我正在开发一个从服务器获取数据的应用程序，我有一个包含头视图的列表视图，我正在下载一个图像，完成后我想更新我的头视图，我该如何实现？
我也在更新我的项目，它们正在成功更新，但我不知道如何在适配器中获取我的头视图并更新它。。。
保留对列表视图标头中使用的文本视图的引用。
我假设你添加列表视图标题如下：
View header = getLayoutInflater().inflate(R.layout.list_header, null);
TextView headerText = (TextView) header.findViewById(R.id.my_textview);
headerText.setText("This is my header!");
myListView.addHeaderView(header);
一旦图像下载完成，您就可以使用一些接口/侦听器进行通知，然后更新文本视图。
private class DownloadFilesTask extends AsyncTask<URL, Integer, Long> {
protected Long doInBackground(URL... urls) {
int count = urls.length;
long totalSize = 0;
for (int i = 0; i < count; i++) {
totalSize += Downloader.downloadFile(urls[i]);
publishProgress((int) ((i / (float) count) * 100));
// Escape early if cancel() is called
if (isCancelled()) break;
}
return totalSize;
}
protected void onProgressUpdate(Integer... progress) {
setProgressPercent(progress[0]);
}
protected void onPostExecute(Long result) {
ListView listView = (ListView) findViewById(R.id.list);
View header = getLayoutInflater().inflate(R.layout.header, null);
listView.addHeaderView(header);
}
}
我希望这可以帮助你：）
我刚刚得到了一个解决方案，我在这里发帖，所以它对每个都很有用
我只是简单地在列表适配器的构造函数中发送headerView的引用，并在那里下载图像，并将那里的图像设置为其零索引项，即头视图
public class MainListViewAdapter extends ArrayAdapter<DataObjects>{
private int layoutResourceID;
private ArrayList<DataObjects> dataObjects;
private Context context;
private ListHolder listHolder;
private View headerView;
private Bitmap bitmap;
private Boolean flagBitmap = false;
public MainListViewAdapter(Context context, int layoutResourceID, ArrayList<DataObjects> objects, View headerView) {
super(context, layoutResourceID, objects);
this.layoutResourceID = layoutResourceID;
this.dataObjects = objects;
this.context = context;
this.headerView = headerView;
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB)
new DownloadImageTask(this.dataObjects.get(0).getImageURL()).executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, (Void[])null);
else
new DownloadImageTask(this.dataObjects.get(0).getImageURL()).execute();
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
View row = convertView;
listHolder = new ListHolder();
if(row == null) {
LayoutInflater inflater = ((Activity)context).getLayoutInflater();
row = inflater.inflate(layoutResourceID, parent, false);
row.setTag(listHolder);
} else {
listHolder = (ListHolder) row.getTag();
}
DataObjects list = dataObjects.get(position);
if(position == 0) {
ImageView imageViewHeader = (ImageView) headerView.findViewById(R.id.imageViewHeaderImage);
if(flagBitmap)
imageViewHeader.setImageBitmap(bitmap);
else
imageViewHeader.setImageResource(R.drawable.sample);
}
return row;
}
private class ListHolder {
TextView textViewDate;
ImageView imageViewMagazine;
Button buttonPreview, buttonDownload;
}
private class DownloadImageTask extends AsyncTask<Void, Void, Bitmap> {
private String URL;
public DownloadImageTask(String URL) {
this.URL = URL;
}
protected Bitmap doInBackground(Void... urls) {
Bitmap mIcon11 = null;
try {
InputStream in = new java.net.URL(URL).openStream();
mIcon11 = BitmapFactory.decodeStream(in);
} catch (Exception e) {
e.printStackTrace();
}
return mIcon11;
}
protected void onPostExecute(Bitmap result) {
if(result != null) {
setThumbBitmap(result);
setThumbAvailable(true);
}
}
public void setThumbBitmap(Bitmap thumbBitmap) {
bitmap = thumbBitmap;
}
public void setThumbAvailable(boolean thumbAvailable) {
flagBitmap = thumbAvailable;
}
}
}