android - stub_image 显示在 recyclerview 中的通用图像加载器上

Question

我已经实现了通用图像加载器以在 recyclerview 中显示图像。它显示 stub_image。代码包含一个 fragment 及其适配器，在我添加 universal-image-loader 之前它可以正常工作。

代码如下:

fragment 类

public class FourthFragment extends Fragment {
    private DisplayImageOptions options;
    ImageLoader imageLoader;
    RecyclerView rv;
    RecyclerView.LayoutManager mLayoutManager;
    RecyclerView.Adapter mAdapter;
    String[] str = {"one","two","three","four"};
    int[] img = {R.mipmap.rio_one,R.mipmap.rio_two,R.mipmap.rio_three,R.mipmap.rio_four};

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

        try {
            rv = (RecyclerView) v.findViewById(R.id.recycler_view);
            rv.setHasFixedSize(true);
            mLayoutManager = new LinearLayoutManager(getContext());
            rv.setLayoutManager(mLayoutManager);

        } catch (Exception e) {
            e.printStackTrace();
            Log.e("some error", "" + e);
        }

        mAdapter = new RecyclerView_Adapter(getActivity(), R.layout.view_pager_card_view,str,img);
        rv.setAdapter(mAdapter);

        return v;
    }

RecyclerViewAdapter.class

private class RecyclerView_Adapter extends RecyclerView.Adapter<RecyclerView_Adapter.DataHolder> {
    String [] result;
    Activity activity;
    int layoutResourceId;
    int[] imgs;

    public RecyclerView_Adapter(FragmentActivity activity, int layoutResourceId, String [] result, int[] img) {
        this.layoutResourceId=layoutResourceId;
        this.activity=activity;
        this.result=result;
        this.imgs=img;
    }

    public class DataHolder extends RecyclerView.ViewHolder{
        protected TextView tv1;
        protected ImageView iv1;
        public DataHolder(View v){
            super(v);

            tv1=(TextView)v.findViewById(R.id.textview1);
            iv1=(ImageView)v.findViewById(R.id.icon);

        }
    }

    @Override
    public DataHolder onCreateViewHolder(ViewGroup v, int i) {
        View item = LayoutInflater.from(v.getContext()).inflate(R.layout.view_pager_card_view, v, false);
        return new DataHolder(item);
    }

    @Override
    public void onBindViewHolder(DataHolder holder, int position) {

        ImageLoaderConfiguration configBuilder = new ImageLoaderConfiguration.Builder(getContext())
                .threadPriority(Thread.NORM_PRIORITY - 2)
                .denyCacheImageMultipleSizesInMemory()
                .build();

        imageLoader = ImageLoader.getInstance();
        imageLoader.init(configBuilder);
        options = new DisplayImageOptions.Builder()
                .showStubImage(R.mipmap.stub_image) // STUB_IMAGE SHOWING
                .showImageForEmptyUri(R.mipmap.image_for_empty_url)
                .cacheInMemory(true)
                .cacheOnDisc(true)
                .build();

        holder.tv1.setText(result[position]);
        imageLoader.displayImage("mipmap://" + imgs[position], holder.iv1, options);
    }

    @Override
    public int getItemCount() {
        Log.e("LIST SIZE", "" + result.length);
        return imgs.length;
    }

}

Answer 1

It’s best practice to place your app icons in mipmap- folders (not the drawable- folders) because they are used at resolutions different from the device’s current density.

引用自 Google BlogPost Article .

Mipmap 文件夹基本上仅用于您的应用程序图标 (ic_launcher.png)，任何其他可绘制文件(如选择器、形状可绘制对象、其他图标等)应放在相应的可绘制文件夹中。