Firebase 存储下载多张照片网址

Question

我有一个包含照片的 Firebase 存储。 我正在按名称1、2、3等组织照片...... 我正在尝试获取所有照片的下载 URL，因此将来我会将它们输入到 URL 的 Arraylist 中并使用 Glide 将它们呈现在照片库中（这就是我只寻找 URL 的原因）

我正在寻找一种方法，该方法仅在调用 onSucsess 时才会继续给我 Urls，当调用 onFailure 时（因为没有更多照片）我希望循环结束。

我正在尝试使用 Firebase 的 getDownloadUrl 方法并添加了一个布尔值，当调用 onFailure 时将触发 false。 并增加我从 1 开始的 photoOrder int，这样会改变所选照片的​​路径。

public class Photopackges extends AppCompatActivity {

public static boolean shouldRun = true;
public static final String TAG = "debug";
public static int photoOrder = 1;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_photopackges);

    //just normal firebase setup
    FirebaseStorage storage = FirebaseStorage.getInstance();


     // while shouldRun boolean is true keep going , until it will be defined false
    while (shouldRun == true) {

          // define my Firebase storage path,which contain one folder called "test" and three photos 1.jpg,2.jpg,3.jpg
         // the number of the photo is represented in the photoOrder int.
        String storagePath = "test/" + String.valueOf(photoOrder) + ".jpg";
        StorageReference ref = storage.getReference().child(storagePath);

        try {

            ref.getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                @Override
                public void onSuccess(Uri uri) {

                    // trying to define that if the action was successful , keep on going.
                    shouldRun = true;
                    Log.e(TAG, "sucsess! " + uri);


                }
            }).addOnFailureListener(new OnFailureListener() {
                @Override
                public void onFailure(@NonNull Exception e) {

                    // trying to define that if the action has failed , stop.
                    shouldRun = false;
                    Log.e(TAG, "Fail! " + e);
                }
            });


        } catch (Exception e) {
            Log.e(TAG, "Error! " + e);
            break;


        }

        //increment the photoOrder so it will go to the next path.
        photoOrder++;
        Log.e(TAG,"value of photoOrder "+photoOrder);
    }
}
}

日志 -

Loginfo

我不认为他在得到答案之前发送了更多请求。 我只需要他在事情发生时停下来

StorageException：该位置不存在对象。

我猜一定有一种更简单的方法可以使用 firebase 获取所有存储空间。

感谢您的帮助！

Answer 1

好的，经过大量尝试，我能够使用 wait() 和 notify() 方法。

现在我可以获取 ArrayList 以及我的 FirebaseStorage 中所有照片的 下载 URLS，其中可能包含未知数量的照片。 请注意，这只是因为我必须在将它们输入到我的存储中之前将它们重命名为 (1,2,3...etc)。

为此，您需要：

1. 设置 FirebaseStorage。
   1. 创建一个文件夹（我的称为 test）并填充图像。

我能够得到这个 Logcat，这正是我想要的 See Log

public static final String TAG = "eyaldebug";
public static PathGenerator pathGenerator;
public static ArrayList<String>photoURLs;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_photopackges);

    //Initialize the whole process

    photoURLs = new ArrayList<>();

    pathGenerator = new PathGenerator();

    new UrlProducer(pathGenerator);


}


/**
 * This class contains the GeneratePaths method,which responsible
 * of making new paths.
 * Also we have a simple set - get methods of the booleans.
 */

class PathGenerator {
    //start photo number
    int photoNumber = 0;
    //boolean that indicates if the path has been used already or not.
    boolean pathIsTaken = false;
    //our storage path.
    String path;

    /**
     * This method will generate a new path.
     * while path is taken , wait because we didn't use it yet.
     *
     * @param photoNumber
     */

    public synchronized String generatePath(int photoNumber) {

        while (pathIsTaken)
        {
            try {wait();} catch (Exception e) {}
        }
        this.photoNumber = photoNumber;
        path = "test/" + String.valueOf(photoNumber) + ".jpg";
        pathIsTaken = true;
        Log.e("eyaldebug", "path is :  " + path);
        return path;
    }

    /**
     * Simple set method.
     * @param value
     */

    public synchronized void setPathisSet(boolean value)
    {
        this.pathIsTaken = value;
    }

    /**
     * Unfreeze the thread, we call this method after onSucsess.
     */

    public synchronized void unfreeze( )
    {
        notifyAll();
    }

}


/**
 * Our URLProducer calls will take the paths,and will
 * send HTTP request to the storage that we'll get a
 * download URL returned.
 * later we'll be using Glide\Picasso to display those images.
 */

class UrlProducer implements Runnable {

    PathGenerator mPathGenerator;

    //initialize a String type ArrayList which will contain our URLS.
    public  ArrayList<String>photoURLs = new ArrayList<>();

    //constructor that will be called in the activity
    public UrlProducer(PathGenerator mPathGenerator) {
        this.mPathGenerator = mPathGenerator;

        Thread b = new Thread(this, "UrlProducer");
        b.start();
    }

    /**
     * Here we a simple download URL method using FirebaseStorage.
     * for the documentation for FirebaseStoarge download go to :
     *
     * https://firebase.google.com/docs/storage/android/download-files
     *
     * IF the task was successful we UNfreeze the threads so it will
     * keep sending us new URLS.
     * IF the onFailure was called the stroage is must likely empty and
     * we should stop trying to get new photos.
     */

    @Override
    public void run() {


        int photoNumber =0 ;

        while (true) {


            photoNumber ++;

            try {
                FirebaseStorage storage = FirebaseStorage.getInstance();
                StorageReference ref = storage.getReference();


                ref.child(pathGenerator.generatePath(photoNumber)).getDownloadUrl().addOnSuccessListener(new OnSuccessListener<Uri>() {
                    @Override
                    public void onSuccess(Uri uri) {

                        Log.e(TAG, "Success! " + uri);

                        //add the URL into the ArrayList
                        photoURLs.add(String.valueOf(uri));

                       //tell the generate method that the path has been used.
                        pathGenerator.setPathisSet(false);

                        //Unfreeze the thread so it will continue generate new paths.
                        pathGenerator.unfreeze();

                    }
                }).addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {

                        //When onFailure is called shutdown,and output the given ArrayList.

                        Log.e(TAG,"onFailure was called , storage is empty!");
                        Log.e(TAG,"----------------------------------------");
                        for(String singleUrl :photoURLs)
                        {
                            Log.e(TAG,""+singleUrl)   ;
                        }
                    }
                });


            }catch (Exception e){e.printStackTrace();}


        }
    }

}

Answer 2

嗯，问题是由于调用 ref.getDownloadUrl() 是异步的。因此，当您的第一个 onFailure 方法被调用时，已经有许多其他对异步方法的调用，因为您的循环运行得更快并且不等待前一个调用的响应。

所以我的建议是，您应该将 URL 存储在 Firebase RealtimeDatabase 中并获取这些 URL，然后使用 glide 加载它们。

如果您想了解如何处理 URL 列表，可以查看文档 https://firebase.google.com/docs/database/android/lists-of-data