这是从 json 获取图像的 gridview。我成功地使用了它。但是当我从服务器获取它时，它有很多图像，这意味着所有图像都来自服务器。我想一次加载 12 张图像。
如何限制要加载的图像数量？
请简要帮助我，因为我对延迟加载视而不见。如果下面的代码还不够。这是完整的来源http://pastie.org/5583485
在这个 url 中，50 是要加载的图像数量，我可以通过这个值来限制图像的数量，无论我想要什么。但我只能加载一次，所以我不能加载更多。此 url 以 json 格式提供图像路径。
String url = "http://xxx.xxx.xxx/card/all/50/0/?token=57LzEsmBeykLbDCD04wTgK9WWV2XjJY0XBdqVU0HQvjIdu5EtTWOT1IQ1AYNwxt6Q5bG6FG73uvzLQSDGAIezwc8VcopEp0s63uzbdVgLSfts0TLmuVDOgyfn4lX";
asynctask 的 doInBackground
public class DownloadJSONFileAsync extends AsyncTask<String, Void, Void> {
protected void onPreExecute() {
super.onPreExecute();
showDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);
}
@Override
protected Void doInBackground(String... params) {
String url = "http://rest.mcolle.com/card/all/50/0/?token=57LzEsmBeykLbDCD04wTgK9WWV2XjJY0XBdqVU0HQvjIdu5EtTWOT1IQ1AYNwxt6Q5bG6FG73uvzLQSDGAIezwc8VcopEp0s63uzbdVgLSfts0TLmuVDOgyfn4lX";
JSONArray data = null;
try {
JSONObject jsonObject = new JSONObject(getJSONUrl(url));
MyArrList = new ArrayList<HashMap<String, Object>>();
HashMap<String, Object> map;
data = jsonObject.getJSONArray("data");
for (int i = 0; i < data.length(); i++) {
JSONObject c = data.getJSONObject(i);
map = new HashMap<String, Object>();
// Thumbnail Get ImageBitmap To Object
map.put("cardimage", (String) c.getString("cardimage"));
map.put("ImageThumBitmap",(Bitmap) loadBitmap(c.getString("cardimage")));
map.put("categoryid", (String) c.getString("categoryid"));
MyArrList.add(map);
}
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null;
}
protected void onPostExecute(Void unused) {
ShowAllContent(); // When Finish Show Content
dismissDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);
removeDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);
}
我显示图像的 ImageAdapter
public class ImageAdapter extends BaseAdapter {
private Context context;
private ArrayList<HashMap<String, Object>> MyArr = new ArrayList<HashMap<String, Object>>();
public ImageAdapter(Context c, ArrayList<HashMap<String, Object>> myArrList) {
context = c;
MyArr = myArrList;
}
public int getCount() {
return MyArr.size();
}
public Object getItem(int position) {
return position;
}
public long getItemId(int position) {
return position;
}
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder;
viewHolder = new ViewHolder();
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
if (convertView == null) {
convertView = inflater.inflate(R.layout.grid_item, null);
}
viewHolder.categoryCard = (ImageView) convertView.findViewById(R.id.category_card);
viewHolder.categoryCard.setImageResource(R.drawable.card_etc);
viewHolder.imageView = (ImageView) convertView.findViewById(R.id.imageView1);
try {
viewHolder.imageView.setImageBitmap((Bitmap) MyArr.get(position).get("ImageThumBitmap"));
} catch (Exception e) {
viewHolder.imageView.setImageResource(android.R.drawable.ic_menu_report_image);
}
return convertView;
}
}