Merge pull request #390 from Oklahomawhore/master

Add automatic resume for unexpectedly killed works.

Author: hnvn

android/src/main/java/vn/hunghd/flutterdownloader/DownloadWorker.java

@@ -189,6 +189,14 @@ public Result doWork() {
         updateNotification(context, filename == null ? url : filename, DownloadStatus.RUNNING, task.progress, null, false);
         taskDao.updateTask(getId().toString(), DownloadStatus.RUNNING, task.progress);
 
+        //automatic resume for partial files. (if the workmanager unexpectedly quited in background)
+        String saveFilePath = savedDir + File.separator + filename;
+        File partialFile = new File(saveFilePath);
+        if (partialFile.exists()) {
+            isResume = true;
+            log("exists file for "+ filename + "automatic resuming...");
+        }
+
         try {
             downloadFile(context, url, savedDir, filename, headers, isResume);
             cleanUp();