DownloadDrawable.java

// Copyright 2009 Google Inc.
// Copyright 2011 NPR
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package org.npr.android.news;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;

import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

public class DownloadDrawable {
  private static final String LOG_TAG = DownloadDrawable.class.getName();

  public static Bitmap createBitmapFromUrl(String url) {
    Log.d(LOG_TAG, "Starting download");
    Bitmap bitmap;

    bitmap = readBitmapFromNetwork(url);

    Log.d(LOG_TAG, "Download complete");
    return bitmap;
  }


  /**
   * Convenience method to retrieve a bitmap image from
   * a URL over the network. The built-in methods do
   * not seem to work, as they return a FileNotFound
   * exception.
   *
   * Note that this does not perform any threading --
   * it blocks the call while retrieving the data.
   *
   * @param urlString The URL to read the bitmap from.
   * @return A Bitmap image or null if an error occurs.
   */
  private static Bitmap readBitmapFromNetwork(String urlString) {
    InputStream is = null;
    FlushedInputStream bis = null;
    Bitmap bmp = null;
    try {
      URL url = new URL(urlString);
      URLConnection conn = url.openConnection();
      conn.connect();
      is = conn.getInputStream();
      bis = new FlushedInputStream(is);
      bmp = BitmapFactory.decodeStream(bis);
    } catch (MalformedURLException e) {
      Log.e(LOG_TAG, "Bad image URL", e);
    } catch (IOException e) {
      Log.e(LOG_TAG, "Could not get remote image", e);
    } finally {
      try {
        if( is != null )
          is.close();
        if( bis != null )
          bis.close();
      } catch (IOException e) {
        Log.w(LOG_TAG, "Error closing stream.");
      }
    }
    Log.d(LOG_TAG, "Got bitmap");
    return bmp;
  }

  // This fixes the Image sometimes null bug
  // See http://android-developers.blogspot.com/2010/07/multithreading-for-performance.html
  static class FlushedInputStream extends FilterInputStream {
    public FlushedInputStream(InputStream inputStream) {
      super(inputStream);
    }

    @Override
    public long skip(long n) throws IOException {
      long totalBytesSkipped = 0L;
      while (totalBytesSkipped < n) {
        long bytesSkipped = in.skip(n - totalBytesSkipped);
        if (bytesSkipped == 0L) {
          int bytes = read();
          if (bytes < 0){
            break;  // we reached EOF
          } else {
            bytesSkipped = 1; // we read one byte
          }
        }
        totalBytesSkipped += bytesSkipped;
      }
      return totalBytesSkipped;
    }
  }
}