Question

我正在尝试使用以下asynctask方法从网址加载图片（JPG）。

private class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
        ImageView bmImage;

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

        protected Bitmap doInBackground(String... urls) {
            String urldisplay = urls[0];
            Bitmap mIcon11 = null;
            try {
                InputStream in = new java.net.URL(urldisplay).openStream();
                mIcon11 = BitmapFactory.decodeStream(in);
            } catch (Exception e) {
                Log.e("Error", e.getMessage());
                e.printStackTrace();
            }
            return mIcon11;
        }

        protected void onPostExecute(Bitmap result) {
            bmImage.setImageBitmap(result);
        }
    }

我正在onCreate中执行此方法，就像这样

new DownloadImageTask((ImageView) findViewById(R.id.imageView1)).execute(final_url);

但是我看不到任何图像，当我调试它时，我发现mIcon11的值为null。我做错了什么

PS：final_url就像这样

www.website.com/somelink/IMG 005_153.JPG

Answer 1

你的finalurl http://www.website.com/somelink/IMG%20005_153.JPG没有返回任何东西。检查..

在使用之前尝试对其进行编码。

String uri = Uri.parse("http://...")
            .buildUpon()
            .appendQueryParameter("key", "val")
            .build().toString();

或尝试以下

String uri = URLEncoder.encode（finalurl，“utf-8”）;

Answer 2

private class ImageLoadTask extends AsyncTask<String, Void, Bitmap> {
        private Bitmap bitmap;

        @Override
        protected void onPreExecute() {
            // TODO Auto-generated method stub
            pb1.setVisibility(View.VISIBLE);
            super.onPreExecute();
        }

        @Override
        protected Bitmap doInBackground(String... params) {

            // TODO Auto-generated method stub
            try {
                URL url;
                url = new URL(params[0]);
                HttpURLConnection connection = (HttpURLConnection) url
                        .openConnection();
                connection.setDoInput(true);
                connection.connect();
                InputStream input = connection.getInputStream();
                bitmap = BitmapFactory.decodeStream(input);
            } catch (MalformedURLException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();

            }
            return bitmap;
        }

        @Override
        protected void onPostExecute(Bitmap result) {
            // TODO Auto-generated method stub
            super.onPostExecute(result);
            im.setImageBitmap(result);
            pb1.setVisibility(View.INVISIBLE);
        }
    }

并将其称为

new ImageLoadTask().execute(STRING URL);

从URL加载不起作用

2 个答案: