我阅读了Universal Image Loader,并制作了具有gridview的应用程序,并且此gridview从json获取了图像。但是我的应用程序加载速度太慢,因此我想使用Universal Image Loader,但是ImageAdapeter类中Universal Image Loader中的getView
函数像这样使用imageLoader.displayImage(imageUrls[position], imageView, options);
或用于公式imageLoader.displayImage(String, imageView, options);
因此,我没有字符串来完成此公式。我只是可以创建Object arr
来存储Arraylist。
如何将ArrayList<HashMap<String, Object>>
转换为字符串或以任何方式更改代码?
请确认或提出建议或向我推荐。易于阅读my code
这下面是我的ImageAdapter。它工作正常,但速度很慢。
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);
//==================== change area
Object arr = new ArrayList<HashMap<String, Object>>(); // make objec arr to store arraylist
arr = MyArr.get(position).get("categoryid");
if (arr.equals("1")) {
viewHolder.categoryCard.setImageResource(R.drawable.card_eat);
viewHolder.imageView = (ImageView) convertView.findViewById(R.id.imageView1);
} else {
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;
}
}
// Download JSON in Background
public class DownloadJSONFileAsync extends AsyncTask<String, Void, Void> {
String token = getIntent().getExtras().getString("token1");
protected void onPreExecute() {
super.onPreExecute();
showDialog(DIALOG_DOWNLOAD_JSON_PROGRESS);
}
@Override
protected Void doInBackground(String... params) {
String url = "http://xxx.xxx.xxx/card/all/20/0/?token="+token;
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);
}
}
这是来自Universal Image Loader的ImageAdapter
public class ImageAdapter extends BaseAdapter {
@Override
public int getCount() {
return imageUrls.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 ImageView imageView;
if (convertView == null) {
imageView = (ImageView) getLayoutInflater().inflate(R.layout.item_grid_image, parent, false);
} else {
imageView = (ImageView) convertView;
}
// I want to do like this
imageLoader.displayImage(imageUrls[position], imageView, options);
return imageView;
}
}
最佳答案
如果要保留ArrayList<HashMap<String, Object>>
,则必须通过以下方式创建新的String[]
:
String[] urls = new String[MyArrList.size()];
for(int i=0; i<MyArrList.size(); i++){
urls[i] = MyArrList.get(i).get("cardimage");
}
PS。我使用了您在代码中声明的变量名MyArrList,所以用大写字母开头的变量名并不是一个好主意。
PS2。我认为,如果您想使用Universal Image Loader,则可能不再需要将每个位图存储在HashMap中