formatablehashtable.java

derby database source code.good for you.

/*

   Derby - Class org.apache.derby.iapi.services.io.FormatableHashtable

   Copyright 1999, 2004 The Apache Software Foundation or its licensors, as applicable.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

 */

package org.apache.derby.iapi.services.io;

import org.apache.derby.iapi.services.io.ArrayInputStream;

import org.apache.derby.iapi.services.io.StoredFormatIds;
import org.apache.derby.iapi.services.io.FormatIdUtil;
import org.apache.derby.iapi.services.io.Formatable;
import org.apache.derby.iapi.services.sanity.SanityManager;

import java.util.Hashtable;
import java.util.Enumeration;
import java.io.ObjectOutput;
import java.io.ObjectInput;
import java.io.IOException;


/**
 * A formatable holder for a java.util.Hashtable.
 * Used to avoid serializing Properties.
 */
public class FormatableHashtable extends Hashtable implements Formatable
{
	/********************************************************
	**
	**	This class implements Formatable. That means that it
	**	can write itself to and from a formatted stream. If
	**	you add more fields to this class, make sure that you
	**	also write/read them with the writeExternal()/readExternal()
	**	methods.
	**
	**	If, inbetween releases, you add more fields to this class,
	**	then you should bump the version number emitted by the getTypeFormatId()
	**	method.
	**
	********************************************************/

	/**
	 * Niladic constructor for formatable
	 */
	public FormatableHashtable() 
	{
	}


	/**
	 * Our special put method that wont barf
	 * on a null value.
	 * @see java.util.Hashtable
	 */
	public Object put(Object key, Object value)
	{
		if (value == null)
		{
			return remove(key);
		}

		if (SanityManager.DEBUG) {

		if ((value instanceof FormatableIntHolder) ||
			(value instanceof FormatableLongHolder) ||
			((value instanceof java.io.Serializable) && (!(value instanceof Formatable)) && (!(value instanceof String)))
			) {

			if (!value.getClass().isArray()) {

				// System.out.println("key " + key + " class " + value.getClass());
				//new Throwable().printStackTrace(System.out);
				//System.exit(1);
			}
		}
		}
		return super.put(key, value);
	}

	public void putInt(Object key, int value) {

		super.put(key, new FormatableIntHolder(value));
	}

	public int getInt(Object key) {

		return ((FormatableIntHolder) get(key)).getInt();
	}
	public void putLong(Object key, long value) {

		super.put(key, new FormatableLongHolder(value));
	}

	public long getLong(Object key) {

		return ((FormatableLongHolder) get(key)).getLong();
	}
	public void putBoolean(Object key, boolean value) {

		putInt(key,value ? 1 : 0);
	}

	public boolean getBoolean(Object key) {

		return getInt(key) == 0 ? false : true;

	}

	//////////////////////////////////////////////
	//
	// FORMATABLE
	//
	//////////////////////////////////////////////
	/**
	 * Write the hash table out.  Step through
	 * the enumeration and write the strings out
	 * in UTF.
	 *
	 * @param out write bytes here
	 *
 	 * @exception IOException thrown on error
	 */
	public void writeExternal(ObjectOutput out) throws IOException
	{
		out.writeInt(size());
		for (Enumeration e = keys(); e.hasMoreElements(); )
		{
			Object key = e.nextElement();
			out.writeObject(key);
			out.writeObject(get(key));
			
			if (SanityManager.DEBUG)
			{
				Object value = get(key);
				if (value instanceof Formatable[])
				{
					SanityManager.THROWASSERT("you should be using FormatableArrayHolder rather than writing out an array of Formatables, otherwise you will get bad behavior for null Storables.  Your class is a "+value.getClass().getName());
				}
			}
		}
	}					

	/**
	 * Read the hash table from a stream of stored objects.
	 *
	 * @param in read this.
	 *
	 * @exception IOException					thrown on error
	 * @exception ClassNotFoundException		thrown on error
	 */
	public void readExternal(ObjectInput in)
		throws IOException, ClassNotFoundException
	{
		int size = in.readInt();
		for (; size > 0; size--)
		{
			super.put(in.readObject(), in.readObject());
		}
	}
	public void readExternal(ArrayInputStream in)
		throws IOException, ClassNotFoundException
	{
		int size = in.readInt();
		for (; size > 0; size--)
		{
			super.put(in.readObject(), in.readObject());
		}
	}
	
	/**
	 * Get the formatID which corresponds to this class.
	 *
	 *	@return	the formatID of this class
	 */
	public	int	getTypeFormatId()	{ return StoredFormatIds.FORMATABLE_HASHTABLE_V01_ID; }
}