从URL中的自定义适配器加载图像的ListView（Android的工作室） [英] Loading image from URL in custom adapter for ListView (Android Studio)

问题描述

虽然位图似乎是获取正确的，变量userBitmap'将保持为空。当向上或向下滚动在我的平板电脑，不过，新的名单列将包含图片，但他们都是相同的，错误的。真的，真的很困惑。我已经尝试了许多不同的方法从网络上获得的图像。任何帮助是极大的AP preciated。

While the bitmap seems to be fetched right, the variable 'userBitmap' will remain null. When scrolling up or down on my tablet, though, new list rows will contain the pictures, but they're all the same and wrong. Really, really confused. I've tried a number of different methods getting an image from the web. Any help is greatly appreciated.

我的自定义适配器：

public class MessagesArrayAdapter extends ArrayAdapter<ChatData>
{
    Bitmap userBitmap;

public MessageArrayAdapter(Context context, List<ChatData> objects)
{
    super(context, 0, objects);
}

public View getView(int position, View convertView, ViewGroup parent)
{
    ChatCell chatCell = new ChatCell();

    LayoutInflater inflater = LayoutInflater.from(getContext());
    convertView = inflater.inflate(R.layout.cell_chat, parent, false);

    chatCell.usernameTextView = (TextView) convertView.findViewById(R.id.usernameTextView);
    chatCell.messageTextView = (TextView) convertView.findViewById(R.id.messageTextView);
    chatCell.userImageView = (ImageView) convertView.findViewById(R.id.userImageView);

    ChatData chatData = getItem(position);

    // Get user image from web
    new loadImageAsync().execute(chatData.avatarURL);

    chatCell.userImageView.setImageBitmap(userBitmap);
    chatCell.usernameTextView.setText(chatData.username);
    chatCell.messageTextView.setText(chatData.message);

    return convertView;
}



private static class ChatCell
{
    TextView usernameTextView;
    TextView messageTextView;
    ImageView userImageView;
}

private class loadImageAsync extends AsyncTask<String, Void, Double>{
    @Override
    protected Double doInBackground(String... params) {

        userBitmap = loadImage(params[0]);


        return null;
    }
}


public Bitmap loadImage(String str) {

    InputStream instream = null;
    try {
        HttpGet httpRequest = new HttpGet(URI.create(str));
        HttpClient httpclient = new DefaultHttpClient();
        HttpResponse response = (HttpResponse) httpclient.execute(httpRequest);
        HttpEntity entity = response.getEntity();
        BufferedHttpEntity bufHttpEntity = new BufferedHttpEntity(entity);
        instream = bufHttpEntity.getContent();
        Bitmap myBitmap = BitmapFactory.decodeStream(instream);

        return myBitmap;
    } catch (Exception e) {
        e.printStackTrace();
        return null;
    } finally {
        //close input
        if (instream != null) {
            try {
                instream.close();
            } catch (IOException ioex) {
                // Handle error
            }
        }
    }

}

}

推荐答案

为您解决问题最简单的方法是使用一些库，例如的毕加索。它不仅更容易使用，让你的code更容易阅读，而且prevents从内存溢出的例外，当图片太大了。加载图像，然后无所谓一行：

The easiest way to solve your problem is using some library, for example Picasso. It is not only easier to use and make your code easier to read, but also prevents you from OutOfMemory Exceptions, when images are too big. Loading image is then matter of one line:

Picasso.with(context)
.load(urlOfYourImage)
.resize(50, 50) // here you resize your image to whatever width and height you like
.into(imageView)

这篇关于从URL中的自定义适配器加载图像的ListView（Android的工作室）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！