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/**
* Copyright (c) 2004 - 2009 Eike Stepper (Berlin, Germany) and others.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Eike Stepper - initial API and implementation
*/
package org.eclipse.net4j.util.io;
import java.io.IOException;
import java.text.MessageFormat;
import java.util.HashMap;
import java.util.Map;
/**
* TODO Detect possible race condition and let the client win.
*
* @author Eike Stepper
* @since 2.0
*/
public class StringCompressor implements StringIO
{
private boolean client;
private int lastID;
private Map<String, Integer> stringToID = new HashMap<String, Integer>();
private Map<Integer, String> idToString = new HashMap<Integer, String>();
/**
* Creates a StringCompressor instance.
*
* @param client
* Must be different on both sides of the stream.
*/
public StringCompressor(boolean client)
{
this.client = client;
}
public boolean isClient()
{
return client;
}
public void write(ExtendedDataOutput out, String string) throws IOException
{
if (string == null)
{
out.writeInt(0);
return;
}
int idToWrite;
String stringToWrite;
synchronized (stringToID)
{
Integer id = stringToID.get(string);
if (id == null)
{
lastID += client ? 1 : -1;
stringToID.put(string, lastID);
idToString.put(lastID, string);
idToWrite = lastID;
stringToWrite = string;
}
else
{
idToWrite = id;
stringToWrite = null;
}
}
out.writeInt(idToWrite);
if (stringToWrite != null)
{
out.writeString(stringToWrite);
}
}
public String read(ExtendedDataInput in) throws IOException
{
int id = in.readInt();
if (id == 0)
{
return null;
}
String string;
synchronized (stringToID)
{
string = idToString.get(id);
}
// TODO Check if we need a single synchronized block
if (string == null)
{
string = in.readString();
synchronized (stringToID)
{
stringToID.put(string, id);
idToString.put(id, string);
}
}
return string;
}
@Override
public String toString()
{
return MessageFormat.format("Compressor[client={0}]", client);
}
}
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