MQTT协议的简单介绍和服务器的安装
最近公司做的项目中有用到消息推送,经过多方面的筛选之后确定了使用MQTT协议,相对于XMPP,MQTT更加轻量级,并且占用用户很少的带宽。
MQTT是IBM推出的一种针对移动终端设备的基于TCP/IP的发布/预订协议,可以连接大量的远程传感器和控制设备。
MQTT的官网见:http://mqtt.org/。其中http://mqtt.org/software里面提供了官方推荐的各种服务器和客户端使用的各种语言版本的API。
下面以服务器Apollo 1.6为例,之前尝试过使用ActiveMQ,效果很不理想,只能实现服务器和客户端一对一的通信,从官网上了解到Apollo属于activemq的一个子工程。先不管这些了,言归正传,以下在windows环境下。
1、在这里下载Apollo服务器,下载后解压,然后运行apache-apollo-1.6\bin\apollo.cmd,输入create mybroker(名字任意取,这里是根据官网介绍的来取的)创建服务器实例,服务器实例包含了所有的配置,运行时数据等,并且和一个服务器进程关联。
2、create mybroker之后会在bin目录下生成mybroker文件夹,里面包含有很多信息,其中etc\apollo.xml文件下是配置服务器信息的文件,etc\users.properties文件包含连接MQTT服务器时用到的用户名和密码,后面会介绍,可以修改原始的admin=password,可以接着换行添加新的用户名密码。
3、打开cmd,运行…apache-apollo-1.6\bin\mybroker\bin\apollo-broker.cmd run 开启服务器,可以在浏览器中输入http://127.0.0.1:61680/查看是否安装成功,该界面展示了topic,连接数等很多信息。
经过上面的简单步骤,服务器基本上就已经完成,下一篇将介绍Android客户端的编写和注意事项。
客户端使用的API,开始我使用的是mqtt-client,使用过后发现问题百出,不能很好的满足要求,后来使用了官方推荐的Eclipse Paho,下面开始客户端代码的编写,为了方便测试这里有android和j2se两个工程:
1、新建android工程MQTTClient
2、MainActivity代码如下:
- package ldw.mqttclient;
- import java.util.concurrent.Executors;
- import java.util.concurrent.ScheduledExecutorService;
- import java.util.concurrent.TimeUnit;
- import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
- import org.eclipse.paho.client.mqttv3.MqttCallback;
- import org.eclipse.paho.client.mqttv3.MqttClient;
- import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
- import org.eclipse.paho.client.mqttv3.MqttException;
- import org.eclipse.paho.client.mqttv3.MqttMessage;
- import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
- import android.app.Activity;
- import android.os.Bundle;
- import android.os.Handler;
- import android.os.Message;
- import android.view.KeyEvent;
- import android.widget.TextView;
- import android.widget.Toast;
- public class MainActivity extends Activity {
- private TextView resultTv;
- private String host = "tcp://127.0.0.1:1883";
- private String userName = "admin";
- private String passWord = "password";
- private Handler handler;
- private MqttClient client;
- private String myTopic = "test/topic";
- private MqttConnectOptions options;
- private ScheduledExecutorService scheduler;
- @Override
- protected void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.main);
- resultTv = (TextView) findViewById(R.id.result);
- init();
- handler = new Handler() {
- @Override
- public void handleMessage(Message msg) {
- super.handleMessage(msg);
- if(msg.what == 1) {
- Toast.makeText(MainActivity.this, (String) msg.obj,
- Toast.LENGTH_SHORT).show();
- System.out.println("-----------------------------");
- } else if(msg.what == 2) {
- Toast.makeText(MainActivity.this, "连接成功", Toast.LENGTH_SHORT).show();
- try {
- client.subscribe(myTopic, 1);
- } catch (Exception e) {
- e.printStackTrace();
- }
- } else if(msg.what == 3) {
- Toast.makeText(MainActivity.this, "连接失败,系统正在重连", Toast.LENGTH_SHORT).show();
- }
- }
- };
- startReconnect();
- }
- private void startReconnect() {
- scheduler = Executors.newSingleThreadScheduledExecutor();
- scheduler.scheduleAtFixedRate(new Runnable() {
- @Override
- public void run() {
- if(!client.isConnected()) {
- connect();
- }
- }
- }, 0 * 1000, 10 * 1000, TimeUnit.MILLISECONDS);
- }
- private void init() {
- try {
- //host为主机名,test为clientid即连接MQTT的客户端ID,一般以客户端唯一标识符表示,MemoryPersistence设置clientid的保存形式,默认为以内存保存
- client = new MqttClient(host, "test",
- new MemoryPersistence());
- //MQTT的连接设置
- options = new MqttConnectOptions();
- //设置是否清空session,这里如果设置为false表示服务器会保留客户端的连接记录,这里设置为true表示每次连接到服务器都以新的身份连接
- options.setCleanSession(true);
- //设置连接的用户名
- options.setUserName(userName);
- //设置连接的密码
- options.setPassword(passWord.toCharArray());
- // 设置超时时间 单位为秒
- options.setConnectionTimeout(10);
- // 设置会话心跳时间 单位为秒 服务器会每隔1.5*20秒的时间向客户端发送个消息判断客户端是否在线,但这个方法并没有重连的机制
- options.setKeepAliveInterval(20);
- //设置回调
- client.setCallback(new MqttCallback() {
- @Override
- public void connectionLost(Throwable cause) {
- //连接丢失后,一般在这里面进行重连
- System.out.println("connectionLost----------");
- }
- @Override
- public void deliveryComplete(IMqttDeliveryToken token) {
- //publish后会执行到这里
- System.out.println("deliveryComplete---------"
- + token.isComplete());
- }
- @Override
- public void messageArrived(String topicName, MqttMessage message)
- throws Exception {
- //subscribe后得到的消息会执行到这里面
- System.out.println("messageArrived----------");
- Message msg = new Message();
- msg.what = 1;
- msg.obj = topicName+"---"+message.toString();
- handler.sendMessage(msg);
- }
- });
- // connect();
- } catch (Exception e) {
- e.printStackTrace();
- }
- }
- private void connect() {
- new Thread(new Runnable() {
- @Override
- public void run() {
- try {
- client.connect(options);
- Message msg = new Message();
- msg.what = 2;
- handler.sendMessage(msg);
- } catch (Exception e) {
- e.printStackTrace();
- Message msg = new Message();
- msg.what = 3;
- handler.sendMessage(msg);
- }
- }
- }).start();
- }
- @Override
- public boolean onKeyDown(int keyCode, KeyEvent event) {
- if(client != null && keyCode == KeyEvent.KEYCODE_BACK) {
- try {
- client.disconnect();
- } catch (Exception e) {
- e.printStackTrace();
- }
- }
- return super.onKeyDown(keyCode, event);
- }
- @Override
- protected void onDestroy() {
- super.onDestroy();
- try {
- scheduler.shutdown();
- client.disconnect();
- } catch (MqttException e) {
- e.printStackTrace();
- }
- }
- }
由于项目需要,我用到了心跳重连。根据这里的解释设置apollo.xml,主要有设置主机连接的地址。另外,options还有个setWill方法,如果项目中需要知道客户端是否掉线可以调用该方法。
3、新建j2se工程MQTTServer
4、Server代码如下:
- import java.awt.Container;
- import java.awt.event.ActionEvent;
- import java.awt.event.ActionListener;
- import javax.swing.JButton;
- import javax.swing.JFrame;
- import javax.swing.JPanel;
- import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
- import org.eclipse.paho.client.mqttv3.MqttCallback;
- import org.eclipse.paho.client.mqttv3.MqttClient;
- import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
- import org.eclipse.paho.client.mqttv3.MqttDeliveryToken;
- import org.eclipse.paho.client.mqttv3.MqttMessage;
- import org.eclipse.paho.client.mqttv3.MqttTopic;
- import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
- public class Server extends JFrame {
- private static final long serialVersionUID = 1L;
- private JPanel panel;
- private JButton button;
- private MqttClient client;
- private String host = "tcp://127.0.0.1:1883";
- // private String host = "tcp://localhost:1883";
- private String userName = "test";
- private String passWord = "test";
- private MqttTopic topic;
- private MqttMessage message;
- private String myTopic = "test/topic";
- public Server() {
- try {
- client = new MqttClient(host, "Server",
- new MemoryPersistence());
- connect();
- } catch (Exception e) {
- e.printStackTrace();
- }
- Container container = this.getContentPane();
- panel = new JPanel();
- button = new JButton("发布话题");
- button.addActionListener(new ActionListener() {
- @Override
- public void actionPerformed(ActionEvent ae) {
- try {
- MqttDeliveryToken token = topic.publish(message);
- token.waitForCompletion();
- System.out.println(token.isComplete()+"========");
- } catch (Exception e) {
- e.printStackTrace();
- }
- }
- });
- panel.add(button);
- container.add(panel, "North");
- }
- private void connect() {
- MqttConnectOptions options = new MqttConnectOptions();
- options.setCleanSession(false);
- options.setUserName(userName);
- options.setPassword(passWord.toCharArray());
- // 设置超时时间
- options.setConnectionTimeout(10);
- // 设置会话心跳时间
- options.setKeepAliveInterval(20);
- try {
- client.setCallback(new MqttCallback() {
- @Override
- public void connectionLost(Throwable cause) {
- System.out.println("connectionLost-----------");
- }
- @Override
- public void deliveryComplete(IMqttDeliveryToken token) {
- System.out.println("deliveryComplete---------"+token.isComplete());
- }
- @Override
- public void messageArrived(String topic, MqttMessage arg1)
- throws Exception {
- System.out.println("messageArrived----------");
- }
- });
- topic = client.getTopic(myTopic);
- message = new MqttMessage();
- message.setQos(1);
- message.setRetained(true);
- System.out.println(message.isRetained()+"------ratained状态");
- message.setPayload("eeeeeaaaaaawwwwww---".getBytes());
- client.connect(options);
- } catch (Exception e) {
- e.printStackTrace();
- }
- }
- public static void main(String[] args) {
- Server s = new Server();
- s.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
- s.setSize(600, 370);
- s.setLocationRelativeTo(null);
- s.setVisible(true);
- }
- }
上面代码跟客户端的代码差不多,这里就不做解释了。
没什么好说的,MQTT就是这么简单,但开始在使用的时候要注意一些参数的设置来适应项目的需求。
jar包下载地址:
https://repo.eclipse.org/content/repositories/paho/org/eclipse/paho/mqtt-client/0.4.0/
posted on 2015-12-22 11:44 clarenceV1 阅读(275) 评论(0) 编辑 收藏 举报