我们准备了一个带有服务的 Android 应用程序，该服务与我们的服务器保持MQTT 连接。该服务从其 onStartCommand 返回一个 *START_STICKY*，以便 Android 重新启动服务，以防它因资源短缺而终止服务。但问题是，该服务经常被 Android OS 杀死。它有时会在几秒钟内终止服务一次，即使设备上没有其他进程在运行（使用 2GB 内存）。为什么 Android 如此频繁地杀死我的服务？如何减少重启次数？我的服务应该尽可能少地被杀死，因为它断开了我的 tcp 连接并且客户端必须再次重新连接，从而在我们的服务器上造成相当大的负载。这段代码有什么问题？谢谢
public class GTAndroidMQTTService extends Service implements MqttCallback {
private void init() {
this.clientId = Settings.System.getString(getContentResolver(), Secure.ANDROID_ID);
}
@Override
@Deprecated
public void onStart(Intent intent, int startId) {
logger("onStart() called");
super.onStart(intent, startId);
}
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
logger("onStartCommand() called");
if (client == null) {
try {
init();
conOpt = new MqttConnectOptions();
conOpt.setCleanSession(false);
conOpt.setUserName("...");
conOpt.setPassword("...");
try {
char[] keystorePass = getString(R.string.keystorepass).toCharArray();
KeyStore keyStore = KeyStore.getInstance("BKS");
keyStore.load(getApplicationContext().getResources().openRawResource(R.raw.prdkey),
keystorePass);
TrustManagerFactory trustManagerFactory = TrustManagerFactory
.getInstance(KeyManagerFactory.getDefaultAlgorithm());
trustManagerFactory.init(keyStore);
KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory
.getDefaultAlgorithm());
kmf.init(keyStore, keystorePass);
SSLContext sslContext = SSLContext.getInstance("TLS");
sslContext.init(kmf.getKeyManagers(), trustManagerFactory.getTrustManagers(), null);
conOpt.setSocketFactory(sslContext.getSocketFactory());
} catch (Exception ea) {
}
client = new MqttClient(this.mqttURL, clientId, new MqttDefaultFilePersistence(folder));
client.setCallback(this);
conOpt.setKeepAliveInterval(this.keepAliveSeconds);
} catch (MqttException e) {
e.printStackTrace();
} catch (NoSuchAlgorithmException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
if (intent == null) {
Log.i("TAG", "Android restarted the service[START_STICKY]");
if (client != null) {
tryToEstablishConnection();
}
}
return START_STICKY;
}
public void unsubscribe(String topicName) throws MqttException {
try {
client.unsubscribe(topicName);
} catch (Exception e) {
Log.i("TAG", "Unsubscribing from topic \"" + topicName + "has failed: " + e.toString());
}
}
private void retry() {
try {
notifyUserWithServiceStatus("Status Changed", "Status", "Connecting");
client.connect(conOpt);
notifyUserWithServiceStatus("Status Changed", "Status", "User Connected #" + (++retrycnt));
} catch (Exception e) {
notifyUserWithServiceStatus("Status Changed", "Status", "Cannot Connect");
e.printStackTrace();
}
}
public void subscribe(String topicName, int qos) throws MqttException {
try {
client.subscribe(topicName, qos);
} catch (Exception e) {
}
}
public void disconnect() {
try {
client.disconnect();
} catch (MqttException e) {
e.printStackTrace();
}
}
@Override
public IBinder onBind(Intent intent) {
logger("onBind() called");
return null;
}
@Override
public void onCreate() {
logger("onCreate() called");
super.onCreate();
}
@Override
public void connectionLost(Throwable arg0) { // Connection lost
notifyUserWithServiceStatus("Status Changed", "Status", "Connection Lost!");
tryToEstablishConnection();
}
private void tryToEstablishConnection() {
if (!retrying) {
retrying = true;
new Thread(new Runnable() {
@Override
public void run() {
for (;;) {
try {
if (isOnline() && !isConnected()) {
retry();
Thread.sleep(RETRY_INTERVAL);
} else if (isConnected()) {
retrying = false;
break;
} else if (!isOnline()) {
retrying = false;
break;
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
}).start();
}
}
private class NetworkConnectionIntentReceiver extends BroadcastReceiver {
@Override
public void onReceive(Context ctx, Intent intent) {
PowerManager pm = (PowerManager) getSystemService(POWER_SERVICE);
WakeLock wl = pm.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, "MQTT");
wl.acquire();
if (isOnline() && !isConnected())
notifyUserWithServiceStatus("Status Changed", "Status", "Online but not connected");
else if (!isOnline())
notifyUserWithServiceStatus("Status Changed", "Status", "Connection Lost!");
tryToEstablishConnection();
wl.release();
}
}
private boolean isConnected() {
try {
return client.isConnected();
} catch (Exception e) {
return false;
}
}
private boolean isOnline() {
ConnectivityManager conMgr = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo i = conMgr.getActiveNetworkInfo();
if (i == null)
return false;
if (!i.isConnected())
return false;
if (!i.isAvailable())
return false;
return true;
}
@Override
public void onDestroy() {
logger("onDestroy() called");
try {
client.disconnect();
Log.i("TAG", "Service stopped");
} catch (MqttException e) {
e.printStackTrace();
}
super.onDestroy();
}
@Override
public void deliveryComplete(IMqttDeliveryToken arg0) {
// TODO Auto-generated method stub
}
}