Android：从Firebase存储下载文件列表

Question

I uploaded a file list to Firebase that I want to download using my app.

List<String> childsRef = new ArrayList<>();
childsRef.add("xxxx/img1");    
childsRef.add("xxxx/img2");
... etc

Then, through this list, I try to download files using my Firebase storageReference :

for (String child : childsRef) {
    islandRef = storageRef.child(child);
    File localFile = File.createTempFile("images", "jpg");
    islandRef.getFile(localFile).addOnSuccessListener(new OnSuccessListener<FileDownloadTask.TaskSnapshot>() {
       @Override
       public void onSuccess(FileDownloadTask.TaskSnapshot taskSnapshot) {
       // Local temp file has been created
       }
    }).addOnFailureListener(new OnFailureListener() {
       @Override
       public void onFailure(@NonNull Exception exception) {
       // Handle any errors
       }
 });
}

The download process is async, so I can't show pop-ups to visualize downloading progression... I want to navigate to next Activity only if all of pending downloads are done..

Do you have any ideas/help?

--EDIT Solution :

FirebaseStorage instance = FirebaseStorage.getInstance();
StorageReference referenceFromUrl = instance.getReferenceFromUrl("gs://xxxxxxx.appspot.com/");

for (final String aur : aurl) {
    final File localFile = new File(PATH + aur.substring(aur.lastIndexOf("/") + 1, aur.lastIndexOf(".")) + ".dat");

    StorageReference f = referenceFromUrl.child(aur);

    FileDownloadTask task = f.getFile(localFile);

    task.addOnSuccessListener(new OnSuccessListener<FileDownloadTask.TaskSnapshot>() {
        @Override
        public void onSuccess(FileDownloadTask.TaskSnapshot taskSnapshot) {
            size += localFile.length();
        }
    }).addOnFailureListener(new OnFailureListener() {
        @Override
        public void onFailure(@NonNull Exception exception) {
            Log.e("firebase ", ";local tem file not created  created " + exception.toString());
        }
    });

    while (!task.isComplete()) {
    }

    publishProgress("" + (int) ((float) i++ * 100 / aurl.length));

}

Answer 1

getFile returns a FileDownloadTask object, which is a subclass of Task . As you probably know, this Task tracks the progress of the download. You have the option of kicking off all the downloads at once, collecting all the Tasks in a list, then using Tasks.whenAll() to get a new Task that completes when all the downloads are complete.

I have a four part blog series about using Tasks that might help you better understand how they work.

Answer 2

make childsRef hashmap and add a boolean to see if download is completed. set value true when onSuccess and make a handler to send message when a download completed to check if all boolean values true. than start your activity from handler.