android - android Grid View 中的滚动不流畅

Question

在我的 android 应用程序中，我正在从 API 加载图像。但是在网格视图中加载图像后，滚动不流畅。我正在使用异步线程来获取图像，这样它就不会阻塞 UI。

现在有任何提高滚动性能的建议。

Answer 1

在单独的线程中加载图像肯定会有所帮助，但是这里还有另一个重要的性能问题需要处理，那就是“视图可重用性”，一旦您在适配器中设置了图像，请确保您实际上是在重用提供的视图适配器的 getView 方法，并且每次调用该方法时都不会创建/膨胀新的 Layout(GridElement)，这通常是导致加载所有图像后滚动变慢的原因，有几种模式可用于解决此问题，您应该阅读有关 ViewHolder 的信息，这是解决此问题的最常见且易于使用的模式...

希望这可以帮助...

问候

Answer 2

getView() 方法的代码 {{{

@Override
        public View getView(final int position, View convertView, ViewGroup parent) {
                final HashMap<String, String> song = songsList.get(position);
                imageURL = song.get(VariablesList.TAG_ALBUM_IMAGE);
                View v = null;
                if (convertView != null)
                        v = convertView;
                else
                        v = inflater.inflate(R.layout.gridlayout_item, parent, false);
                final ImageView imageView = (ImageView) v.findViewById(R.id.icon_image);
                final Thread startAlbum = new Thread() {
                        public void run() {

                                imageView.setImageBitmap(AlbumList
                                                .LoadImagetoGridView(imageURL));

                                synchronized (this) {
                                        this.notifyAll();
                                }
                        }
                };

                synchronized (startAlbum) {
                        startAlbum.start();
                        try {
                                startAlbum.wait();
                        } catch (InterruptedException e) {
                                e.printStackTrace();
                        }
                }
                imageView.setOnClickListener(new View.OnClickListener() {
                        // @Override
                        public void onClick(View v) {
                                albumUrl = new StringBuffer(resources.getString(R.string.songsListURL));
                                String albumIndex = song.get("id");
                                albumName = (song.get("name"));
                                imageURL = song.get(VariablesList.TAG_ALBUM_IMAGE);
                                SongsList albumList = new SongsList(imageURL, albumUrl,
                                                albumName,albumIndex,resources);
                                Thread threadAlbumList = new Thread(albumList);
                                threadAlbumList.start();

                                synchronized (albumList) {
                                        try {
                                                albumList.wait();
                                        } catch (InterruptedException e) {
                                                e.printStackTrace();
                                        }
                                }
                                if (!NewMediaPlayer.mediaPlayer.isPlaying()) {
                                        HashMap<String, String> playingSong = NewMediaPlayer.selectedSongs
                                                        .get(0);
                                        if (playingSong != null) {
                                                String url = playingSong.get("songUrl");
                                                String songName = playingSong.get("songName");
                                                if (songName != null)
                                                        {
                                                         NewMediaPlayer.songTitleLabel.setText(albumName
                                                                        + " - " + songName);
                                                         NewMediaPlayer.songTitle.setText(albumName+"-"+songName);
                                                        }
                                                NewMediaPlayer.playSong(url);
                                        }
                                }
                        }
                });

                TextView itemAlbumName = (TextView) v.findViewById(R.id.icon_text);
                itemAlbumName.setText(song.get("name"));
                itemAlbumName.setOnClickListener(new View.OnClickListener() {
                        public void onClick(View v) {
                                HashMap<String, String> song = songsList.get(position);
                                String songIndex = song.get("id");
                                String albumName = (song.get("name"));
                                Intent in = new Intent(context, SongListActivity.class);
                                in.putExtra("albumIndex", songIndex);
                                in.putExtra("albumName", albumName);
                                in.putExtra("AlbumImage", song.get(VariablesList.TAG_ALBUM_IMAGE));
                                context.startActivity(in);
                        }
                });

                return v;
        }

}}}

Answer 3

与其花功夫使用通用图像加载器库。而且它的性能很好。在 onCreate 方法中 gridView.setAdapter(new ImageAdapter(this,ImagesArrayPath));

    private static class ImageAdapter extends BaseAdapter {
    private  final String[] IMAGE_URLS ;

    private LayoutInflater inflater;

    private DisplayImageOptions options;

    ImageAdapter(Context context,String source[]) {
        inflater = LayoutInflater.from(context);
        IMAGE_URLS=source;

        options = new DisplayImageOptions.Builder()
                .showImageOnLoading(R.mipmap.ico_place_holder)
                .showImageForEmptyUri(R.drawable.ic_empty)
                .showImageOnFail(R.drawable.ic_error)
                .cacheInMemory(true)
                .cacheOnDisk(true)
                .considerExifParams(true)
                .bitmapConfig(Bitmap.Config.RGB_565)
                .build();
    }



    @Override
    public int getCount() {
        return IMAGE_URLS.length;
    }

    @Override
    public Object getItem(int position) {
        return null;
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        final ViewHolder holder;
        View view = convertView;
        if (view == null) {
            view = inflater.inflate(R.layout.item_grid_image, parent, false);
            holder = new ViewHolder();
            assert view != null;
            holder.imageView = (ImageView) view.findViewById(R.id.image);
            holder.progressBar = (ProgressBar) view.findViewById(R.id.progress);
            view.setTag(holder);
        } else {
            holder = (ViewHolder) view.getTag();
        }

        ImageLoader.getInstance()
                .displayImage(IMAGE_URLS[position], holder.imageView, options, new SimpleImageLoadingListener() {
                    @Override
                    public void onLoadingStarted(String imageUri, View view) {
                        holder.progressBar.setProgress(0);
                        holder.progressBar.setVisibility(View.VISIBLE);
                    }

                    @Override
                    public void onLoadingFailed(String imageUri, View view, FailReason failReason) {
                        holder.progressBar.setVisibility(View.GONE);
                    }

                    @Override
                    public void onLoadingComplete(String imageUri, View view, Bitmap loadedImage) {
                        holder.progressBar.setVisibility(View.GONE);
                    }
                }, new ImageLoadingProgressListener() {
                    @Override
                    public void onProgressUpdate(String imageUri, View view, int current, int total) {
                        holder.progressBar.setProgress(Math.round(100.0f * current / total));
                    }
                });

        return view;
    }
}

static class ViewHolder {
    ImageView imageView;
    ProgressBar progressBar;
}

愿这对你有所帮助。享受编码。