io.netty.handler.codec.string.StringDecoder Maven / Gradle / Ivy
/*
* Copyright 2012 The Netty Project
*
* The Netty Project licenses this file to you 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 io.netty.handler.codec.string;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandler.Sharable;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import io.netty.handler.codec.ByteToMessageDecoder;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.LineBasedFrameDecoder;
import io.netty.handler.codec.MessageToMessageDecoder;
import java.nio.charset.Charset;
/**
* Decodes a received {@link ByteBuf} into a {@link String}. Please
* note that this decoder must be used with a proper {@link ByteToMessageDecoder}
* such as {@link DelimiterBasedFrameDecoder} or {@link LineBasedFrameDecoder}
* if you are using a stream-based transport such as TCP/IP. A typical setup for a
* text-based line protocol in a TCP/IP socket would be:
*
* {@link ChannelPipeline} pipeline = ...;
*
* // Decoders
* pipeline.addLast("frameDecoder", new {@link LineBasedFrameDecoder}(80));
* pipeline.addLast("stringDecoder", new {@link StringDecoder}(CharsetUtil.UTF_8));
*
* // Encoder
* pipeline.addLast("stringEncoder", new {@link StringEncoder}(CharsetUtil.UTF_8));
*
* and then you can use a {@link String} instead of a {@link ByteBuf}
* as a message:
*
* void messageReceived({@link ChannelHandlerContext} ctx, {@link String} msg) {
* ch.write("Did you say '" + msg + "'?\n");
* }
*
*/
@Sharable
public class StringDecoder extends MessageToMessageDecoder {
// TODO Use CharsetDecoder instead.
private final Charset charset;
/**
* Creates a new instance with the current system character set.
*/
public StringDecoder() {
this(Charset.defaultCharset());
}
/**
* Creates a new instance with the specified character set.
*/
public StringDecoder(Charset charset) {
if (charset == null) {
throw new NullPointerException("charset");
}
this.charset = charset;
}
@Override
protected Object decode(ChannelHandlerContext ctx, ByteBuf msg) throws Exception {
return msg.toString(charset);
}
}