Android Bitmap Load fetchImage(final Context context, final String url, final OnFetchCompleteListener callback)

Description

Only call this method from the main (UI) thread.

License

Apache License

Declaration

public static void fetchImage(final Context context, final String url,
        final OnFetchCompleteListener callback) 

Method Source Code

/*//from   w ww.  j  av a  2s . c o m
 * Copyright 2011 Google Inc.
 *
 * 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.
 */

import com.google.android.apps.iosched.service.SyncService;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.HttpStatus;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.util.EntityUtils;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.AsyncTask;
import android.os.Environment;
import android.text.TextUtils;
import android.util.Log;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Main{
    private static final String TAG = "BitmapUtils";
    /**
     * Only call this method from the main (UI) thread. The {@link OnFetchCompleteListener} callback
     * be invoked on the UI thread, but image fetching will be done in an {@link AsyncTask}.
     */
    public static void fetchImage(final Context context, final String url,
            final OnFetchCompleteListener callback) {
        fetchImage(context, url, null, null, callback);
    }
    /**
     * Only call this method from the main (UI) thread. The {@link OnFetchCompleteListener} callback
     * be invoked on the UI thread, but image fetching will be done in an {@link AsyncTask}.
     *
     * @param cookie An arbitrary object that will be passed to the callback.
     */
    public static void fetchImage(final Context context, final String url,
            final BitmapFactory.Options decodeOptions, final Object cookie,
            final OnFetchCompleteListener callback) {
        new AsyncTask<String, Void, Bitmap>() {
            @Override
            protected Bitmap doInBackground(String... params) {
                final String url = params[0];
                if (TextUtils.isEmpty(url)) {
                    return null;
                }

                // First compute the cache key and cache file path for this URL
                File cacheFile = null;
                try {
                    MessageDigest mDigest = MessageDigest
                            .getInstance("SHA-1");
                    mDigest.update(url.getBytes());
                    final String cacheKey = bytesToHexString(mDigest
                            .digest());
                    if (Environment.MEDIA_MOUNTED.equals(Environment
                            .getExternalStorageState())) {
                        cacheFile = new File(
                                Environment.getExternalStorageDirectory()
                                        + File.separator + "Android"
                                        + File.separator + "data"
                                        + File.separator
                                        + context.getPackageName()
                                        + File.separator + "cache"
                                        + File.separator + "bitmap_"
                                        + cacheKey + ".tmp");
                    }
                } catch (NoSuchAlgorithmException e) {
                    // Oh well, SHA-1 not available (weird), don't cache bitmaps.
                }

                if (cacheFile != null && cacheFile.exists()) {
                    Bitmap cachedBitmap = BitmapFactory.decodeFile(
                            cacheFile.toString(), decodeOptions);
                    if (cachedBitmap != null) {
                        return cachedBitmap;
                    }
                }

                try {
                    // TODO: check for HTTP caching headers
                    final HttpClient httpClient = SyncService
                            .getHttpClient(context.getApplicationContext());
                    final HttpResponse resp = httpClient
                            .execute(new HttpGet(url));
                    final HttpEntity entity = resp.getEntity();

                    final int statusCode = resp.getStatusLine()
                            .getStatusCode();
                    if (statusCode != HttpStatus.SC_OK || entity == null) {
                        return null;
                    }

                    final byte[] respBytes = EntityUtils
                            .toByteArray(entity);

                    // Write response bytes to cache.
                    if (cacheFile != null) {
                        try {
                            cacheFile.getParentFile().mkdirs();
                            cacheFile.createNewFile();
                            FileOutputStream fos = new FileOutputStream(
                                    cacheFile);
                            fos.write(respBytes);
                            fos.close();
                        } catch (FileNotFoundException e) {
                            Log.w(TAG, "Error writing to bitmap cache: "
                                    + cacheFile.toString(), e);
                        } catch (IOException e) {
                            Log.w(TAG, "Error writing to bitmap cache: "
                                    + cacheFile.toString(), e);
                        }
                    }

                    // Decode the bytes and return the bitmap.
                    return BitmapFactory.decodeByteArray(respBytes, 0,
                            respBytes.length, decodeOptions);
                } catch (Exception e) {
                    Log.w(TAG,
                            "Problem while loading image: " + e.toString(),
                            e);
                }
                return null;
            }

            @Override
            protected void onPostExecute(Bitmap result) {
                callback.onFetchComplete(cookie, result);
            }
        }.execute(url);
    }
    private static String bytesToHexString(byte[] bytes) {
        // http://stackoverflow.com/questions/332079
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < bytes.length; i++) {
            String hex = Integer.toHexString(0xFF & bytes[i]);
            if (hex.length() == 1) {
                sb.append('0');
            }
            sb.append(hex);
        }
        return sb.toString();
    }
}

Related

1. decodeSampledBitmapFromResource(Resources res, int resId, int reqWidth, int reqHeight)
2. decodeSampledBitmapFromUrl(URL url, int reqWidth, int reqHeight)
3. decodeSampledBitmapStreamForSize(InputStream is, int reqWidth, int reqHeight)
4. download(String url, String fileName)
5. fetchImage(final Context context, final String url, final BitmapFactory.Options decodeOptions, final Object cookie, final OnFetchCompleteListener callback)
6. getBitmap(Resources resources, int resourceId)
7. getBitmap(String url, Context context, String newPicName)
8. getBitmapFromAsset(Context context, String strName)
9. getBitmapFromFile(File file)