fix: crashes when app in foreground and try to show downing progress …

…notification (#26)

demos/main/src/main/AndroidManifest.xml

@@ -41,7 +41,7 @@
       android:largeHeap="true"
       android:allowBackup="false"
       android:supportsRtl="true"
-      android:name="androidx.multidex.MultiDexApplication"
+      android:name=".DemoApplication"
       tools:targetApi="29">
 
     <activity android:name=".SampleChooserActivity"

demos/main/src/main/java/androidx/media3/demo/main/DemoApplication.java

@@ -0,0 +1,71 @@
+package androidx.media3.demo.main;
+
+import android.app.Activity;
+import android.os.Bundle;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.annotation.OptIn;
+import androidx.media3.common.util.UnstableApi;
+import androidx.multidex.MultiDexApplication;
+
+public final class DemoApplication extends MultiDexApplication {
+
+  @Override
+  public void onCreate() {
+    super.onCreate();
+    registerActivityLifecycleCallbacks(new ActivityLifecycleCallbacks() {
+      private int started = 0;
+      private int resumed = 0;
+      private int stopped = 0;
+
+      private boolean isAppBackFromBackground() {
+        return started == stopped + 1 && stopped > 0 && resumed == started;
+      }
+
+      private boolean isAppEnterBackground() {
+        return stopped == started;
+      }
+
+      @Override
+      public void onActivityStarted(@NonNull Activity activity) {
+        ++started;
+      }
+
+      @OptIn(markerClass = UnstableApi.class)
+      @Override
+      public void onActivityResumed(@NonNull Activity activity) {
+        ++resumed;
+        if (isAppBackFromBackground()) {
+          DemoDownloadService.sendRefreshForeground(activity, DemoDownloadService.class);
+        }
+      }
+
+      @Override
+      public void onActivityStopped(@NonNull Activity activity) {
+        ++stopped;
+        resumed = started;
+        if (isAppEnterBackground()) {
+          // app enter background
+        }
+      }
+
+      @Override
+      public void onActivityCreated(@NonNull Activity activity,
+          @Nullable Bundle savedInstanceState) {
+      }
+
+      @Override
+      public void onActivityPaused(@NonNull Activity activity) {
+      }
+
+      @Override
+      public void onActivitySaveInstanceState(@NonNull Activity activity,
+          @NonNull Bundle outState) {
+      }
+
+      @Override
+      public void onActivityDestroyed(@NonNull Activity activity) {
+      }
+    });
+  }
+}

libraries/exoplayer/src/main/java/androidx/media3/exoplayer/offline/DownloadService.java

@@ -18,12 +18,14 @@
 import static androidx.media3.exoplayer.offline.Download.STOP_REASON_NONE;
 
 import android.annotation.SuppressLint;
+import android.app.ForegroundServiceStartNotAllowedException;
 import android.app.Notification;
 import android.app.NotificationManager;
 import android.app.Service;
 import android.content.Context;
 import android.content.Intent;
 import android.content.pm.ServiceInfo;
+import android.os.Build;
 import android.os.Handler;
 import android.os.IBinder;
 import android.os.Looper;
@@ -149,6 +151,13 @@ public abstract class DownloadService extends Service {
   public static final String ACTION_SET_REQUIREMENTS =
       "androidx.media3.exoplayer.downloadService.action.SET_REQUIREMENTS";
 
+  /**
+   * Sets the service to foreground and show the downloading notification,
+   *  if the service is not foreground but has downloading item.
+   */
+  public static final String ACTION_REFRESH_FOREGROUND =
+      "androidx.media3.exoplayer.downloadService.action.REFRESH_FOREGROUND";
+
   /** Key for the {@link DownloadRequest} in {@link #ACTION_ADD_DOWNLOAD} intents. */
   public static final String KEY_DOWNLOAD_REQUEST = "download_request";
 
@@ -415,6 +424,19 @@ public static Intent buildSetRequirementsIntent(
         .putExtra(KEY_REQUIREMENTS, requirements);
   }
 
+  /**
+   * Builds an {@link Intent} for refreshing the service foreground state.
+   *
+   * @param context A {@link Context}.
+   * @param clazz The concrete download service being targeted by the intent.
+   * @return The created intent.
+   */
+  public static Intent buildRefreshForegroundIntent(
+      Context context,
+      Class<? extends DownloadService> clazz) {
+    return getIntent(context, clazz, ACTION_REFRESH_FOREGROUND);
+  }
+
   /**
    * Starts the service if not started already and adds a new download.
    *
@@ -543,6 +565,19 @@ public static void sendSetRequirements(
     startService(context, intent, foreground);
   }
 
+  /**
+   * Starts the service if not started already and refresh the foreground state.
+   *
+   * @param context A {@link Context}.
+   * @param clazz The concrete download service to be started.
+   */
+  public static void sendRefreshForeground(
+      Context context,
+      Class<? extends DownloadService> clazz) {
+    Intent intent = buildRefreshForegroundIntent(context, clazz);
+    startService(context, intent, false);
+  }
+
   /**
    * Starts a download service to resume any ongoing downloads.
    *
@@ -677,6 +712,9 @@ public int onStartCommand(@Nullable Intent intent, int flags, int startId) {
           downloadManager.setRequirements(requirements);
         }
         break;
+      case ACTION_REFRESH_FOREGROUND:
+        refreshForegroundNotification(downloadManager.getCurrentDownloads());
+        break;
       default:
         Log.e(TAG, "Ignored unrecognized action: " + intentAction);
         break;
@@ -823,6 +861,19 @@ private void notifyDownloadRemoved() {
     }
   }
 
+  private void refreshForegroundNotification(List<Download> downloads) {
+    if (foregroundNotificationUpdater != null
+        && !foregroundNotificationUpdater.periodicUpdatesStarted
+        && !isDestroyed) {
+      for (int i = 0; i < downloads.size(); i++) {
+        if (needsStartedService(downloads.get(i).state)) {
+          foregroundNotificationUpdater.startPeriodicUpdates();
+          break;
+        }
+      }
+    }
+  }
+
   /** Returns whether the service is stopped. */
   private boolean isStopped() {
     return isStopped;
@@ -912,21 +963,29 @@ public void invalidate() {
       }
     }
 
-    @SuppressLint("InlinedApi") // Using compile time constant FOREGROUND_SERVICE_TYPE_DATA_SYNC
     private void update() {
       DownloadManager downloadManager =
           Assertions.checkNotNull(downloadManagerHelper).downloadManager;
       List<Download> downloads = downloadManager.getCurrentDownloads();
       @RequirementFlags int notMetRequirements = downloadManager.getNotMetRequirements();
       Notification notification = getForegroundNotification(downloads, notMetRequirements);
       if (!notificationDisplayed) {
-        Util.setForegroundServiceNotification(
-            /* service= */ DownloadService.this,
-            notificationId,
-            notification,
-            ServiceInfo.FOREGROUND_SERVICE_TYPE_DATA_SYNC,
-            "dataSync");
-        notificationDisplayed = true;
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.S) {
+          try {
+            setForegroundServiceNotification(notification);
+          } catch (IllegalStateException e) {
+            if (!(e instanceof ForegroundServiceStartNotAllowedException)) {
+              throw e;
+            } else {
+              // Ignore app not in a valid state to start foreground service
+              // (e.g. started from bg)
+              Log.e(TAG, "app not in a valid state to start foreground service");
+              stopPeriodicUpdates();
+            }
+          }
+        } else {
+          setForegroundServiceNotification(notification);
+        }
       } else {
         // Update the notification via NotificationManager rather than by repeatedly calling
         // startForeground, since the latter can cause ActivityManager log spam.
@@ -938,6 +997,17 @@ private void update() {
         handler.postDelayed(this::update, updateInterval);
       }
     }
+
+    @SuppressLint("InlinedApi") // Using compile time constant FOREGROUND_SERVICE_TYPE_DATA_SYNC
+    private void setForegroundServiceNotification(Notification notification) {
+      Util.setForegroundServiceNotification(
+          /* service= */ DownloadService.this,
+          notificationId,
+          notification,
+          ServiceInfo.FOREGROUND_SERVICE_TYPE_DATA_SYNC,
+          "dataSync");
+      notificationDisplayed = true;
+    }
   }
 
   private static final class DownloadManagerHelper implements DownloadManager.Listener {