Add support for notification channels for O preview

mobile/src/main/res/values/strings.xml

@@ -56,6 +56,7 @@
   <string name="udp_dns_summary">Forward all DNS requests to remote</string>
 
   <!-- notification category -->
+  <string name="service">Service</string>
   <string name="forward_success">Shadowsocks started.</string>
   <string name="invalid_server">Invalid server name</string>
   <string name="service_failed">Failed to connect the remote server</string>

mobile/src/main/scala/com/github/shadowsocks/ShadowsocksApplication.scala

@@ -24,11 +24,12 @@ import java.io.{File, FileOutputStream, IOException}
 import java.util.Locale
 
 import android.annotation.SuppressLint
-import android.app.Application
+import android.app.{Application, NotificationChannel, NotificationManager}
 import android.content._
 import android.content.res.Configuration
 import android.os.{Build, LocaleList}
 import android.preference.PreferenceManager
+import android.support.v4.os.BuildCompat
 import android.support.v7.app.AppCompatDelegate
 import android.util.Log
 import com.evernote.android.job.JobManager
@@ -154,6 +155,9 @@ class ShadowsocksApplication extends Application {
     JobManager.create(this).addJobCreator(DonaldTrump)
 
     TcpFastOpen.enabled(settings.getBoolean(Key.tfo, TcpFastOpen.sendEnabled))
+
+    if (BuildCompat.isAtLeastO) getSystemService(classOf[NotificationManager]).createNotificationChannel(
+      new NotificationChannel("service", getText(R.string.service), NotificationManager.IMPORTANCE_MIN))
   }
 
   def crashRecovery() {

mobile/src/main/scala/com/github/shadowsocks/ShadowsocksNotification.scala

@@ -28,6 +28,7 @@ import android.os.{Build, PowerManager}
 import android.support.v4.app.NotificationCompat
 import android.support.v4.app.NotificationCompat.BigTextStyle
 import android.support.v4.content.ContextCompat
+import android.support.v4.os.BuildCompat
 import com.github.shadowsocks.aidl.IShadowsocksServiceCallback.Stub
 import com.github.shadowsocks.utils.{Action, State, TrafficMonitor, Utils}
 
@@ -60,6 +61,7 @@ class ShadowsocksNotification(private val service: BaseService, profileName: Str
     .setContentIntent(PendingIntent.getActivity(service, 0, new Intent(service, classOf[MainActivity])
       .setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT), 0))
     .setSmallIcon(R.drawable.ic_stat_shadowsocks)
+    .setChannel("service")
   if (Build.VERSION.SDK_INT < 24) builder.addAction(R.drawable.ic_navigation_close,
     service.getString(R.string.stop), PendingIntent.getBroadcast(service, 0, new Intent(Action.CLOSE), 0))
   private lazy val style = new BigTextStyle(builder)
@@ -97,7 +99,9 @@ class ShadowsocksNotification(private val service: BaseService, profileName: Str
     show()
   } else if (forceShow) show()
 
-  def show(): Unit = service.startForeground(1, builder.build)
+  def show(): Unit =
+    if (BuildCompat.isAtLeastO) nm.startServiceInForeground(new Intent(service, service.getClass), 1, builder.build())
+    else service.startForeground(1, builder.build)
 
   def destroy() {
     if (lockReceiver != null) {