mqtt java和android,编写和MQTT服务器通信的Android客户端程序（二）
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。