无法显示已下载的图像

Question

我以前曾在SD卡中提取图像，并在列表视图中显示，使用：

imgView.setImageURI(Uri.parse(ImagePath));

现在，我正在尝试使用以下行显示来自URL的图像，但图像未显示在列表视图中，以下是使用的行：

imgView.setImageBitmap(getBitmapFromURL(ImagePath));

其中，getBitmapFromURL是：

public static Bitmap getBitmapFromURL(String src) {
        try {
            URL url = new URL(src);
            HttpURLConnection connection = (HttpURLConnection) url.openConnection();
            connection.setDoInput(true);
            connection.connect();
            InputStream input = connection.getInputStream();
            Bitmap myBitmap = BitmapFactory.decodeStream(input);
            return myBitmap;
            }
        catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }

没有显示异常，图像无法显示。

需要紧急解决方案......

谢谢，

Answer 1

这是一个同步加载。（就个人而言，如果要加载的图像数量太多，我会不会使用这个原因，应用程序有点滞后）..

URL url = new URL(//your URL);
Bitmap bmp = BitmapFactory.decodeStream(url.openConnection().getInputStream());
imageView.setImageBitmap(bmp);//your imageview

如果我是你，我会研究Async或懒惰的适配器..

修改 我忘记了我在哪里得到这些代码（非常感谢你有一位出色的代码作者）

这是

  public Bitmap getBitmap(String bitmapUrl) {
      try {
        URL url = new URL(bitmapUrl);
        return BitmapFactory.decodeStream(url.openConnection().getInputStream()); 
      }
      catch(Exception ex) {return null;}
    }

    public enum BitmapManager {
    INSTANCE;

    private final Map<String, SoftReference<Bitmap>> cache;
    private final ExecutorService pool;
    private Map<ImageView, String> imageViews = Collections
            .synchronizedMap(new WeakHashMap<ImageView, String>());
    private Bitmap placeholder;

    BitmapManager() {
        cache = new HashMap<String, SoftReference<Bitmap>>();
        pool = Executors.newFixedThreadPool(5);
    }

    public void setPlaceholder(Bitmap bmp) {
        placeholder = bmp;
    }

    public Bitmap getBitmapFromCache(String url) {
        if (cache.containsKey(url)) {
            return cache.get(url).get();
        }

        return null;
    }

    public void queueJob(final String url, final ImageView imageView,
            final int width, final int height) {
        /* Create handler in UI thread. */
        final Handler handler = new Handler() {
            @Override
            public void handleMessage(Message msg) {
                String tag = imageViews.get(imageView);
                if (tag != null && tag.equals(url)) {
                    if (msg.obj != null) {
                        imageView.setImageBitmap((Bitmap) msg.obj);
                    } else {
                        imageView.setImageBitmap(placeholder);
                        Log.d(null, "fail " + url);
                    }
                }
            }
        };

        pool.submit(new Runnable() {

            public void run() {
                final Bitmap bmp = downloadBitmap(url, width, height);
                Message message = Message.obtain();
                message.obj = bmp;
                Log.d(null, "Item downloaded: " + url);

                handler.sendMessage(message);
            }
        });
    }

    public void loadBitmap(final String url, final ImageView imageView,
            final int width, final int height) {
        imageViews.put(imageView, url);
        Bitmap bitmap = getBitmapFromCache(url);


        // check in UI thread, so no concurrency issues
        if (bitmap != null) {
            Log.i("inh","Item loaded from cache: " + url);
            imageView.setImageBitmap(bitmap);
        } else {
            imageView.setImageBitmap(placeholder);
            queueJob(url, imageView, width, height);
        }
    }

    private Bitmap downloadBitmap(String url, int width, int height) {
        try {
            Bitmap bitmap = BitmapFactory.decodeStream((InputStream) new URL(
                    url).getContent());

            bitmap = Bitmap.createScaledBitmap(bitmap, width, height, true);
            Log.i("nandi2 ako", ""+bitmap);
            cache.put(url, new SoftReference<Bitmap>(bitmap));
            return bitmap;
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }

}

现在称之为

String fbAvatarUrl = "//Your URL";

    BitmapManager.INSTANCE.loadBitmap(fbAvatarUrl, //Your ImageView, 60,60);
            //60 60 is my desired height and width 

Answer 2

之前我遇到过这种问题，你可以参考this thread，如果没有运气，试试我的代码，

 public static Bitmap loadImageFromUrl(String url) {
        URL m;
        InputStream i = null;
        BufferedInputStream bis = null;
        ByteArrayOutputStream out =null;
        try {
            m = new URL(url);
            i = (InputStream) m.getContent();
            bis = new BufferedInputStream(i,1024 * 8);
            out = new ByteArrayOutputStream();
            int len=0;
            byte[] buffer = new byte[1024];
            while((len = bis.read(buffer)) != -1){
                out.write(buffer, 0, len);
            }
            out.close();
            bis.close();
        } catch (MalformedURLException e1) {
            e1.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        byte[] data = out.toByteArray();    
        Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);        
        return bitmap;
    }