listView优化

 @Override
 public View getView(int position, View convertView, ViewGroup parent) {
        Log.d("Adapter", "Position:" + position + " : " + String.valueOf(System.currentTimeMillis()));
        ViewHolder holder;
        if (convertView == null) {
               final LayoutInflater inflater = (LayoutInflater) mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
               convertView = inflater.inflate(R.layout.list_item_icon_text, null);
               holder = new ViewHolder();
              holder.icon = (ImageView) convertView.findViewById(R.id.icon);
              holder.text = (TextView) convertView.findViewById(R.id.text);
              convertView.setTag(holder);
        } else {
              holder = (ViewHolder) convertView.getTag();
        }
               holder.icon.setImageResource(R.drawable.icon);
               holder.text.setText(mData[position]);
               return convertView;
        }

        static class ViewHolder {
                ImageView icon;
                TextView text;
        }
 }