/*
* JBoss, Home of Professional Open Source
*
* Copyright 2008, Red Hat Middleware LLC, and individual contributors
* by the @author tags. See the COPYRIGHT.txt in the distribution for a
* full listing of individual contributors.
*
* This is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* This software 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this software; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
* 02110-1301 USA, or see the FSF site: http://www.fsf.org.
*/
package org.jboss.netty.handler.codec.string;
import static org.jboss.netty.channel.Channels.*;
import java.nio.charset.Charset;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.channel.ChannelEvent;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.channel.ChannelPipelineCoverage;
import org.jboss.netty.channel.ChannelUpstreamHandler;
import org.jboss.netty.channel.MessageEvent;
import org.jboss.netty.handler.codec.frame.DelimiterBasedFrameDecoder;
import org.jboss.netty.handler.codec.frame.Delimiters;
import org.jboss.netty.handler.codec.frame.FrameDecoder;
/**
* Decodes a received {@link ChannelBuffer} into a {@link String}. Please
* note that this decoder must be used with a proper {@link FrameDecoder}
* such as {@link DelimiterBasedFrameDecoder} if you are using a stream-based
* transport such as TCP/IP. A typical decoder setup for a text-based line
* protocol in a TCP/IP socket would be:
* <pre>
* {@link ChannelPipeline} pipeline = ...;
*
* // Decoders
* pipeline.addLast("frameDecoder", new {@link DelimiterBasedFrameDecoder}(80, {@link Delimiters#lineDelimiter()}));
* pipeline.addLast("stringDecoder", new {@link StringDecoder}("UTF-8"));
*
* // Encoder
* pipeline.addLast("stringEncoder", new {@link StringEncoder}("UTF-8"));
* </pre>
* and then you can use {@link String}s instead of {@link ChannelBuffer}s
* as a message:
* <pre>
* void messageReceived(ChannelHandlerContext ctx, MessageEvent e) {
* String msg = (String) e.getMessage();
* ch.write("Did you say '" + msg + "'?\n");
* }
* </pre>
*
* @author The Netty Project (netty-dev@lists.jboss.org)
* @author Trustin Lee (tlee@redhat.com)
*
* @version $Rev:231 $, $Date:2008-06-12 16:44:50 +0900 (목, 12 6월 2008) $
*
* @apiviz.landmark
*/
@ChannelPipelineCoverage("all")
public class StringDecoder implements ChannelUpstreamHandler {
private final String charsetName;
/**
* Creates a new instance with the current system character set.
*/
public StringDecoder() {
this(Charset.defaultCharset());
}
/**
* Creates a new instance.
*
* @param charsetName the name of the character set to use for decoding
*/
public StringDecoder(String charsetName) {
this(Charset.forName(charsetName));
}
/**
* Creates a new instance.
*
* @param charset the character set to use for decoding
*/
public StringDecoder(Charset charset) {
if (charset == null) {
throw new NullPointerException("charset");
}
charsetName = charset.name();
}
public void handleUpstream(
ChannelHandlerContext context, ChannelEvent evt) throws Exception {
if (!(evt instanceof MessageEvent)) {
context.sendUpstream(evt);
return;
}
MessageEvent e = (MessageEvent) evt;
if (!(e.getMessage() instanceof ChannelBuffer)) {
context.sendUpstream(evt);
return;
}
fireMessageReceived(
context, e.getChannel(),
((ChannelBuffer) e.getMessage()).toString(charsetName));
}
}