samples/XmlAdapters/src/com/example/android/xmladapters/ImageDownloader.java - platform/development - Git at Google

 /*
  * Copyright (C) 2010 The Android Open Source Project
  *
  * 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 com.example.android.xmladapters;

 import org.apache.http.HttpEntity;
 import org.apache.http.HttpResponse;
 import org.apache.http.HttpStatus;
 import org.apache.http.client.methods.HttpGet;

 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.graphics.Color;
 import android.graphics.drawable.ColorDrawable;
 import android.graphics.drawable.Drawable;
 import android.net.http.AndroidHttpClient;
 import android.os.AsyncTask;
 import android.os.Handler;
 import android.util.Log;
 import android.widget.ImageView;

 import java.io.BufferedOutputStream;
 import java.io.ByteArrayOutputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.lang.ref.SoftReference;
 import java.lang.ref.WeakReference;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;

 /**
  * This helper class download images from the Internet and binds those with the provided ImageView.
  *
  * <p>It requires the INTERNET permission, which should be added to your application's manifest
  * file.</p>
  *
  * A local cache of downloaded images is maintained internally to improve performance.
  */
 public class ImageDownloader {
     private static final String LOG_TAG = "ImageDownloader";

     private static final int HARD_CACHE_CAPACITY = 40;
     private static final int DELAY_BEFORE_PURGE = 30 * 1000; // in milliseconds

     // Hard cache, with a fixed maximum capacity and a life duration
     private final static HashMap<String, Bitmap> sHardBitmapCache =
         new LinkedHashMap<String, Bitmap>(HARD_CACHE_CAPACITY / 2, 0.75f, true) {
         private static final long serialVersionUID = -7190622541619388252L;
         @Override
         protected boolean removeEldestEntry(Map.Entry<String, Bitmap> eldest) {
             if (size() > HARD_CACHE_CAPACITY) {
                 // Entries push-out of hard reference cache are transferred to soft reference cache
                 sSoftBitmapCache.put(eldest.getKey(), new SoftReference<Bitmap>(eldest.getValue()));
                 return true;
             } else {
                 return false;
             }
         }
     };

     // Soft cache for bitmap kicked out of hard cache
     private final static ConcurrentHashMap<String, SoftReference<Bitmap>> sSoftBitmapCache =
         new ConcurrentHashMap<String, SoftReference<Bitmap>>(HARD_CACHE_CAPACITY / 2);

     private final Handler purgeHandler = new Handler();

     private final Runnable purger = new Runnable() {
         public void run() {
             clearCache();
         }
     };

     /**
      * Download the specified image from the Internet and binds it to the provided ImageView. The
      * binding is immediate if the image is found in the cache and will be done asynchronously
      * otherwise. A null bitmap will be associated to the ImageView if an error occurs.
      *
      * @param url The URL of the image to download.
      * @param imageView The ImageView to bind the downloaded image to.
      */
     public void download(String url, ImageView imageView) {
         download(url, imageView, null);
     }

     /**
      * Same as {@link #download(String, ImageView)}, with the possibility to provide an additional
      * cookie that will be used when the image will be retrieved.
      *
      * @param url The URL of the image to download.
      * @param imageView The ImageView to bind the downloaded image to.
      * @param cookie A cookie String that will be used by the http connection.
      */
     public void download(String url, ImageView imageView, String cookie) {
         resetPurgeTimer();
         Bitmap bitmap = getBitmapFromCache(url);

         if (bitmap == null) {
             forceDownload(url, imageView, cookie);
         } else {
             cancelPotentialDownload(url, imageView);
             imageView.setImageBitmap(bitmap);
         }
     }

     /*
      * Same as download but the image is always downloaded and the cache is not used.
      * Kept private at the moment as its interest is not clear.
        private void forceDownload(String url, ImageView view) {
           forceDownload(url, view, null);
        }
      */

     /**
      * Same as download but the image is always downloaded and the cache is not used.
      * Kept private at the moment as its interest is not clear.
      */
     private void forceDownload(String url, ImageView imageView, String cookie) {
         // State sanity: url is guaranteed to never be null in DownloadedDrawable and cache keys.
         if (url == null) {
             imageView.setImageDrawable(null);
             return;
         }

         if (cancelPotentialDownload(url, imageView)) {
             BitmapDownloaderTask task = new BitmapDownloaderTask(imageView);
             DownloadedDrawable downloadedDrawable = new DownloadedDrawable(task);
             imageView.setImageDrawable(downloadedDrawable);
             task.execute(url, cookie);
         }
     }

     /**
      * Clears the image cache used internally to improve performance. Note that for memory
      * efficiency reasons, the cache will automatically be cleared after a certain inactivity delay.
      */
     public void clearCache() {
         sHardBitmapCache.clear();
         sSoftBitmapCache.clear();
     }

     private void resetPurgeTimer() {
         purgeHandler.removeCallbacks(purger);
         purgeHandler.postDelayed(purger, DELAY_BEFORE_PURGE);
     }

     /**
      * Returns true if the current download has been canceled or if there was no download in
      * progress on this image view.
      * Returns false if the download in progress deals with the same url. The download is not
      * stopped in that case.
      */
     private static boolean cancelPotentialDownload(String url, ImageView imageView) {
         BitmapDownloaderTask bitmapDownloaderTask = getBitmapDownloaderTask(imageView);

         if (bitmapDownloaderTask != null) {
             String bitmapUrl = bitmapDownloaderTask.url;
             if ((bitmapUrl == null) || (!bitmapUrl.equals(url))) {
                 bitmapDownloaderTask.cancel(true);
             } else {
                 // The same URL is already being downloaded.
                 return false;
             }
         }
         return true;
     }

     /**
      * @param imageView Any imageView
      * @return Retrieve the currently active download task (if any) associated with this imageView.
      * null if there is no such task.
      */
     private static BitmapDownloaderTask getBitmapDownloaderTask(ImageView imageView) {
         if (imageView != null) {
             Drawable drawable = imageView.getDrawable();
             if (drawable instanceof DownloadedDrawable) {
                 DownloadedDrawable downloadedDrawable = (DownloadedDrawable)drawable;
                 return downloadedDrawable.getBitmapDownloaderTask();
             }
         }
         return null;
     }

     /**
      * @param url The URL of the image that will be retrieved from the cache.
      * @return The cached bitmap or null if it was not found.
      */
     private Bitmap getBitmapFromCache(String url) {
         // First try the hard reference cache
         synchronized (sHardBitmapCache) {
             final Bitmap bitmap = sHardBitmapCache.get(url);
             if (bitmap != null) {
                 // Bitmap found in hard cache
                 // Move element to first position, so that it is removed last
                 sHardBitmapCache.remove(url);
                 sHardBitmapCache.put(url, bitmap);
                 return bitmap;
             }
         }

         // Then try the soft reference cache
         SoftReference<Bitmap> bitmapReference = sSoftBitmapCache.get(url);
         if (bitmapReference != null) {
             final Bitmap bitmap = bitmapReference.get();
             if (bitmap != null) {
                 // Bitmap found in soft cache
                 return bitmap;
             } else {
                 // Soft reference has been Garbage Collected
                 sSoftBitmapCache.remove(url);
             }
         }

         return null;
     }

     /**
      * The actual AsyncTask that will asynchronously download the image.
      */
     class BitmapDownloaderTask extends AsyncTask<String, Void, Bitmap> {
         private static final int IO_BUFFER_SIZE = 4 * 1024;
         private String url;
         private final WeakReference<ImageView> imageViewReference;

         public BitmapDownloaderTask(ImageView imageView) {
             imageViewReference = new WeakReference<ImageView>(imageView);
         }

         /**
          * Actual download method.
          */
         @Override
         protected Bitmap doInBackground(String... params) {
             final AndroidHttpClient client = AndroidHttpClient.newInstance("Android");
             url = params[0];
             final HttpGet getRequest = new HttpGet(url);
             String cookie = params[1];
             if (cookie != null) {
                 getRequest.setHeader("cookie", cookie);
             }

             try {
                 HttpResponse response = client.execute(getRequest);
                 final int statusCode = response.getStatusLine().getStatusCode();
                 if (statusCode != HttpStatus.SC_OK) {
                     Log.w("ImageDownloader", "Error " + statusCode +
                             " while retrieving bitmap from " + url);
                     return null;
                 }

                 final HttpEntity entity = response.getEntity();
                 if (entity != null) {
                     InputStream inputStream = null;
                     OutputStream outputStream = null;
                     try {
                         inputStream = entity.getContent();
                         final ByteArrayOutputStream dataStream = new ByteArrayOutputStream();
                         outputStream = new BufferedOutputStream(dataStream, IO_BUFFER_SIZE);
                         copy(inputStream, outputStream);
                         outputStream.flush();

                         final byte[] data = dataStream.toByteArray();
                         final Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);

                         // FIXME : Should use BitmapFactory.decodeStream(inputStream) instead.
                         //final Bitmap bitmap = BitmapFactory.decodeStream(inputStream);

                         return bitmap;

                     } finally {
                         if (inputStream != null) {
                             inputStream.close();
                         }
                         if (outputStream != null) {
                             outputStream.close();
                         }
                         entity.consumeContent();
                     }
                 }
             } catch (IOException e) {
                 getRequest.abort();
                 Log.w(LOG_TAG, "I/O error while retrieving bitmap from " + url, e);
             } catch (IllegalStateException e) {
                 getRequest.abort();
                 Log.w(LOG_TAG, "Incorrect URL: " + url);
             } catch (Exception e) {
                 getRequest.abort();
                 Log.w(LOG_TAG, "Error while retrieving bitmap from " + url, e);
             } finally {
                 if (client != null) {
                     client.close();
                 }
             }
             return null;
         }

         /**
          * Once the image is downloaded, associates it to the imageView
          */
         @Override
         protected void onPostExecute(Bitmap bitmap) {
             if (isCancelled()) {
                 bitmap = null;
             }

             // Add bitmap to cache
             if (bitmap != null) {
                 synchronized (sHardBitmapCache) {
                     sHardBitmapCache.put(url, bitmap);
                 }
             }

             if (imageViewReference != null) {
                 ImageView imageView = imageViewReference.get();
                 BitmapDownloaderTask bitmapDownloaderTask = getBitmapDownloaderTask(imageView);
                 // Change bitmap only if this process is still associated with it
                 if (this == bitmapDownloaderTask) {
                     imageView.setImageBitmap(bitmap);
                 }
             }
         }

         public void copy(InputStream in, OutputStream out) throws IOException {
             byte[] b = new byte[IO_BUFFER_SIZE];
             int read;
             while ((read = in.read(b)) != -1) {
                 out.write(b, 0, read);
             }
         }
     }

     /**
      * A fake Drawable that will be attached to the imageView while the download is in progress.
      *
      * <p>Contains a reference to the actual download task, so that a download task can be stopped
      * if a new binding is required, and makes sure that only the last started download process can
      * bind its result, independently of the download finish order.</p>
      */
     static class DownloadedDrawable extends ColorDrawable {
         private final WeakReference<BitmapDownloaderTask> bitmapDownloaderTaskReference;

         public DownloadedDrawable(BitmapDownloaderTask bitmapDownloaderTask) {
             super(Color.BLACK);
             bitmapDownloaderTaskReference =
                 new WeakReference<BitmapDownloaderTask>(bitmapDownloaderTask);
         }

         public BitmapDownloaderTask getBitmapDownloaderTask() {
             return bitmapDownloaderTaskReference.get();
         }
     }
 }
	/*
	* Copyright (C) 2010 The Android Open Source Project
	*
	* 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 com.example.android.xmladapters;

	import org.apache.http.HttpEntity;
	import org.apache.http.HttpResponse;
	import org.apache.http.HttpStatus;
	import org.apache.http.client.methods.HttpGet;

	import android.graphics.Bitmap;
	import android.graphics.BitmapFactory;
	import android.graphics.Color;
	import android.graphics.drawable.ColorDrawable;
	import android.graphics.drawable.Drawable;
	import android.net.http.AndroidHttpClient;
	import android.os.AsyncTask;
	import android.os.Handler;
	import android.util.Log;
	import android.widget.ImageView;

	import java.io.BufferedOutputStream;
	import java.io.ByteArrayOutputStream;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.OutputStream;
	import java.lang.ref.SoftReference;
	import java.lang.ref.WeakReference;
	import java.util.HashMap;
	import java.util.LinkedHashMap;
	import java.util.Map;
	import java.util.concurrent.ConcurrentHashMap;

	/**
	* This helper class download images from the Internet and binds those with the provided ImageView.
	*
	* <p>It requires the INTERNET permission, which should be added to your application's manifest
	* file.</p>
	*
	* A local cache of downloaded images is maintained internally to improve performance.
	*/
	public class ImageDownloader {
	private static final String LOG_TAG = "ImageDownloader";

	private static final int HARD_CACHE_CAPACITY = 40;
	private static final int DELAY_BEFORE_PURGE = 30 * 1000; // in milliseconds

	// Hard cache, with a fixed maximum capacity and a life duration
	private final static HashMap<String, Bitmap> sHardBitmapCache =
	new LinkedHashMap<String, Bitmap>(HARD_CACHE_CAPACITY / 2, 0.75f, true) {
	private static final long serialVersionUID = -7190622541619388252L;
	@Override
	protected boolean removeEldestEntry(Map.Entry<String, Bitmap> eldest) {
	if (size() > HARD_CACHE_CAPACITY) {
	// Entries push-out of hard reference cache are transferred to soft reference cache
	sSoftBitmapCache.put(eldest.getKey(), new SoftReference<Bitmap>(eldest.getValue()));
	return true;
	} else {
	return false;
	}
	}
	};

	// Soft cache for bitmap kicked out of hard cache
	private final static ConcurrentHashMap<String, SoftReference<Bitmap>> sSoftBitmapCache =
	new ConcurrentHashMap<String, SoftReference<Bitmap>>(HARD_CACHE_CAPACITY / 2);

	private final Handler purgeHandler = new Handler();

	private final Runnable purger = new Runnable() {
	public void run() {
	clearCache();
	}
	};

	/**
	* Download the specified image from the Internet and binds it to the provided ImageView. The
	* binding is immediate if the image is found in the cache and will be done asynchronously
	* otherwise. A null bitmap will be associated to the ImageView if an error occurs.
	*
	* @param url The URL of the image to download.
	* @param imageView The ImageView to bind the downloaded image to.
	*/
	public void download(String url, ImageView imageView) {
	download(url, imageView, null);
	}

	/**
	* Same as {@link #download(String, ImageView)}, with the possibility to provide an additional
	* cookie that will be used when the image will be retrieved.
	*
	* @param url The URL of the image to download.
	* @param imageView The ImageView to bind the downloaded image to.
	* @param cookie A cookie String that will be used by the http connection.
	*/
	public void download(String url, ImageView imageView, String cookie) {
	resetPurgeTimer();
	Bitmap bitmap = getBitmapFromCache(url);

	if (bitmap == null) {
	forceDownload(url, imageView, cookie);
	} else {
	cancelPotentialDownload(url, imageView);
	imageView.setImageBitmap(bitmap);
	}
	}

	/*
	* Same as download but the image is always downloaded and the cache is not used.
	* Kept private at the moment as its interest is not clear.
	private void forceDownload(String url, ImageView view) {
	forceDownload(url, view, null);
	}
	*/

	/**
	* Same as download but the image is always downloaded and the cache is not used.
	* Kept private at the moment as its interest is not clear.
	*/
	private void forceDownload(String url, ImageView imageView, String cookie) {
	// State sanity: url is guaranteed to never be null in DownloadedDrawable and cache keys.
	if (url == null) {
	imageView.setImageDrawable(null);
	return;
	}

	if (cancelPotentialDownload(url, imageView)) {
	BitmapDownloaderTask task = new BitmapDownloaderTask(imageView);
	DownloadedDrawable downloadedDrawable = new DownloadedDrawable(task);
	imageView.setImageDrawable(downloadedDrawable);
	task.execute(url, cookie);
	}
	}

	/**
	* Clears the image cache used internally to improve performance. Note that for memory
	* efficiency reasons, the cache will automatically be cleared after a certain inactivity delay.
	*/
	public void clearCache() {
	sHardBitmapCache.clear();
	sSoftBitmapCache.clear();
	}

	private void resetPurgeTimer() {
	purgeHandler.removeCallbacks(purger);
	purgeHandler.postDelayed(purger, DELAY_BEFORE_PURGE);
	}

	/**
	* Returns true if the current download has been canceled or if there was no download in
	* progress on this image view.
	* Returns false if the download in progress deals with the same url. The download is not
	* stopped in that case.
	*/
	private static boolean cancelPotentialDownload(String url, ImageView imageView) {
	BitmapDownloaderTask bitmapDownloaderTask = getBitmapDownloaderTask(imageView);

	if (bitmapDownloaderTask != null) {
	String bitmapUrl = bitmapDownloaderTask.url;
	if ((bitmapUrl == null) \|\| (!bitmapUrl.equals(url))) {
	bitmapDownloaderTask.cancel(true);
	} else {
	// The same URL is already being downloaded.
	return false;
	}
	}
	return true;
	}

	/**
	* @param imageView Any imageView
	* @return Retrieve the currently active download task (if any) associated with this imageView.
	* null if there is no such task.
	*/
	private static BitmapDownloaderTask getBitmapDownloaderTask(ImageView imageView) {
	if (imageView != null) {
	Drawable drawable = imageView.getDrawable();
	if (drawable instanceof DownloadedDrawable) {
	DownloadedDrawable downloadedDrawable = (DownloadedDrawable)drawable;
	return downloadedDrawable.getBitmapDownloaderTask();
	}
	}
	return null;
	}

	/**
	* @param url The URL of the image that will be retrieved from the cache.
	* @return The cached bitmap or null if it was not found.
	*/
	private Bitmap getBitmapFromCache(String url) {
	// First try the hard reference cache
	synchronized (sHardBitmapCache) {
	final Bitmap bitmap = sHardBitmapCache.get(url);
	if (bitmap != null) {
	// Bitmap found in hard cache
	// Move element to first position, so that it is removed last
	sHardBitmapCache.remove(url);
	sHardBitmapCache.put(url, bitmap);
	return bitmap;
	}
	}

	// Then try the soft reference cache
	SoftReference<Bitmap> bitmapReference = sSoftBitmapCache.get(url);
	if (bitmapReference != null) {
	final Bitmap bitmap = bitmapReference.get();
	if (bitmap != null) {
	// Bitmap found in soft cache
	return bitmap;
	} else {
	// Soft reference has been Garbage Collected
	sSoftBitmapCache.remove(url);
	}
	}

	return null;
	}

	/**
	* The actual AsyncTask that will asynchronously download the image.
	*/
	class BitmapDownloaderTask extends AsyncTask<String, Void, Bitmap> {
	private static final int IO_BUFFER_SIZE = 4 * 1024;
	private String url;
	private final WeakReference<ImageView> imageViewReference;

	public BitmapDownloaderTask(ImageView imageView) {
	imageViewReference = new WeakReference<ImageView>(imageView);
	}

	/**
	* Actual download method.
	*/
	@Override
	protected Bitmap doInBackground(String... params) {
	final AndroidHttpClient client = AndroidHttpClient.newInstance("Android");
	url = params[0];
	final HttpGet getRequest = new HttpGet(url);
	String cookie = params[1];
	if (cookie != null) {
	getRequest.setHeader("cookie", cookie);
	}

	try {
	HttpResponse response = client.execute(getRequest);
	final int statusCode = response.getStatusLine().getStatusCode();
	if (statusCode != HttpStatus.SC_OK) {
	Log.w("ImageDownloader", "Error " + statusCode +
	" while retrieving bitmap from " + url);
	return null;
	}

	final HttpEntity entity = response.getEntity();
	if (entity != null) {
	InputStream inputStream = null;
	OutputStream outputStream = null;
	try {
	inputStream = entity.getContent();
	final ByteArrayOutputStream dataStream = new ByteArrayOutputStream();
	outputStream = new BufferedOutputStream(dataStream, IO_BUFFER_SIZE);
	copy(inputStream, outputStream);
	outputStream.flush();

	final byte[] data = dataStream.toByteArray();
	final Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);

	// FIXME : Should use BitmapFactory.decodeStream(inputStream) instead.
	//final Bitmap bitmap = BitmapFactory.decodeStream(inputStream);

	return bitmap;

	} finally {
	if (inputStream != null) {
	inputStream.close();
	}
	if (outputStream != null) {
	outputStream.close();
	}
	entity.consumeContent();
	}
	}
	} catch (IOException e) {
	getRequest.abort();
	Log.w(LOG_TAG, "I/O error while retrieving bitmap from " + url, e);
	} catch (IllegalStateException e) {
	getRequest.abort();
	Log.w(LOG_TAG, "Incorrect URL: " + url);
	} catch (Exception e) {
	getRequest.abort();
	Log.w(LOG_TAG, "Error while retrieving bitmap from " + url, e);
	} finally {
	if (client != null) {
	client.close();
	}
	}
	return null;
	}

	/**
	* Once the image is downloaded, associates it to the imageView
	*/
	@Override
	protected void onPostExecute(Bitmap bitmap) {
	if (isCancelled()) {
	bitmap = null;
	}

	// Add bitmap to cache
	if (bitmap != null) {
	synchronized (sHardBitmapCache) {
	sHardBitmapCache.put(url, bitmap);
	}
	}

	if (imageViewReference != null) {
	ImageView imageView = imageViewReference.get();
	BitmapDownloaderTask bitmapDownloaderTask = getBitmapDownloaderTask(imageView);
	// Change bitmap only if this process is still associated with it
	if (this == bitmapDownloaderTask) {
	imageView.setImageBitmap(bitmap);
	}
	}
	}

	public void copy(InputStream in, OutputStream out) throws IOException {
	byte[] b = new byte[IO_BUFFER_SIZE];
	int read;
	while ((read = in.read(b)) != -1) {
	out.write(b, 0, read);
	}
	}
	}

	/**
	* A fake Drawable that will be attached to the imageView while the download is in progress.
	*
	* <p>Contains a reference to the actual download task, so that a download task can be stopped
	* if a new binding is required, and makes sure that only the last started download process can
	* bind its result, independently of the download finish order.</p>
	*/
	static class DownloadedDrawable extends ColorDrawable {
	private final WeakReference<BitmapDownloaderTask> bitmapDownloaderTaskReference;

	public DownloadedDrawable(BitmapDownloaderTask bitmapDownloaderTask) {
	super(Color.BLACK);
	bitmapDownloaderTaskReference =
	new WeakReference<BitmapDownloaderTask>(bitmapDownloaderTask);
	}

	public BitmapDownloaderTask getBitmapDownloaderTask() {
	return bitmapDownloaderTaskReference.get();
	}
	}
	}