Android使用MQTT协议

MQTT是一个轻量级的消息发布/订阅协议，它是实现基于手机客户端的消息推送服务器的理想解决方案。
jar包下载地址：https://repo.eclipse.org/content/repositories/paho/org/eclipse/paho/mqtt-client/0.4.0/
在Android客户端中MainAcitvity的代码如下：

package com.xiye.mqttdemo;import android.app.Notification;import android.app.NotificationManager;import android.content.Context;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.support.v7.app.AppCompatActivity;import android.util.Log;import android.view.KeyEvent;import android.widget.RemoteViews;import android.widget.TextView;import android.widget.Toast;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 java.util.concurrent.Executors;import java.util.concurrent.ScheduledExecutorService;import java.util.concurrent.TimeUnit;@SuppressWarnings("all")public class MainActivity extends AppCompatActivity {    private TextView resultTv;    private String host = "tcp://host:1883";    private String userName = "userName";    private String passWord = "passWord";    private int i = 1;    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.activity_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();                    Log.e("TAG",(String)msg.obj);                } else if (msg.what == 2) {                    System.out.println("连接成功");                    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();                    System.out.println("连接失败，系统正在重连");                }            }        };        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, "ClientID",                    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(50);            //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);                }            });        } catch (Exception e) {            Log.e("TAG",e.getMessage().toString());            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();        }    }}