图像未显示在 firebase 的 recyclerview 中

Question

我正在尝试将图像从 firebase 获取到 recyclerview，但它没有显示我已将下载 URL 存储在模型类中，以便稍后检索它

这是recyclerview中没有图像的屏幕

这是实时数据截图

这些规则也适用于实时数据库和存储

Java 文件

Search_Fragment.java

 public class Search_Fragment extends Fragment {
    public List<Upload> mUploads;
    PostAdapter postsAdapter;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_search, container, false);
        RecyclerView postRecyclerView = view.findViewById(R.id.postRecyclerView);
        DatabaseReference databaseReference = FirebaseDatabase.getInstance().getReference("uploads");
        postRecyclerView.setLayoutManager(
                new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL)
        );
        mUploads = new ArrayList<>();
        postsAdapter = new PostAdapter(getContext(), mUploads);
        postRecyclerView.setAdapter(postsAdapter);

        //This are images that i tried manual ly and it worked fine
//        List<PostItem> postItems = new ArrayList<>();
//        postItems.add(new PostItem(R.drawable.image1));
//        postItems.add(new PostItem(R.drawable.image2));
//        postItems.add(new PostItem(R.drawable.image3));
//        postItems.add(new PostItem(R.drawable.image4));
//        postItems.add(new PostItem(R.drawable.image5));
//        postItems.add(new PostItem(R.drawable.image7));
        databaseReference.addValueEventListener(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot snapshot) {
                if (snapshot.exists()){
                    for (DataSnapshot dataSnapshot : snapshot.getChildren()) {
                        Upload upload = dataSnapshot.getValue(Upload.class);
                        Log.i("Sucess",upload.getmImageUrl());
                        mUploads.add(upload);

                }

                }
                else {
                    Toast.makeText(getContext(),"Failure",Toast.LENGTH_SHORT).show();
                }
                //notify the adapter
                postsAdapter.notifyDataSetChanged();
            }

            @Override
            public void onCancelled(@NonNull DatabaseError error) {
            }
        });
        return view;
    }
}

PostAdapter.Java //Apadter 类

public class PostAdapter extends RecyclerView.Adapter<PostAdapter.PostViewHolder> {
    public static List<Upload> mUploads;
    Context mcontext;


    public PostAdapter(Context context, List<Upload> uploads) {
        mUploads = uploads;
        mcontext = context;
    }


    @NonNull
    @Override
    public PostViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View view;
        view = LayoutInflater.from(mcontext).inflate(R.layout.post_item_container, parent, false);
        return new PostViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull PostViewHolder holder, int position) {
        Upload uploadCurrent = mUploads.get(position);
        Transformation transformation = new RoundedTransformationBuilder()
                .borderColor(Color.WHITE)
                .borderWidthDp(5)
                .cornerRadiusDp(13)
                .oval(false)
                .build();
        Log.i("sucess",uploadCurrent.getmImageUrl());
        Picasso.get()
                .load(uploadCurrent.getmImageUrl())
                .fit()
                .transform(transformation)
                .into(holder.postImageView);


    }

    @Override
    public int getItemCount() {
        return mUploads.size();
    }

    public static class PostViewHolder extends RecyclerView.ViewHolder {
        RoundedImageView postImageView;

        PostViewHolder(@NonNull View itemView) {
            super(itemView);
            postImageView = itemView.findViewById(R.id.imagePost);
        }

    }
}

Upload_Fragment.Java

public class Upload_Fragment extends Fragment {
    private static final int PICK_IMAGE_REQUEST = 10;
    private ImageView uploadImageView;
    private Uri mImageUri;
    private StorageReference storageReference;
    private DatabaseReference databaseReference;
    private StorageTask mUploadTask;

    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_upload, container, false);
        Button chooseImageButton = view.findViewById(R.id.upload_image_button);
        Button uploadImageButton = view.findViewById(R.id.done_button);
        uploadImageView = view.findViewById(R.id.upload_image_view);
        storageReference = FirebaseStorage.getInstance().getReference("uploads");
        databaseReference = FirebaseDatabase.getInstance().getReference("uploads");
        chooseImageButton.setOnClickListener(v -> openFileChooser());
        uploadImageButton.setOnClickListener(v -> {
            if (mUploadTask != null && mUploadTask.isInProgress()) {
                Toast.makeText(getActivity(), "Upload in Progress", Toast.LENGTH_SHORT).show();

            } else {
                uploadToFirebase(mImageUri);
            }


        });

        return view;
    }

    private void openFileChooser() {
        Intent intent = new Intent();
        intent.setType("image/*");
        intent.setAction(Intent.ACTION_GET_CONTENT);
        startActivityForResult(intent, PICK_IMAGE_REQUEST);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (requestCode == PICK_IMAGE_REQUEST && resultCode == RESULT_OK
                && data != null && data.getData() != null) {
            mImageUri = data.getData();
            Picasso.get().load(mImageUri).into(uploadImageView);

        }
    }

    private String getFileExtension(Uri uri) {

        ContentResolver contentResolver = Objects.requireNonNull(getActivity()).getContentResolver();
        MimeTypeMap mime = MimeTypeMap.getSingleton();
        return mime.getExtensionFromMimeType(contentResolver.getType(uri));
    }

    private void uploadToFirebase(Uri mImageUri) {
        if (mImageUri != null) {
            final ProgressDialog progressDialog = new ProgressDialog(getActivity());
            progressDialog.setTitle("Uploading...");
            progressDialog.show();

            StorageReference reference = storageReference.child(System.currentTimeMillis()
                    + "." + getFileExtension(mImageUri));
            reference.putFile(mImageUri)
                    .addOnSuccessListener(taskSnapshot -> {
                        progressDialog.dismiss();
                        Toast.makeText(getActivity(), "Saved Succesfully", Toast.LENGTH_SHORT).show();
                        reference.getDownloadUrl()
                                .addOnSuccessListener(uri -> {
                                    Upload upload = new Upload(uri.toString());
                                    String uploadId = databaseReference.push().getKey();
                                    databaseReference.child(uploadId).setValue(upload);
                                    Log.i("Link", uri.toString());
                                });
                    })
                    .addOnProgressListener(snapshot -> {
                        double progress = (100.0 * snapshot.getBytesTransferred() / snapshot
                                .getTotalByteCount());
                        progressDialog.setMessage("Uploaded " + (int) progress + "%");
                    })
                    .addOnFailureListener(e -> {
                        progressDialog.dismiss();
                        Toast.makeText(getActivity(), "Error Ocurred" + e.getMessage(), Toast.LENGTH_SHORT).show();
                    });


        }
    }
}

Upload.Java //模型类

public class Upload {
    private String mImageUrl;


    public Upload() {

    }

    public Upload(String imageUrl) {
        this.mImageUrl = imageUrl;
    }

    public String getmImageUrl() {
        return mImageUrl;
    }

    public void setmImageUrl(String mImageUrl) {
        this.mImageUrl = mImageUrl;
    }
}

Answer 1

看到要解决您的问题，它需要调试一些事情，然后只有您才能解决问题。此外，您需要澄清在什么时候发生了什么。您可以尝试以下事情以获得解决方案。

1..将Log 或Toast 放入for loop 中，同时将url 添加到mUploads 列表中。就像敬酒upload.getmImageUrl() 并检查它是否为您提供了正确的http 图像url。

2.Put Log 或 Toast 在 Picasso 的加载图像 url 之前。就像敬酒 uploadCurrent.getmImageUrl() 并检查它是否为您提供了正确的 http 图像 url。

如果在烘烤时发生错误，请将 toString(); 放在最后。之后，您将获得更好的想法来解决问题。

编辑： 在所有情况下，如果您获得正确的 url，那么问题在于 Picasso 库。您可以尝试 Glide 加载图像。为此添加

implementation 'com.github.bumptech.glide:glide:4.12.0'

annotationProcessor 'com.github.bumptech.glide:compiler:4.12.0'

然后像这样在onBindViewHolder边加载图片。

Glide.with(mContext).load(uploadCurrent.getmImageUrl()).into(holder.postImageView);

Answer 2

Picasso.get()
         .load(uploadCurrent.getmImageUrl())
         .fit()
         .transform(transformation)
         .into(holder.postImageView);

你可以试试这个……也许吧？

Picasso.with(holder.postImageView)//or context
        .load(uploadCurrent.getmImageUrl())
        .fit()
        .transform(transformation)
        .into(holder.postImageView);