89 lines
3.3 KiB
Java
89 lines
3.3 KiB
Java
/*
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* Copyright 2015 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.handler.codec.protobuf;
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import static java.util.Objects.requireNonNull;
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import com.google.protobuf.nano.MessageNano;
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import java.util.List;
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import io.netty.buffer.ByteBuf;
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import io.netty.buffer.ByteBufUtil;
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import io.netty.channel.ChannelHandler.Sharable;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.channel.ChannelPipeline;
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import io.netty.handler.codec.ByteToMessageDecoder;
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import io.netty.handler.codec.LengthFieldBasedFrameDecoder;
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import io.netty.handler.codec.MessageToMessageDecoder;
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/**
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* Decodes a received {@link ByteBuf} into a
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* <a href="https://github.com/google/protobuf">Google Protocol Buffers</a>
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* {@link MessageNano}. Please note that this decoder must
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* be used with a proper {@link ByteToMessageDecoder} such as {@link LengthFieldBasedFrameDecoder}
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* if you are using a stream-based transport such as TCP/IP. A typical setup for TCP/IP would be:
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* <pre>
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* {@link ChannelPipeline} pipeline = ...;
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*
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* // Decoders
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* pipeline.addLast("frameDecoder",
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* new {@link LengthFieldBasedFrameDecoder}(1048576, 0, 4, 0, 4));
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* pipeline.addLast("protobufDecoder",
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* new {@link ProtobufDecoderNano}(MyMessage.getDefaultInstance()));
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*
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* // Encoder
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* pipeline.addLast("frameEncoder", new {@link io.netty.handler.codec.LengthFieldPrepender}(4));
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* pipeline.addLast("protobufEncoder", new {@link ProtobufEncoderNano}());
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* </pre>
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* and then you can use a {@code MyMessage} instead of a {@link ByteBuf}
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* as a message:
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* <pre>
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* void channelRead({@link ChannelHandlerContext} ctx, Object msg) {
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* MyMessage req = (MyMessage) msg;
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* MyMessage res = MyMessage.newBuilder().setText(
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* "Did you say '" + req.getText() + "'?").build();
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* ch.write(res);
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* }
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* </pre>
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*/
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@Sharable
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public class ProtobufDecoderNano extends MessageToMessageDecoder<ByteBuf> {
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private final Class<? extends MessageNano> clazz;
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/**
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* Creates a new instance.
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*/
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public ProtobufDecoderNano(Class<? extends MessageNano> clazz) {
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this.clazz = requireNonNull(clazz, "You must provide a Class");
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}
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@Override
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protected void decode(ChannelHandlerContext ctx, ByteBuf msg) throws Exception {
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final byte[] array;
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final int offset;
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final int length = msg.readableBytes();
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if (msg.hasArray()) {
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array = msg.array();
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offset = msg.arrayOffset() + msg.readerIndex();
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} else {
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array = ByteBufUtil.getBytes(msg, msg.readerIndex(), length, false);
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offset = 0;
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}
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MessageNano prototype = clazz.getConstructor().newInstance();
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ctx.fireChannelRead(MessageNano.mergeFrom(prototype, array, offset, length));
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}
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}
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