ImageFetcher.java

/*
 * 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.quark.image;

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.content.Context;
import android.graphics.Bitmap;
import android.net.ConnectivityManager;
import android.net.NetworkInfo;

/**
 * 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";

	private static final int HTTP_CACHE_SIZE = 10 * 1024 * 1024; // 10MB

	public static final String HTTP_CACHE_DIR = "http";

	/**
	 * Initialize providing a target image width and height for the processing
	 * images.
	 * 
	 * @param context
	 * @param imageWidth
	 * @param imageHeight
	 */
	public ImageFetcher(Context context, int imageWidth, int imageHeight) {
		super(context, imageWidth, imageHeight);
		init(context);
	}

	/**
	 * Initialize providing a single target image size (used for both width and
	 * height);
	 * 
	 * @param context
	 * @param imageSize
	 */
	public ImageFetcher(Context context, int imageSize) {
		super(context, imageSize);
		init(context);
	}

	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()) {
		}
	}

	/**
	 * 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) {

		// Download a bitmap, write it to a file
		final File f = downloadBitmap(mContext, data);

		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
	 * @return A File pointing to the fetched bitmap
	 */
	public static File downloadBitmap(Context context, String urlString) {
		final File cacheDir = DiskLruCache.getDiskCacheDir(context,
				HTTP_CACHE_DIR);

		final DiskLruCache cache = DiskLruCache.openCache(context, cacheDir,
				HTTP_CACHE_SIZE);

		final File cacheFile = new File(cache.createFilePath(urlString));

		if (cache.containsKey(urlString)) {
			return cacheFile;
		}


		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);
			}

			return cacheFile;

		} catch (final IOException e) {
		} finally {
			if (urlConnection != null) {
				urlConnection.disconnect();
			}
			if (out != null) {
				try {
					out.close();
				} catch (final IOException e) {
				}
			}
		}

		return null;
	}
}