NbMarshalledObject.java

/*
 *                 Sun Public License Notice
 * 
 * The contents of this file are subject to the Sun Public License
 * Version 1.0 (the "License"). You may not use this file except in
 * compliance with the License. A copy of the License is available at
 * http://www.sun.com/
 * 
 * The Original Code is NetBeans. The Initial Developer of the Original
 * Code is Sun Microsystems, Inc. Portions Copyright 1997-2000 Sun
 * Microsystems, Inc. All Rights Reserved.
 */

package org.openide.util.io;

import java.io.*;

import org.openide.ErrorManager;

/** Object that holds serialized reference to another object.
* Inspirated by java.rmi.MarshalledObject but modified to
* work with NetBeans and its modules. So no annotations are
* stored with the bytestream and when the object
* is deserialized it is assumed to be produced by the core IDE
* or one of installed modules or it is located in the repository.
*
*
*/
public final class NbMarshalledObject implements Serializable {
    /**
     * @serial Bytes of serialized representation.  If <code>objBytes</code> is
     * <code>null</code> then the object marshalled was a <code>null</code>
     * reference.
     */
    private byte[] objBytes = null;

    /**
     * @serial Stored hash code of contained object. 
     *
     * @see #hashCode
     */
    private int hash;

    /** serial version UID */
    private static final long serialVersionUID = 7842398740921434354L;

    /**
    * Creates a new <code>NbMarshalledObject</code> that contains the
    * serialized representation of the provided object.
    *
    * @param obj the object to be serialized (must be serializable)
    * @exception IOException the object is not serializable
    */
    public NbMarshalledObject(Object obj) throws java.io.IOException {
        if (obj == null) {
            hash = 17;
            return;
        }

        ByteArrayOutputStream bout = new ByteArrayOutputStream();
        ObjectOutputStream out = new NbObjectOutputStream (bout);
        out.writeObject(obj);
        out.flush();
        objBytes = bout.toByteArray();

        int h = 0;
        for (int i = 0; i < objBytes.length; i++) {
            h = 37 * h + objBytes[i];
        }
        hash = h;
    }

    /**
    * Returns a new copy of the contained marshalledobject.
    * The object is deserialized by NbObjectInputStream, so it
    * is assumed that it can be located by core IDE, a module
    * or in the repository.
    *
    * @return a copy of the contained object
    * @exception IOException on any I/O problem
    * @exception ClassNotFoundException if the class of the object cannot be found
    */
    public Object get() throws IOException, ClassNotFoundException {
        if (objBytes == null)	// must have been a null object
            return null;

        ByteArrayInputStream bin = new ByteArrayInputStream(objBytes);
        ObjectInputStream ois = new NbObjectInputStream (bin);
        try {
            return ois.readObject ();
        } catch (RuntimeException weird) {
            // Probably need to know what the bad ser actually was.
            IOException ioe = new IOException(weird.toString());
            StringBuffer buf = new StringBuffer(objBytes.length * 2 + 20);
            buf.append("Bad ser data: "); // NOI18N
            for (int i = 0; i < objBytes.length; i++) {
                int b = objBytes[i];
                if (b < 0) b += 256;
                buf.append(HEX[b / 16]);
                buf.append(HEX[b % 16]);
            }
            ErrorManager.getDefault().annotate(ioe,
		    ErrorManager.UNKNOWN, buf.toString(), null, weird, null);
            throw ioe;
        } finally {
            ois.close ();
        }
    }
    private final static char[] HEX = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'}; // NOI18N

    /**
    * @return a hash code
    */
    public int hashCode() {
        return hash;
    }

    /** Two objects are equal if the hold the same serialized
    * representation.
    *
    * @param obj the object to compare with this <code>MarshalledObject</code>
    * @return <code>true</code> if the objects are serialized into the same bytestreams
     */
    public boolean equals(Object obj) {
        if (obj == this) return true;

        if (obj != null && obj instanceof NbMarshalledObject) {
            NbMarshalledObject other = (NbMarshalledObject) obj;

            return java.util.Arrays.equals (objBytes, other.objBytes);
        } else {
            return false;
        }
    }
}