无法从 URL 加载图像

Question

我尝试从 URL 加载图像，但它不起作用。发生了两种不同的错误。当我放置以 www 开头的 URL 时，应用程序不会关闭但也不会加载图像，只显示白色 space。但是当 URL 以 http:// 开头时，应用程序关闭。

我用来加载图像的代码是下一个：

public class ThreadAdapter extends BaseAdapter {
    ArrayList<Threadx> data;
    LayoutInflater inflater;
    public ThreadAdapter(Context context, ArrayList<Threadx> data) {
        super();
        inflater = LayoutInflater.from(context);
        this.data = data;
    }

    @Override
    public int getCount() {
        return data.size();
    }

    @Override
    public Object getItem(int position) {
        return data.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }
    private static class ViewHolder {
        TextView tvSubject;
        TextView tvContent;
        ImageView imagen;
    }
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder = null;
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.list_row_thread, null);
            viewHolder = new ViewHolder();
            viewHolder.tvSubject = (TextView) convertView
                    .findViewById(R.id.tvSubject);
            viewHolder.tvContent = (TextView) convertView
                    .findViewById(R.id.tvContent);
            viewHolder.imagen = (ImageView) convertView
                    .findViewById(R.id.image);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }
        String subject = data.get(position).getSubject();
        String content = data.get(position).getContent();
        String imagen = data.get(position).getImagen();
        viewHolder.tvSubject.setText(subject);
        viewHolder.tvContent.setText(content);
        Bitmap bitmap = null;
        HttpURLConnection urlConnection = null;
        try {
            URL url = new URL("www.matrallune.com/images/imagen_corporativa.jpg");
            //bitmap = BitmapFactory.decodeStream((InputStream)new URL("www.matrallune.com/images/imagen_corporativa.jpg").getContent());
            //bitmap = BitmapFactory.decodeStream(url.openConnection().getInputStream());
            urlConnection = (HttpURLConnection) url.openConnection();
            InputStream is = urlConnection.getInputStream();
            bitmap = BitmapFactory.decodeStream(is);
        } catch (IOException e) {
            e.printStackTrace();
        }
        viewHolder.imagen.setImageBitmap(bitmap);
        return convertView;
    }
}

我尝试了不同的方法，正如您在代码中看到的那样，但它们都有相同的问题。我的意图是从变量 "imagen".

中捕获 URL

Answer 1

我猜你不见了urlConnection.connect();
将您的代码更改为：

    try {
            URL url = new URL("www.matrallune.com/images/imagen_corporativa.jpg");
            urlConnection = (HttpURLConnection) url.openConnection();
            urlConnection.connect();
            InputStream is = urlConnection.getInputStream();
            bitmap = BitmapFactory.decodeStream(is);
        } catch (IOException e) {
            e.printStackTrace();
        }

虽然不确定。

并且正如评论中所建议的那样，使用像 Picasso 这样的库是明智的。这很容易。只需集成并将代码更改为：

Picasso.with(context).load(url).into(imgView);

更新：尝试包括 connection.setDoInput(true); setUseCaches(false).

Answer 2

使用 Picaso Lib http://square.github.io/picasso/ 调用 Picasso.with(context).load("http://imageUrl/image.png").into(imageView);

Answer 3

使用这个问题>>

public class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
    private ImageView imageView;
    private Bitmap image;

    public DownloadImageTask(ImageView imageView) {
        this.imageView = imageView;
    }

    protected Bitmap doInBackground(String... urls) {
        String urldisplay = urls[0];
        try {
            InputStream in = new java.net.URL(urldisplay).openStream();
            image = BitmapFactory.decodeStream(in);
        } catch (Exception e) {
            image = null;
        }
        return image;
    }

    @SuppressLint("NewApi")
    protected void onPostExecute(Bitmap result) {
        if (result != null) {
            imageView.setImageBitmap(result);
        }
    }
}

现在调用你的代码：

public View getView(int position, View convertView, ViewGroup parent) {
    ViewHolder viewHolder = null;
    if (convertView == null) {
        conv`enter code here`ertView = inflater.inflate(R.layout.list_row_thread, null);
        viewHolder = new ViewHolder();
        viewHolder.tvSubject = (TextView) convertView
                .findViewById(R.id.tvSubject);
        viewHolder.tvContent = (TextView) convertView
                .findViewById(R.id.tvContent);
        viewHolder.imagen = (ImageView) convertView
                .findViewById(R.id.image);
        convertView.setTag(viewHolder);
    } else {
        viewHolder = (ViewHolder) convertView.getTag();
    }
    String subject = data.get(position).getSubject();
    String content = data.get(position).getContent();
    String imagen = data.get(position).getImagen();
    viewHolder.tvSubject.setText(subject);
    viewHolder.tvContent.setText(content);
    new DownloadImageTask(viewHolder.imagen).execute("www.matrallune.com/images/imagen_corporativa.jpg");
    return convertView;
}

Answer 4

通过 Picasso 加载图片就像说 123，你完成了

Picasso
.with(context) //Context 
.load("http://i.imgur.com/DvpvklR.png") //Can be Url,File..
.into(imageView)//The ImageView;

这只是正常加载，您可以在他们的 Documentation

中找到更多选项

根据你的代码

Picasso
    .with(context) //Context 
    .load("http://matrallune.com/images/imagen_corporativa.jpg") //Can be Url,File..
    .into(viewHolder.imagen)//The ImageView;

你只是想用上面的代码替换图像加载代码。

你的最终适配器

public class ThreadAdapter extends BaseAdapter {
    ArrayList<Threadx> data;
    LayoutInflater inflater;
    private Context mContext;

    public ThreadAdapter(Context mContext, ArrayList<Threadx> data) {
        super();
        inflater = LayoutInflater.from(context);
        this.data = data;
        this.mContext = mContext;
    }

    @Override
    public int getCount() {
        return data.size();
    }

    @Override
    public Object getItem(int position) {
        return data.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    private static class ViewHolder {
        TextView tvSubject;
        TextView tvContent;
        ImageView imagen;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder = null;
        if (convertView == null) {
            convertView = inflater.inflate(R.layout.list_row_thread, null);
            viewHolder = new ViewHolder();
            viewHolder.tvSubject = (TextView) convertView
                    .findViewById(R.id.tvSubject);
            viewHolder.tvContent = (TextView) convertView
                    .findViewById(R.id.tvContent);
            viewHolder.imagen = (ImageView) convertView
                    .findViewById(R.id.image);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }
        String subject = data.get(position).getSubject();
        String content = data.get(position).getContent();
        String imagen = data.get(position).getImagen();
        viewHolder.tvSubject.setText(subject);
        viewHolder.tvContent.setText(content);

        //Loading image
        Picasso
        .with(mContext) //Context 
        .load("http://matrallune.com/images/imagen_corporativa.jpg") //Can be Url,File..
        .into(viewHolder.imagen)//The ImageView;


        return convertView;
    }
}

如果您从片段初始化适配器，您应该将上下文作为 getActivity() 传递，或者您也可以在片段的 onAttach() 中初始化它。

如果您从 Activity 初始化适配器。你只是想通过 this.

正在初始化

来自 Activity

ThreadAdapter tAdapter = new ThreadAdapter(this,data);

来自碎片

ThreadAdapter tAdapter = new ThreadAdapter(getActivity(),data);

无法从 URL 加载图像

Can't load an image from URL

android

listview

imageview

android-listview

android-imageview