以Apollo服务器作为中间件,模拟MQTT客户端,MQTT订阅接受消息

一、Windows下安装Apollo

下载链接：http://activemq.apache.org/apollo/download.html

解压至C:\ 根目录下（可自选）本文以C盘根目录为例

二、创建apollo实例，如图操作：

打开cmd,编辑命令 

三、启动apollo实例（cmd命令切换至刚创建的实例目录下的bin目录下敲入 apollo-broker run），如下图可看到apollo的启动情况

可进入http://localhost:61680 查看apollo后台（登录名默认为admin 密码为password）

四、创建模拟发送消息的客户端，代码如下

package com.vin.foo;import org.fusesource.hawtbuf.Buffer;import org.fusesource.hawtbuf.UTF8Buffer;import org.fusesource.mqtt.client.FutureConnection;import org.fusesource.mqtt.client.MQTT;import org.fusesource.mqtt.client.QoS;public class MQTTClient {public static void main(String[] args) throws Exception {sendMessage("hello");}public static void sendMessage(String message) {String user = env("APOLLO_USER", "admin");String password = env("APOLLO_PASSWORD", "password");String host = env("APOLLO_HOST", "localhost");//apollo服务器地址int port = 61613;//apollo端口号String destination = "/topic/1/OOOOOOOOOO/aaaa";//topicBuffer msg = new UTF8Buffer(message);MQTT mqtt = new MQTT();//新建MQTTtry {mqtt.setHost(host, port);mqtt.setUserName(user);mqtt.setPassword(password);FutureConnection connection = mqtt.futureConnection();connection.connect().await();UTF8Buffer topic = new UTF8Buffer(destination);connection.publish(topic, msg, QoS.AT_LEAST_ONCE, false);connection.disconnect().await();} catch (Exception e) {e.printStackTrace();} finally {// System.exit(0);}}private static String env(String key, String defaultValue) {String rc = System.getenv(key);if (rc == null) {return defaultValue;}return rc;}}</span>

五、创建接受消息的订阅者</span>

/** * Licensed to the Apache Software Foundation (ASF) under one or more   */package com.vin.foo;import org.fusesource.hawtbuf.Buffer;import org.fusesource.hawtbuf.UTF8Buffer;import org.fusesource.mqtt.client.Callback;import org.fusesource.mqtt.client.CallbackConnection;import org.fusesource.mqtt.client.Listener;import org.fusesource.mqtt.client.MQTT;import org.fusesource.mqtt.client.QoS;import org.fusesource.mqtt.client.Topic;/** * Uses an callback based interface to MQTT. Callback based interfaces are * harder to use but are slightly more efficient. */class MQTTListener {public static void main(String[] args) throws Exception {String user = env("APOLLO_USER", "admin");String password = env("APOLLO_PASSWORD", "password");String host = env("APOLLO_HOST", "localhost");int port = Integer.parseInt(env("APOLLO_PORT", "61613"));final String destination = arg(args, 0, "/topic/1/OOOOOOOOOO/aaaa");MQTT mqtt = new MQTT();mqtt.setHost(host, port);mqtt.setUserName(user);mqtt.setPassword(password);mqtt.setKeepAlive((short) 30);// mqtt.setCleanSession(false);// mqtt.setClientId("aaaa");final CallbackConnection connection = mqtt.callbackConnection();connection.listener(new Listener() {public void onConnected() {}public void onDisconnected() {}public void onFailure(Throwable value) {value.printStackTrace();System.exit(-2);}public void onPublish(UTF8Buffer topic, Buffer msg, Runnable ack) {String body = msg.utf8().toString();System.out.println(body);ack.run();}});connection.connect(new Callback<Void>() {@Overridepublic void onSuccess(Void value) {Topic[] topics = { new Topic(destination, QoS.AT_LEAST_ONCE) };connection.subscribe(topics, new Callback<byte[]>() {public void onSuccess(byte[] qoses) {System.out.println("connected...");}public void onFailure(Throwable value) {value.printStackTrace();System.exit(-2);}});}@Overridepublic void onFailure(Throwable value) {value.printStackTrace();System.exit(-2);}});// Wait forever..synchronized (MQTTListener.class) {while (true) {MQTTListener.class.wait();}}}private static String env(String key, String defaultValue) {String rc = System.getenv(key);if (rc == null) {return defaultValue;}return rc;}private static String arg(String[] args, int index, String defaultValue) {if (index < args.length) {return args[index];} else {return defaultValue;}}}

</pre><pre name="code" class="java">六、运行MQTTListener，可建立一个topic长连接/topic/1/OOOOOOOOOO/aaaa，运行MQTTClient可向订阅者/topic/1/OOOOOOOOOO/aaaa发送一个“hello”消息。可在后台查看连接状态，也可在java控制台看到接受的消息。</span>

代码中具体各参数的定义请参考我上一篇转载MQTT协议规范的文章