ParentReadResolve.java example

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open-mika-master
// Tags: JDK1.1

// Copyright (C) 2005 Daniel Bonniot <bonniot@users.sf.net>

// This file is part of Mauve.

// Mauve is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2, or (at your option)
// any later version.

// Mauve 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 for more details.

// You should have received a copy of the GNU General Public License
// along with Mauve; see the file COPYING.  If not, write to
// the Free Software Foundation, 59 Temple Place - Suite 330,
// Boston, MA 02111-1307, USA.  */

package gnu.testlet.java.io.Serializable;

import gnu.testlet.TestHarness;
import gnu.testlet.Testlet;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

/**
 * Check when a parent readResolve() method should be used for subclasses.
 *
 * Here is the rationale for this test, based on Sun's javadoc for
 * java.io.Serializable:
 *
 * First, readResolve must be declared with:
 *   ANY-ACCESS-MODIFIER Object readResolve() throws ObjectStreamException;
 * Thus, a non-private readResolve is OK.
 *
 * Second, the rules for invoking readResolve (as for writeReplace) are that
 * it must be called if it would be accessible from the class of the object
 * being deserialized. So, a non-private readSolve method in the parent must
 * be called, but a private one should not be.
 */
public class ParentReadResolve implements Testlet {

  public void test(TestHarness harness)
  {
    try {
      ByteArrayOutputStream outb = new ByteArrayOutputStream();
      ObjectOutputStream outs = new ObjectOutputStream(outb);

      outs.writeObject(MySingleton.instance);
      outs.writeObject(new MyFoo());

      byte[] store = outb.toByteArray();

      ByteArrayInputStream inb = new ByteArrayInputStream(store);
      ObjectInputStream ins = new ObjectInputStream(inb);

      MySingleton x = (MySingleton) ins.readObject();
      harness.check(x == MySingleton.instance);

      MyFoo foo = (MyFoo) ins.readObject();
      harness.check(! foo.resolved);
    }
    catch (Throwable e) {
      harness.debug(e);
    }
  }

  //// Singleton/MySingleton with a non-private readResolve ////

  static abstract class Singleton implements java.io.Serializable
  {
    abstract Singleton getInstance();

    /** NOTE: this readResolve is not private.
     */
    Object readResolve() {
      return getInstance();
    }
  }

  static class MySingleton extends Singleton
  {
    static final MySingleton instance = new MySingleton();

    Singleton getInstance() { return instance; }
  }

  //// Foo/MyFoo with a private readResolve ////

  static abstract class Foo implements java.io.Serializable
  {
    boolean resolved = false;

    /** NOTE: this readResolve is private.
     */
    private Object readResolve() {
      resolved = true;
      return this;
    }
  }

  static class MyFoo extends Foo
  {
  }
}