我的listview上滚动速度很慢，有一些文字和图片缩略图，信息是由json webservice获得的。 这是我创建listview的类：
public class NoticiasFragment extends Fragment{
private static final String TAG = "NoticiasFragment";
private String resultado;
private List<HashMap<String, String>> mAndroidMapList = new ArrayList<>();
private ListView mListView;
@Nullable
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState){
View view = inflater.inflate(R.layout.noticias_tab, container, false);
/*ActionBar actionBar = ((AppCompatActivity)getActivity()).getSupportActionBar();
actionBar.setTitle("Noticias");
actionBar.setStackedBackgroundDrawable(new ColorDrawable(Color.parseColor("#FFFFFF")));*/
Noticia noticia = new Noticia();
try {
resultado = noticia.execute("some-url").get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
armarListaNoticias(resultado, inflater, container, view);
return view;
}
protected void armarListaNoticias(String resultado, LayoutInflater inflater, ViewGroup container, View view){
mListView = (ListView) view.findViewById(R.id.listaNoticias);
try {
JSONArray jArray = new JSONArray(resultado);
String titulo = null;
for(int i=0; i < jArray.length(); i++) {
JSONObject jObject = jArray.getJSONObject(i);
HashMap<String, String> map = new HashMap<>();
map.put("Thumbnail", jObject.getString("thumbnail_path"));
titulo = jObject.getString("preview_title");
if(titulo.length() > 58){
titulo = titulo.substring(0, 58) + "...";
}
map.put("Titulo", titulo);
map.put("Titulo_completo", jObject.getString("full_title"));
map.put("Thumbnail_path", jObject.getString("thumbnail_path"));
map.put("Descripcion", jObject.getString("full_text"));
map.put("Resumen", "Resumen");
mAndroidMapList.add(map);
}
} catch (JSONException e) {
}
ListAdapter adapter = new SimpleAdapter(getActivity(), mAndroidMapList, R.layout.noticia_row,
new String[] { "Titulo", "Resumen" },
new int[] { R.id.titulo, R.id.resumen }){
@Override
public View getView(int position, View convertView, ViewGroup parent){
// Get the current item from ListView
View view = super.getView(position,convertView,parent);
Bitmap bmp = null;
ImageView imageView = (ImageView)view.findViewById(R.id.thumbnail);
DescargaImagenes descargaImagenes = new DescargaImagenes();
try {
bmp = descargaImagenes.execute("image-url" + mAndroidMapList.get(position).get("Thumbnail")).get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
imageView.setImageBitmap(bmp);
//CAMBIAR FUENTE
TextView myTextView = (TextView)view.findViewById(R.id.titulo);
Typeface typeFace=Typeface.createFromAsset(getActivity().getAssets(),"fonts/TitilliumWeb-Regular.ttf");
myTextView.setTypeface(typeFace);
myTextView = (TextView)view.findViewById(R.id.resumen);
typeFace=Typeface.createFromAsset(getActivity().getAssets(),"fonts/TitilliumWeb-Regular.ttf");
myTextView.setTypeface(typeFace);
if(position % 2 == 1)
{
// Set a background color for ListView regular row/item
view.setBackgroundColor(Color.parseColor("#7F1010"));
}
else
{
// Set the background color for alternate row/item
view.setBackgroundColor(Color.parseColor("#9C1F1F"));
}
return view;
}
};
mListView.setAdapter(adapter);
mListView.setOnItemClickListener(new AdapterView.OnItemClickListener(){
@Override
public void onItemClick(AdapterView<?> adapterView, View view, int position, long id) {
HashMap registro = mAndroidMapList.get(position);
Intent i = new Intent(getActivity(), DetalleNoticia.class);
i.putExtra("datos", registro);
startActivity(i);
}
});
}
}
我不知道如何设置图像，所以我的想法是下载并使用我的列表设置图像，该列表已经有getView()方法下载的图像路径。我还是Android的新手，所以这是我能想到的第一件事。
如何提高效果？
答案 0 :(得分：3)
您可以使用Picasso图片下载库。它将以异步方式下载图像。所以它对应用程序性能会有好处。
示例：
Picasso.with(mContext).load("https://s3om/foodev/hotel/" + imageLocation).placeholder(R.drawable.ic_default_hotel).error(R.drawable.ic_default_hotel).into(holder.imageviewHotel);
了解更多information。
答案 1 :(得分：1)
首先你应该检查是否异步：
DescargaImagenes descargaImagenes = new DescargaImagenes();
try {
bmp = descargaImagenes.execute("https://aguilaammo.com.mx/public/" + mAndroidMapList.get(position).get("Thumbnail")).get();
} catch (InterruptedException e) {
e.printStackTrace();
} catch (ExecutionException e) {
e.printStackTrace();
}
第二个在这里，每次从适配器中的资产创建字体时，不建议这样做。：
TextView myTextView = (TextView)view.findViewById(R.id.titulo);
Typeface typeFace=Typeface.createFromAsset(getActivity().getAssets(),"fonts/TitilliumWeb-Regular.ttf");
myTextView.setTypeface(typeFace);
myTextView = (TextView)view.findViewById(R.id.resumen);
typeFace=Typeface.createFromAsset(getActivity().getAssets(),"fonts/TitilliumWeb-Regular.ttf");
myTextView.setTypeface(typeFace)
相反，你应该像这样替换字体的相对位置：
private View getView(int position, View convertView, ViewGroup parent) {
View v;
if (convertView == null) {
v = inflater.inflate(resource, parent, false);
TextView myTextView = (TextView)view.findViewById(R.id.titulo);
Typeface typeFace=Typeface.createFromAsset(getActivity().getAssets(),"fonts/TitilliumWeb-Regular.ttf");
myTextView.setTypeface(typeFace);
myTextView = (TextView)view.findViewById(R.id.resumen);
typeFace=Typeface.createFromAsset(getActivity().getAssets(),"fonts/TitilliumWeb-Regular.ttf");
myTextView.setTypeface(typeFace);
} else {
v = convertView;
}
// bindView(position, v);
// you type face bind create in here.
return v;
}
最后。我建议你使用RecyclerView。这非常有用。
答案 2 :(得分：0)
现在我们通常使用OkHttp + Retrofit从net获取数据。 Retrofit会将JSON String转换为JavaBean，因此您不需要操作JSONObject ...
然后，如果您想将网络图像加载到ImageView，您可以使用Glide或Picasso或Fresco等。
当您将图像加载到ListView或GridView中的ImageView时，您应该为它们设置ScrollListener，就像列表或网格滚动时一样，您可以暂停网络请求，然后在listview停止滚动后恢复网络请求。
Glide + OkHttp + Retrofit都可以从Github下载或导入你的模型。
答案 3 :(得分：0)