wifi断开并不会重新连接时，应用程序，服务和mqtt崩溃
我正在制作一个带有mqtt客户端和后台服务的应用程序，当我收到某些mqtt消息时会发出通知。
我使用Paho库和服务作为客户端，只要我连接到wifi并打开代理，一切都可以正常运行。
我不希望通过Internet访问代理，所以当没有wifi可用时，客户端将断开连接，问题是当wifi重新连接时，mqtt客户端将不会重新连接。
我已经尝试了很多事情，但是最新的测试是让处理程序检查是否有互联网以及是否通过wifi，如果是的话，我再次启动服务器" title="mqtt服务器">mqtt服务器。
我在清单中具有以下权限：
android.permission.INTERNET" android:name="android.permission.ACCESS_NETWORK_STATE"
android.permission.WAKE_LOCK"
当我运行模拟器并断开wifi连接时，整个应用以及服务均崩溃，并出现以下错误
这是我正在使用的处理程序：
handler.postDelayed(new Runnable(){ public void run(){
if (isWifiConnected()) {
startMqtt();
}
handler.postDelayed(this, delay);
}
}, delay);
这是isWifiConnected（如果没有Context context =
this;在应用程序中添加我，context.getSystemService将无法正常工作，我也不知道这是否也是一个问题）：
private boolean isWifiConnected() { boolean isWifi;
ConnectivityManager cm = (ConnectivityManager)context.getSystemService(Context.CONNECTIVITY_SERVICE);
NetworkInfo activeNetwork = cm.getActiveNetworkInfo();
boolean isConnected = activeNetwork != null && activeNetwork.isConnectedOrConnecting();
return isWifi = activeNetwork.getType() == ConnectivityManager.TYPE_WIFI;
}
D/AlarmPingSender: Unregister alarmreceiver to MqttServicephone
W/Mqtt: Failed to connect to: tcp://192.168.1.39:1883Unable to connect to server (32103) - java.net.ConnectException: failed to connect to /192.168.1.39 (port 1883) from /:: (port 0) after 30000ms: connect failed: ENETUNREACH (Network is unreachable)
I/chatty: uid=10085(com.iteda.nome) identical 85 lines
W/Mqtt: Failed to connect to: tcp://192.168.1.39:1883Unable to connect to server (32103) - java.net.ConnectException: failed to connect to /192.168.1.39 (port 1883) from /:: (port 0) after 30000ms: connect failed: ENETUNREACH (Network is unreachable)
W/Mqtt: Failed to connect to: tcp://192.168.1.39:1883Unable to connect to server (32103) - java.net.ConnectException: failed to connect to /192.168.1.39 (port 1883) from /:: (port 0) after 30000ms: connect failed: ENETUNREACH (Network is unreachable)
I/chatty: uid=10085(com.iteda.nome) identical 4 lines
W/Mqtt: Failed to connect to: tcp://192.168.1.39:1883Unable to connect to server (32103) - java.net.ConnectException: failed to connect to /192.168.1.39 (port 1883) from /:: (port 0) after 30000ms: connect failed: ENETUNREACH (Network is unreachable)
W/Mqtt: Failed to connect to: tcp://192.168.1.39:1883Unable to connect to server (32103) - java.net.ConnectException: failed to connect to /192.168.1.39 (port 1883) from /:: (port 0) after 30000ms: connect failed: ENETUNREACH (Network is unreachable)
I/chatty: uid=10085(com.iteda.nome) identical 36 lines
W/Mqtt: Failed to connect to: tcp://192.168.1.39:1883Unable to connect to server (32103) - java.net.ConnectException: failed to connect to /192.168.1.39 (port 1883) from /:: (port 0) after 30000ms: connect failed: ENETUNREACH (Network is unreachable)
W/Mqtt: Failed to connect to: tcp://192.168.1.39:1883Unable to connect to server (32103) - java.net.ConnectException: failed to connect to /192.168.1.39 (port 1883) from /:: (port 0) after 30000ms: connect failed: ENETUNREACH (Network is unreachable)
I/chatty: uid=10085(com.iteda.nome) identical 17 lines
W/Mqtt: Failed to connect to: tcp://192.168.1.39:1883Unable to connect to server (32103) - java.net.ConnectException: failed to connect to /192.168.1.39 (port 1883) from /:: (port 0) after 30000ms: connect failed: ENETUNREACH (Network is unreachable)
I/MqttConnection: Requesting Automatic reconnect using New Java AC
D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.iteda.nome, PID: 7394
java.lang.RuntimeException: Error receiving broadcast Intent { act=android.net.conn.CONNECTIVITY_CHANGE flg=0x4200010 (has extras) } in org.eclipse.paho.android.service.MqttService$NetworkConnectionIntentReceiver@5224905
at android.app.LoadedApk$ReceiverDispatcher$Args.lambda$getRunnable$0(LoadedApk.java:1401)
at android.app.-$$Lambda$LoadedApk$ReceiverDispatcher$Args$_BumDX2UKsnxLVrE6UJsJZkotuA.run(Unknown Source:2)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void java.util.Timer.cancel()' on a null object reference
at org.eclipse.paho.client.mqttv3.MqttAsyncClient.stopReconnectCycle(MqttAsyncClient.java:1120)
at org.eclipse.paho.client.mqttv3.MqttAsyncClient.reconnect(MqttAsyncClient.java:1057)
at org.eclipse.paho.android.service.MqttConnection.reconnect(MqttConnection.java:1049)
at org.eclipse.paho.android.service.MqttService.reconnect(MqttService.java:342)
at org.eclipse.paho.android.service.MqttService$NetworkConnectionIntentReceiver.onReceive(MqttService.java:827)
at android.app.LoadedApk$ReceiverDispatcher$Args.lambda$getRunnable$0(LoadedApk.java:1391)
at android.app.-$$Lambda$LoadedApk$ReceiverDispatcher$Args$_BumDX2UKsnxLVrE6UJsJZkotuA.run(Unknown Source:2)
at android.os.Handler.handleCallback(Handler.java:873)
at android.os.Handler.dispatchMessage(Handler.java:99)
at android.os.Looper.loop(Looper.java:193)
at android.app.ActivityThread.main(ActivityThread.java:6669)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)
I/Process: Sending signal. PID: 7394 SIG: 9
Application terminated.
我知道您可能需要更多信息，所以与其说我用错误的代码轰炸，不如告诉我您需要了解我做错的事情:)
错误代码似乎给出了答案，但是由于我是android和java的新手。我不知道如何更改方法以使其正确。
回答：
你说：
问题是，当wifi重新连接时，mqtt客户端将不会重新连接。
您可以
BroadcastReceiver在您的Service#onCreate()方法中仅使用a 来侦听WIFI_STATE_CHANGED_ACTION操作，如下所示。此外，你必须使用
return START_STICKY你的Service#onStartCommand()，这样应用程序被关闭后，在服务类将被运行。
public class MQTTService extends Service {private MqttAndroidClient clientPhone;
@Override
public void onCreate() {
super.onCreate();
registerReceiver();
new Thread(() -> init()).start();
}
@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(() -> {
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:
connectMQTT();
}, 10000);
}
}
};
IntentFilter intentFilter = new IntentFilter();
intentFilter.addAction(WifiManager.WIFI_STATE_CHANGED_ACTION);
registerReceiver(m_ScreenOffReceiver, intentFilter);
}
private void init() {
clientPhone = new MqttAndroidClient(this, "tcp://IP:PORT", "Your-CLIENT-ID");
//clientPhone = new MqttAndroidClient(this, "ssl://IP:PORT", "Your-CLIENT-ID");
clientPhone.setCallback(new MqttCallback() {
@Override
public void connectionLost(Throwable cause) {
//do something - for example reconnnect again
}
@Override
public void messageArrived(String topic, MqttMessage message) throws Exception {
//you can do everything with the received message from broker here
}
@Override
public void deliveryComplete(IMqttDeliveryToken token) {
//do something
}
});
}
private MqttConnectOptions getOptions(){
if(clientPhone.getServerURI().contains("ssl")) {
//set ssl config.for example:
//options.setSocketFactory(clientPhone.getSSLSocketFactory(YOUR_KEYSTORE_FILE, "YOUR_KEYSTORE_PASSWORD"));
//...
}
options.setKeepAliveInterval(...);
options.setMqttVersion(MqttConnectOptions.MQTT_VERSION_3_1_1);
options.setAutomaticReconnect(true);
options.setCleanSession(...);
//options.setWill(...);
options.setUserName(...));
options.setPassword(...);
return options;
}
private void connectMQTT() {
try {
//getOptions is a method that returns your MqttConnectOptions object
IMqttToken token = clientPhone.connect(getOptions());
token.setActionCallback(new IMqttActionListener() {
@Override
public void onSuccess(IMqttToken asyncActionToken) {
//do something
}
@SuppressWarnings("ThrowableResultOfMethodCallIgnored")
@Override
public void onFailure(IMqttToken asyncActionToken, Throwable exception) {
//do something
}
});
} catch (MqttException e) {
//do something
e.printStackTrace();
}
}
@Override
public void onDestroy() {
if(clientPhone!=null) {
/*unregisterResources is needed,otherwise receive this error:
has leaked ServiceConnection org.eclipse.paho.android.service.MqttAndroidClient*/
try {
clientPhone.unregisterResources();
clientPhone.close();
clientPhone.disconnect();
} catch (Exception e) {
e.printStackTrace();
}
}
unregisterReceiver(m_ScreenOffReceiver);
m_ScreenOffReceiver = null;
...
super.onDestroy();
}
}
必须声明
org.eclipse.paho.android.service.MqttService，并Your Service Class在您的清单文件：android:name="org.eclipse.paho.android.service.MqttService"
android:enabled="true" />
android:name="YOUR-MQTT-SERVICE-CLASS"
android:enabled="true"
android:exported="false" />
我希望这可以帮助你。
最好的祝愿
以上是 wifi断开并不会重新连接时，应用程序，服务和mqtt崩溃 的全部内容， 来源链接： utcz.com/qa/426715.html
