我当前在我的android应用程序中使用MQTT协议，当我的应用程序打开或在后台运行时，我能够接收消息，但是当我完全关闭我的应用程序时，连接丢失，并且我不再能够接收消息。我需要仍然能够接收消息，因为我希望消息触发我的应用程序中的活动启动。这是我用来实现MQTT的文件。 MQTTHelper类：编辑。香港专业教育学院试图实现一项服务，但它似乎仍然无法正常工作。有人知道我在做什么错吗？
package com.example.carcrashdetection.helpers;
import android.app.Service;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.wifi.WifiInfo;
import android.net.wifi.WifiManager;
import android.os.Handler;
import android.os.IBinder;
import android.util.Log;
import android.widget.Toast;
import org.eclipse.paho.android.service.MqttAndroidClient;
import org.eclipse.paho.client.mqttv3.DisconnectedBufferOptions;
import org.eclipse.paho.client.mqttv3.IMqttActionListener;
import org.eclipse.paho.client.mqttv3.IMqttDeliveryToken;
import org.eclipse.paho.client.mqttv3.IMqttToken;
import org.eclipse.paho.client.mqttv3.MqttCallback;
import org.eclipse.paho.client.mqttv3.MqttConnectOptions;
import org.eclipse.paho.client.mqttv3.MqttException;
import org.eclipse.paho.client.mqttv3.MqttMessage;
public class MqttHelper extends Service {
public MqttAndroidClient mqttAndroidClient;
BroadcastReceiver m_ScreenOffReceiver;
final String serverUri = "tcp://hairdresser.cloudmqtt.com:15767";
final String clientId = "CarCrashDetection";
final String subscriptionTopic = "Topic/+";
final String username = "username";
final String password = "password";
@Override
public void onCreate() {
super.onCreate();
registerReceiver();
new Thread(new Runnable() {
@Override
public void run() {
MqttHelper.this.connect();
}
}).start();
}
public MqttHelper(Context context){
mqttAndroidClient = new MqttAndroidClient(context, serverUri, clientId);
mqttAndroidClient.setCallback(new MqttCallback() {
public void connectComplete(boolean b, String s) {
}
@Override
public void connectionLost(Throwable throwable) {
}
@Override
public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception {
Log.w("Mqtt", mqttMessage.toString());
}
@Override
public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken) {
}
});
connect();
}
public void setCallback(MqttCallback callback) {
mqttAndroidClient.setCallback(callback);
}
private void connect(){
MqttConnectOptions mqttConnectOptions = new MqttConnectOptions();
mqttConnectOptions.setAutomaticReconnect(true);
mqttConnectOptions.setCleanSession(false);
mqttConnectOptions.setUserName(username);
mqttConnectOptions.setPassword(password.toCharArray());
try {
mqttAndroidClient.connect(mqttConnectOptions, null, new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
DisconnectedBufferOptions disconnectedBufferOptions = new DisconnectedBufferOptions();
disconnectedBufferOptions.setBufferEnabled(true);
disconnectedBufferOptions.setBufferSize(100);
disconnectedBufferOptions.setPersistBuffer(false);
disconnectedBufferOptions.setDeleteOldestMessages(false);
mqttAndroidClient.setBufferOpts(disconnectedBufferOptions);
subscribeToTopic();
}
@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
Log.w("Mqtt", "Failed to connect to: " + serverUri + exception.toString());
}
});
} catch (MqttException ex){
ex.printStackTrace();
}
}
private void subscribeToTopic() {
try {
mqttAndroidClient.subscribe(subscriptionTopic, 0, null, new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
Log.w("Mqtt","Subscribed!");
}
@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
Log.w("Mqtt", "Subscribed fail!");
}
});
} catch (MqttException ex) {
System.err.println("Exception whilst subscribing");
ex.printStackTrace();
}
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
//do something
return START_STICKY;
}
@Override
public IBinder onBind(Intent intent) {
return null;
}
private void registerReceiver(){
m_ScreenOffReceiver = new BroadcastReceiver(){
@Override
public void onReceive(final Context context, Intent intent){
//Log.d(TAG,"onReceive of Wifi_State_Change called");
if(intent.getAction().equals(WifiManager.WIFI_STATE_CHANGED_ACTION))
{
int wifiState = intent.getIntExtra(WifiManager.EXTRA_WIFI_STATE, WifiManager.WIFI_STATE_UNKNOWN);
if(wifiState != WifiManager.WIFI_STATE_ENABLED)
return;
final WifiManager wifiManager = (WifiManager) context.getApplicationContext().getSystemService(Context.WIFI_SERVICE);
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
WifiInfo wifiInfo = wifiManager.getConnectionInfo();
String ssid = wifiInfo.getSSID();
Toast.makeText(context, "active wifi:" + ssid, Toast.LENGTH_SHORT).show();
//You can connect to the your mqtt broker again:
connect();
}
}, 10000);
}
}
};
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(WifiManager.WIFI_STATE_CHANGED_ACTION);
registerReceiver(m_ScreenOffReceiver, intentFilter);
}
@Override
public void onDestroy() {
if(mqttAndroidClient!=null) {
/*unregisterResources is needed,otherwise receive this error:
has leaked ServiceConnection org.eclipse.paho.android.service.MqttAndroidClient*/
try {
mqttAndroidClient.unregisterResources();
mqttAndroidClient.close();
mqttAndroidClient.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
}
unregisterReceiver(m_ScreenOffReceiver);
m_ScreenOffReceiver = null;
super.onDestroy();
}
}
MainActivity
private void startMqtt(){
mqttHelper = new MqttHelper(getApplicationContext());
mqttHelper.setCallback(new MqttCallbackExtended(){
@Override
public void connectComplete(boolean b, String s) {
Toast.makeText(MainActivity.this, "connected ", Toast.LENGTH_SHORT).show();
}
public void connectionLost(Throwable throwable){
Toast.makeText(MainActivity.this,"Disconnected", Toast.LENGTH_SHORT).show();
}
public void messageArrived(String topic, MqttMessage mqttMessage) throws Exception{
Log.e("message ", String.valueOf(mqttMessage));
Toast.makeText(MainActivity.this, "Crash Occurred", Toast.LENGTH_SHORT).show();
Intent intent = new Intent(MainActivity.this, alert.class);
startActivity(intent);
}
public void deliveryComplete(IMqttDeliveryToken iMqttDeliveryToken){
}
});
}
我已经搜索了一段时间，但似乎找不到任何有效的方法。我认为这将是一个简单的解决方案，但它对我而言并不是。任何帮助将非常感激。
您的选择是实现一个服务器，该服务器将发送设备推送通知，然后您的应用可以在再次打开该消息时提取该消息。