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我有一个带有图像的自定义列表视图。我需要通过 url 设置图像的来源，但我不希望进程阻塞 UI，所以我使用的是 Async 任务。但是，图像仅设置在列表中的一个图像上，并且显示为幻灯片。

有没有更好的方法来解决这个问题？

这是我的代码：

自定义适配器

class MyArrayAdapter extends ArrayAdapter<String> {

    private final Context context;
    private int i = 0;
    Contact[] myContact;
    String imageURL;

    public MyArrayAdapter(Context context, Contact[] contact) {
        super(context, R.layout.custom_list);
        this.context = context;
        this.myContact = contact;
        int s = myContact.length;
        int k = contact.length;
    }

    @Override
       public int getCount() {
           return myContact.length;
       }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        rowView = inflater.inflate(R.layout.custom_list, parent, false);
        TextView contact_first_name = (TextView) rowView
                .findViewById(R.id.first_name);
        TextView contact_last_name = (TextView) rowView
                .findViewById(R.id.last_name);
        imageView = (ImageView) rowView.findViewById(R.id.photo);
        imageURL = myContact[i].getImageUrl();          
        new LoadImageTask().execute(imageURL);

        contact_first_name.setText(myContact[i].getFirstName());
        contact_last_name.setText(myContact[i].getLastName());

        i++;

        return rowView;
    }       
}

异步任务

public class LoadImageTask extends AsyncTask<String, Integer, String> {

    Bitmap bitmap;

    @Override
    protected String doInBackground(String... imageURL) {
        // TODO Auto-generated method stub
        try {
              bitmap = BitmapFactory.decodeStream((InputStream)new URL(imageURL[0]).getContent());

            } catch (MalformedURLException e) {
              e.printStackTrace();
            } catch (IOException e) {
              e.printStackTrace();
            }
        return null;
    }

    protected void onPostExecute(String line) {

        try {
            imageView.setImageBitmap(bitmap);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}
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1 回答 1

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执行时传递 imageview 对象。
使用 setTag 传递 url。以下将解决您的问题，但我建议您仔细查看本教程。它将防止您出现内存不足和性能问题。

  @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        LayoutInflater inflater = (LayoutInflater) context
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        rowView = inflater.inflate(R.layout.custom_list, parent, false);
        TextView contact_first_name = (TextView) rowView
                .findViewById(R.id.first_name);
        TextView contact_last_name = (TextView) rowView
                .findViewById(R.id.last_name);
        imageView = (ImageView) rowView.findViewById(R.id.photo);
        imageURL = myContact[i].getImageUrl();
        imageView.setTag(imageURL);    // add this      
        new LoadImageTask().execute(imageView); // change here

        contact_first_name.setText(myContact[i].getFirstName());
        contact_last_name.setText(myContact[i].getLastName());

        i++;

        return rowView;
    }

在异步任务中：

public class LoadImageTask extends AsyncTask<ImageView, Integer, String> { // change here

    Bitmap bitmap;
   ImageView image = null; // add this

    @Override
    protected String doInBackground(String... imageURL) {
        // TODO Auto-generated method stub
    this.image = imageURL[0]; // add this
        String url = (String) image.getTag(); // add this

        try {
              bitmap = BitmapFactory.decodeStream((InputStream)new URL(url).getContent()); // change here

            } catch (MalformedURLException e) {
              e.printStackTrace();
            } catch (IOException e) {
              e.printStackTrace();
            }
        return null;
    }

    protected void onPostExecute(String line) {

        try {
            image.setImageBitmap(bitmap); // change here
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

这将解决您的问题。

于 2012-12-03T01:15:41.293 回答