Preface
We have built and tested the Broker server of MQTT.fx, and now we want to use the Android client point to communicate with the server.
An existing library for communicating with Android is Paho Android Service.
Paho Android Service is an MQTT client service package developed based on the Paho MQTT library of Java language.
Access
- Add warehouse address in build.gradle
maven {
url "https://repo.eclipse.org/content/repositories/paho-snapshots/"
}
或者是
maven {
url "https://repo.eclipse.org/content/repositories/paho-releases/"
}
- Introduce dependencies in App or sub-Module
dependencies {
implementation 'org.eclipse.paho:org.eclipse.paho.client.mqttv3:1.1.0'
implementation 'org.eclipse.paho:org.eclipse.paho.android.service:1.1.1'
}
- Add permissions and register Service in the AndroidManifest file
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="xxx.xxxx.mqtt">
<uses-permission android:name="android.permission.WAKE_LOCK" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.READ_PHONE_STATE" />
<application>
<service android:name="org.eclipse.paho.android.service.MqttService" />
</application>
</manifest>
application
- The following is the code for establishment and subscription
public class IOT {
private final String TAG = "MyIOT";
private Context mContext;
/* 用于上报消息 */
final private String PUB_TOPIC = "/message/publish";
/* 用于接受消息 */
final private String SUB_TOPIC = "/message/publish";
/* 自己部署到本地的服务器地址（协议+地址+端口号） */
private final String HOST = "tcp://替换成自己的IP:1883";
/* 用户名 */
private String USERNAME = "admin";
/* 密码 */
private String PASSWORD = "admin";
private MqttAndroidClient mqttAndroidClient;
private static final class IOTHolder {
private static final IOT instance = new IOT();
}
public static IOT getInstance() {
return IOT.IOTHolder.instance;
}
/**
* 初始化
*
* @param context
*/
public void init(Context context) {
mContext = context.getApplicationContext();
connect();
}
/**
* 订阅特定的主题
*
* @param topic mqtt主题
*/
public void subscribeTopic(String topic) {
try {
mqttAndroidClient.subscribe(topic, 0, null, new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
Log.i(TAG, "subscribed succeed");
}
@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
Log.i(TAG, "subscribed failed");
}
});
} catch (MqttException e) {
e.printStackTrace();
}
}
/**
* 向默认的主题/user/update发布消息
*
* @param payload 消息载荷
*/
public void publishMessage(String payload) {
try {
if (!mqttAndroidClient.isConnected()) {
mqttAndroidClient.connect();
}
MqttMessage message = new MqttMessage();
message.setPayload(payload.getBytes());
message.setQos(0);
mqttAndroidClient.publish(PUB_TOPIC, message, null, new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
Log.i(TAG, "publish succeed!");
}
@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
Log.i(TAG, "publish failed!");
}
});
} catch (MqttException e) {
Log.e(TAG, e.toString());
e.printStackTrace();
}
}
/**
* 断开连接销毁资源
*/
public void destroy() {
try {
if (mqttAndroidClient.isConnected()) {
mqttAndroidClient.disconnect();
mqttAndroidClient.unregisterResources();
}
mqttAndroidClient = null;
} catch (MqttException e) {
e.printStackTrace();
}
}
/**
* 断开连接
*/
public void disconnect() {
try {
if (mqttAndroidClient.isConnected()) {
mqttAndroidClient.disconnect();
}
} catch (MqttException e) {
e.printStackTrace();
}
}
/**
* 重新连接
*/
public void reInit() {
connect();
}
/**
* 连接
*/
private void connect() {
if (mqttAndroidClient != null && mqttAndroidClient.isConnected()) return;
MqttConnectOptions mqttConnectOptions = new MqttConnectOptions();
mqttConnectOptions.setUserName(USERNAME);
mqttConnectOptions.setPassword(PASSWORD.toCharArray());
mqttConnectOptions.setCleanSession(false); // 不清理离线消息。qos=1的消息，在设备离线期间会保存在云端。
mqttConnectOptions.setAutomaticReconnect(false); //本demo关闭自动重连。强烈建议生产环境开启自动重连。
mqttConnectOptions.setKeepAliveInterval(300);
/* 创建MqttAndroidClient对象, 并设置回调接口 */
mqttAndroidClient = new MqttAndroidClient(mContext, HOST, DeviceUuidFactory2.getDeviceUuidStr(mContext));
mqttAndroidClient.setCallback(new MqttCallback() {
@Override
public void connectionLost(Throwable cause) {
Log.i(TAG, "connection lost");
}
@Override
public void messageArrived(String topic, MqttMessage message) throws Exception {
Log.i(TAG, "topic: " + topic + ", msg: " + new String(message.getPayload()));
}
@Override
public void deliveryComplete(IMqttDeliveryToken token) {
Log.i(TAG, "msg delivered");
}
});
/* Mqtt建连 */
try {
mqttAndroidClient.connect(mqttConnectOptions, null, new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
Log.i(TAG, "connect succeed");
//自动订阅
subscribeTopic(SUB_TOPIC);
}
@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
Log.i(TAG, "connect failed");
}
});
} catch (MqttException e) {
e.printStackTrace();
}
}