Java tutorial
/* * Copyright 2014-2015 Open Networking Laboratory * * 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.onlab.netty; import static com.google.common.base.Preconditions.checkState; import io.netty.buffer.ByteBuf; import io.netty.channel.ChannelHandlerContext; import io.netty.handler.codec.ReplayingDecoder; import java.util.List; import org.onlab.packet.IpAddress; import org.onlab.packet.IpAddress.Version; import org.onosproject.store.cluster.messaging.Endpoint; import org.slf4j.Logger; import org.slf4j.LoggerFactory; import com.google.common.base.Charsets; /** * Decoder for inbound messages. */ public class MessageDecoder extends ReplayingDecoder<DecoderState> { private final Logger log = LoggerFactory.getLogger(getClass()); private long messageId; private Version ipVersion; private IpAddress senderIp; private int senderPort; private int messageTypeLength; private String messageType; private int contentLength; public MessageDecoder() { super(DecoderState.READ_MESSAGE_ID); } @Override protected void decode(ChannelHandlerContext context, ByteBuf buffer, List<Object> out) throws Exception { switch (state()) { case READ_MESSAGE_ID: messageId = buffer.readLong(); checkpoint(DecoderState.READ_SENDER_IP_VERSION); case READ_SENDER_IP_VERSION: ipVersion = buffer.readByte() == 0x0 ? Version.INET : Version.INET6; checkpoint(DecoderState.READ_SENDER_IP); case READ_SENDER_IP: byte[] octects = new byte[IpAddress.byteLength(ipVersion)]; buffer.readBytes(octects); senderIp = IpAddress.valueOf(ipVersion, octects); checkpoint(DecoderState.READ_SENDER_PORT); case READ_SENDER_PORT: senderPort = buffer.readInt(); checkpoint(DecoderState.READ_MESSAGE_TYPE_LENGTH); case READ_MESSAGE_TYPE_LENGTH: messageTypeLength = buffer.readInt(); checkpoint(DecoderState.READ_MESSAGE_TYPE); case READ_MESSAGE_TYPE: byte[] messageTypeBytes = new byte[messageTypeLength]; buffer.readBytes(messageTypeBytes); messageType = new String(messageTypeBytes, Charsets.UTF_8); checkpoint(DecoderState.READ_CONTENT_LENGTH); case READ_CONTENT_LENGTH: contentLength = buffer.readInt(); checkpoint(DecoderState.READ_CONTENT); case READ_CONTENT: byte[] payload = new byte[contentLength]; buffer.readBytes(payload); InternalMessage message = new InternalMessage(messageId, new Endpoint(senderIp, senderPort), messageType, payload); out.add(message); checkpoint(DecoderState.READ_MESSAGE_ID); break; default: checkState(false, "Must not be here"); } } @Override public void exceptionCaught(ChannelHandlerContext context, Throwable cause) { log.error("Exception inside channel handling pipeline.", cause); context.close(); } }