extend MLet but for some reason that
       stopped the bug from happening.  Some side-effect of registering
       the MLet in the MBean server caused it not to fail when asked
       to load Z[].  */
    public static class SpyLoader extends URLClassLoader
            implements SpyLoaderMBean, PrivateClassLoader {
        public SpyLoader(URL[] urls) {
            // important that the parent classloader be null!
            // otherwise we can pick up classes from the classpath
            super(urls, null);
        }

        /*
        public Class loadClass(String name) throws ClassNotFoundException {
            System.out.println("loadClass: " + name);
            return super.loadClass(name);
        }

        public Class loadClass(String name, boolean resolve)
                throws ClassNotFoundException {
            System.out.println("loadClass: " + name + ", " + resolve);
            return super.loadClass(name, resolve);
        }
        */

        public Class findClass(String name) throws ClassNotFoundException {
            System.out.println("findClass: " + name);
            if (false)
                new Throwable().printStackTrace(System.out);
            Class c = super.findClass(name);
            System.out.println(" -> " + name + " (" + c.getClassLoader() + ")");
            return c;
        }
    }
}