Question

我有一个活动，允许用户选择约500张图像，然后转到下一个活动，这些图像将在RecyclerView中填充，我应该如何使其全部工作，以实现流畅的用户体验和更好的性能。

目前，我正在使用意图将图像作为位图进行传递。

我正在使用photopicker库进行照片选择，这里允许用户选择多个图像，所有选定图像的文件路径都存储在字符串Arraylist中，该字符串在活动的onActivityResult中返回，我将结果存储在下面名为mArray的mUserSelectedPhotos字符串数组中的代码可供参考。

PhotoPickingActivity.java

mPickImagesButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            PhotoPicker.builder()
                    .setPhotoCount(200)
                    .setShowCamera(true)
                    .setShowGif(true)
                    .setPreviewEnabled(true)
                    .start(ChoosePhotoBookImagesActivity.this, PhotoPicker.REQUEST_CODE);
        }
    });


   @Override protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);

    if (resultCode == RESULT_OK && requestCode == PhotoPicker.REQUEST_CODE) {
        if (data != null) {
            mUserSelectedPhotos =
                    data.getStringArrayListExtra(PhotoPicker.KEY_SELECTED_PHOTOS);
        }
    }
}

单击下一步按钮，用户选择的图像字符串数组列表将通过意图传递到下一个活动。

PhotoPickingActivity.java

 mNextButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intent = new Intent(PhotoPickingActivity.this, PhotoBookListViewActivity.class);
            intent.putStringArrayListExtra("USER_SELECTED_IMAGES", mUserSelectedPhotos);
            startActivity(intent);
        }
    });

在包含recyclerview的下一个活动中，我正在此活动中接收发送的意图，并且在意图中接收的数据是字符串的数组列表，其中包含用户在上一个活动中选择的图像的文件路径。 / p>

PhotoBookListViewActivity.java

Intent intent = getIntent();
mReceivedImageList = intent.getStringArrayListExtra("USER_SELECTED_IMAGES");

我正在阅读mReceivedImageList并将文件路径转换为位图，并将其存储在新的位图数组列表中。

PhotoBookListViewActivity.java

 final ArrayList<PhotoBookViewModel> bitmapImages = new ArrayList<PhotoBookViewModel>();

    for (int i = 0; i < mImageList.size(); i++) {
        mPhotoUrl = mImageList.get(i).toString();
        Bitmap myBitmap = BitmapFactory.decodeFile(mPhotoUrl);
        bitmapImages.add(new PhotoBookViewModel(myBitmap));
    }

将bitmapImages arraylist（这是位图图像的列表）传递给适配器。

PhotoBookListViewActivity.java

mPhotoBookViewAdapter = new PhotoBookViewAdapter(PhotoBookListViewActivity.this, bitmapImages);

mPhotoBookViewRecyclerView.setAdapter(mPhotoBookViewAdapter);

mPhotoBookViewRecyclerView.setLayoutManager(new LinearLayoutManager(PhotoBookListViewActivity.this, LinearLayoutManager.VERTICAL, false));

PhotoBookViewModel.java

import android.graphics.Bitmap;

public class PhotoBookViewModel {

private Bitmap mImageRes;

public PhotoBookViewModel(Bitmap imageRes) {
    this.mImageRes = imageRes;
}

public Bitmap getImageRes() {
    return mImageRes;
}
}

PhotoBookViewAdapter.java

public class PhotoBookViewAdapter extends RecyclerView.Adapter<PhotoBookViewAdapter.PhotoViewHolder> {

private ArrayList<PhotoBookViewModel> mData;
private LayoutInflater mLayoutInflater;
private View mImageItemView;
private ArrayList<String> mSelectedPhotos;
private Bitmap mBitmap;
private Context mContext;

public class PhotoViewHolder extends RecyclerView.ViewHolder {

    private ImageView mImageView;

    public PhotoViewHolder(@NonNull View itemView) {
        super(itemView);
        mImageView = itemView.findViewById(R.id.imageview);
    }

    public void setData(PhotoBookViewModel currentObj) {
        this.mImageView.setImageBitmap(currentObj.getImageRes());
    }
}

public PhotoBookViewAdapter(Context context, ArrayList<String> selectedPhotos) {
    this.mContext = context;
    this.mSelectedPhotos = selectedPhotos;
    mBitmap = BitmapFactory.decodeFile (mSelectedPhotos.get(0).toString());
}

public PhotoBookViewAdapter(Context context, ArrayList<PhotoBookViewModel> mData) {
    this.mData = mData;
    mLayoutInflater = LayoutInflater.from(context);
}

@NonNull
@Override
public PhotoViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
    mImageItemView = LayoutInflater.from(viewGroup.getContext())
            .inflate(R.layout.photo_book_view_image_item, viewGroup, false);
    PhotoViewHolder photoViewHolder = new PhotoViewHolder(mImageItemView);
    mContext = viewGroup.getContext();
    return photoViewHolder;
}

@Override
public void onBindViewHolder(@NonNull PhotoViewHolder photoViewHolder, int position) {
    PhotoBookViewModel currentObj = mData.get(position);
    photoViewHolder.setData(currentObj);;
}

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

}

如何有效地在RecyclerView中加载大量图像？

0 个答案: