Java tutorial
/* 50AH-code ========= 50 Android Hacks (http://manning.com/sessa/) book source code Copyright (c) 2012 Manning Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ /* * Copyright (C) 2012 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.manning.androidhacks.hack040.util; import java.io.BufferedInputStream; import java.io.BufferedOutputStream; import java.io.File; import java.io.FileOutputStream; import java.io.IOException; import java.io.InputStream; import java.net.HttpURLConnection; import java.net.URL; import android.app.Activity; import android.content.Context; import android.graphics.Bitmap; import android.net.ConnectivityManager; import android.net.NetworkInfo; import android.util.Log; import android.widget.Toast; import com.manning.androidhacks.hack040.BuildConfig; /** * A simple subclass of {@link ImageResizer} that fetches and resizes images * fetched from a URL. */ public class ImageFetcher extends ImageResizer { private static final String TAG = "ImageFetcher"; /** * Initialize providing a target image width and height for the processing * images. * * @param activity * @param imageWidth * @param imageHeight */ public ImageFetcher(Activity activity, int imageWidth, int imageHeight) { super(activity, imageWidth, imageHeight); init(activity); } /** * Initialize providing a single target image size (used for both width and * height); * * @param activity * @param imageSize */ public ImageFetcher(Activity activity, int imageSize) { super(activity, imageSize); init(activity); } private void init(Context context) { checkConnection(context); } /** * Simple network connection check. * * @param context */ private void checkConnection(Context context) { final ConnectivityManager cm = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); final NetworkInfo networkInfo = cm.getActiveNetworkInfo(); if (networkInfo == null || !networkInfo.isConnectedOrConnecting()) { Toast.makeText(context, "No network connection found.", Toast.LENGTH_LONG).show(); Log.e(TAG, "checkConnection - no connection found"); } } /** * The main process method, which will be called by the ImageWorker in the * AsyncTask background thread. * * @param data * The data to load the bitmap, in this case, a regular http URL * @return The downloaded and resized bitmap */ private Bitmap processBitmap(String data) { if (BuildConfig.DEBUG) { Log.d(TAG, "processBitmap - " + data); } // Download a bitmap, write it to a file final File f = downloadBitmap(mActivity, data, mImageCache.getDiskCache()); if (f != null) { // Return a sampled down version return decodeSampledBitmapFromFile(f.toString(), mImageWidth, mImageHeight); } return null; } @Override protected Bitmap processBitmap(Object data) { return processBitmap(String.valueOf(data)); } /** * Download a bitmap from a URL, write it to a disk and return the File * pointer. This implementation uses a simple disk cache. * * @param context * The context to use * @param urlString * The URL to fetch * @param cache * The disk cache instance to get the download directory from. * @return A File pointing to the fetched bitmap */ public static File downloadBitmap(Context context, String urlString, DiskLruCache cache) { final File cacheFile = new File(cache.createFilePath(urlString)); if (cache.containsKey(urlString)) { if (BuildConfig.DEBUG) { Log.d(TAG, "downloadBitmap - found in http cache - " + urlString); } return cacheFile; } if (BuildConfig.DEBUG) { Log.d(TAG, "downloadBitmap - downloading - " + urlString); } Utils.disableConnectionReuseIfNecessary(); HttpURLConnection urlConnection = null; BufferedOutputStream out = null; try { final URL url = new URL(urlString); urlConnection = (HttpURLConnection) url.openConnection(); final InputStream in = new BufferedInputStream(urlConnection.getInputStream(), Utils.IO_BUFFER_SIZE); out = new BufferedOutputStream(new FileOutputStream(cacheFile), Utils.IO_BUFFER_SIZE); int b; while ((b = in.read()) != -1) { out.write(b); } cache.putFromFetcher(urlString); return cacheFile; } catch (final IOException e) { Log.e(TAG, "Error in downloadBitmap - " + e); } finally { if (urlConnection != null) { urlConnection.disconnect(); } if (out != null) { try { out.close(); } catch (final IOException e) { Log.e(TAG, "Error in downloadBitmap - " + e); } } } return null; } }