messageinputstream.java

aglet的部分源码

package com.ibm.aglets;

/*
 * @(#)MessageInputStream.java
 * 
 * IBM Confidential-Restricted
 * 
 * OCO Source Materials
 * 
 * 03L7246 (c) Copyright IBM Corp. 1996, 1998
 * 
 * The source code for this program is not published or otherwise
 * divested of its trade secrets, irrespective of what has been
 * deposited with the U.S. Copyright Office.
 */

import java.io.ObjectInputStream;
import java.io.ObjectStreamClass;
import java.io.OptionalDataException;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.IOException;
import org.aglets.log.*;

/**
 * 
 */

final class MessageInputStream extends ObjectInputStream {
    static private LogCategory logCategory = LogInitializer.getCategory("com.ibm.aglets.MessageImputStream");
	private ResourceManager rm = null;

	/**
	 * Create a new instance of this class.
	 * @param in an input stream containing objests and class data.
	 * @exception IOException if can not read data from the input stream.
	 * @exception StreamCorruptedException if data in the input stream is
	 * invalid.
	 */
	public MessageInputStream(InputStream in, 
							  ResourceManager rm) throws IOException {
		super(in);
		this.rm = rm;
	}
	/**
	 * @param classname class name.
	 * @return the resolved class.
	 * @exception IOException if can not read data from the input stream.
	 * @exception ClassNotFoundException if can not resolve the class.
	 */
	public Class resolveClass(ObjectStreamClass osc) 
			throws IOException, ClassNotFoundException {

		Class cls = (rm == null) ? Class.forName(osc.getName()) 
					: rm.loadClass(osc.getName());

		ClassLoader loader = cls.getClassLoader();

		if (loader == null ||!(loader instanceof ResourceManager) 
				|| rm.contains(cls)) {
			return cls;
		} 

		throw new AgletsSecurityException();
	}
	static Object toObject(ResourceManager rm, byte[] b) 
			throws OptionalDataException, ClassNotFoundException, 
				   IOException {
		ByteArrayInputStream in = new ByteArrayInputStream(b);
		MessageInputStream ois = new MessageInputStream(in, rm);

		return ois.readObject();
	}
}