Android编程入门-第64天

PhotoGalleryFragment.java

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;


public class PhotoGalleryFragment extends Fragment {

    private static final String TAG = "PhotoGalleryFragment";

    private RecyclerView mPhotoRecyclerView;
    private List<GalleryItem> mItems = new ArrayList<>();

    public static PhotoGalleryFragment newInstance() {
        return new PhotoGalleryFragment();
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setRetainInstance(true);
        new FetchItemsTask().execute();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_photo_gallery, container, false);

        mPhotoRecyclerView = (RecyclerView) v.findViewById(R.id.photo_recycler_view);
        mPhotoRecyclerView.setLayoutManager(new GridLayoutManager(getActivity(), 3));

        setupAdapter();

        return v;
    }

    private void setupAdapter() {
        if (isAdded()) {
            mPhotoRecyclerView.setAdapter(new PhotoAdapter(mItems));
        }
    }

    private class PhotoHolder extends RecyclerView.ViewHolder {
        private TextView mTitleTextView;

        public PhotoHolder(View itemView) {
            super(itemView);

            mTitleTextView = (TextView) itemView;
        }

        public void bindGalleryItem(GalleryItem item) {
            mTitleTextView.setText(item.toString());
        }
    }

    private class PhotoAdapter extends RecyclerView.Adapter<PhotoHolder> {

        private List<GalleryItem> mGalleryItems;

        public PhotoAdapter(List<GalleryItem> galleryItems) {
            mGalleryItems = galleryItems;
        }

        @Override
        public PhotoHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {
            TextView textView = new TextView(getActivity());
            return new PhotoHolder(textView);
        }

        @Override
        public void onBindViewHolder(PhotoHolder photoHolder, int position) {
            GalleryItem galleryItem = mGalleryItems.get(position);
            photoHolder.bindGalleryItem(galleryItem);
        }

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

    private class FetchItemsTask extends AsyncTask<Void,Void,List<GalleryItem>> {
        @Override
        protected List<GalleryItem> doInBackground(Void... params) {
            return new FlickrFetchr().fetchItems();
        }

        @Override
        protected void onPostExecute(List<GalleryItem> items) {
            mItems = items;
            setupAdapter();
        }
    }
}