Java tutorial
/* * Copyright (c) 2012-2015 The original author or authors * ------------------------------------------------------ * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * and Apache License v2.0 which accompanies this distribution. * * The Eclipse Public License is available at * http://www.eclipse.org/legal/epl-v10.html * * The Apache License v2.0 is available at * http://www.opensource.org/licenses/apache2.0.php * * You may elect to redistribute this code under either of these licenses. */ package org.jmqtt.core.codec; import io.netty.buffer.ByteBuf; import io.netty.channel.ChannelHandlerContext; import org.jmqtt.core.constant.QosType; import org.jmqtt.core.packet.AbstractPacket; import org.jmqtt.core.packet.SubscribePacket; import org.jmqtt.core.util.MqttUtils; /** * @author andrea */ class SubscribeEncoder extends DemuxEncoder<SubscribePacket> { @Override protected void encode(ChannelHandlerContext chc, SubscribePacket message, ByteBuf out) { if (message.subscriptions().isEmpty()) { throw new IllegalArgumentException("Found a subscribe message with empty topics"); } if (message.getQos() != QosType.LEAST_ONE) { throw new IllegalArgumentException("Expected a message with QOS 1, found " + message.getQos()); } ByteBuf variableHeaderBuff = chc.alloc().buffer(4); ByteBuf buff = null; try { variableHeaderBuff.writeShort(message.getPacketId()); for (SubscribePacket.Couple c : message.subscriptions()) { variableHeaderBuff.writeBytes(MqttUtils.encodeString(c.topicFilter)); variableHeaderBuff.writeByte(c.qos); } int variableHeaderSize = variableHeaderBuff.readableBytes(); byte flags = MqttUtils.encodeFlags(message); buff = chc.alloc().buffer(2 + variableHeaderSize); buff.writeByte(AbstractPacket.SUBSCRIBE << 4 | flags); buff.writeBytes(MqttUtils.encodeRemainingLength(variableHeaderSize)); buff.writeBytes(variableHeaderBuff); out.writeBytes(buff); } finally { variableHeaderBuff.release(); buff.release(); } } }