Android网络图片缓存（网络cache和本地）

package com.test.imageviewloader; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FilterInputStream; import java.io.IOException; import java.io.InputStream; import java.lang.ref.WeakReference; 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 android.content.Context; 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.util.Log; import android.widget.ImageView; /** * * @author litingchang * */ public class ImageDownloader { private static final String LOG_TAG = ImageDownloader.class.getSimpleName(); // private ImageCache imageCache; ImageCache imageCache; FileCache fileCache; public ImageDownloader(Context context) { imageCache = new ImageCache(); fileCache = new FileCache(context); } /** * 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) { imageCache.resetPurgeTimer(); Bitmap bitmap = imageCache.getBitmapFromCache(url); if(bitmap == null) { forceDownload(url, imageView); } 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 imageView) { if (url == null) { imageView.setImageDrawable(null); //TODO 更改为默认图片 return; } if(cancelPotentialDownload(url, imageView)) { BitmapDownloaderTask task = new BitmapDownloaderTask(imageView); task = new BitmapDownloaderTask(imageView); DownloadedDrawable downloadedDrawable = new DownloadedDrawable(task); imageView.setImageDrawable(downloadedDrawable); task.execute(url); } } /** * @param url * @param imageView * @return */ 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 url * @return */ private Bitmap downloadBitmap(String url) { //try to get image from file cache File file = fileCache.getFromFileCache(url); Bitmap bitmap = null; try { bitmap = BitmapFactory.decodeStream(new FlushedInputStream(new FileInputStream(file))); } catch (FileNotFoundException e1) { bitmap = null; } if(bitmap != null) { return bitmap; } //end of try final HttpClient httpClient = AndroidHttpClient.newInstance("image_downloader"); // final HttpClient httpClient = new DefaultHttpClient(); final HttpGet getRequest = new HttpGet(url); try { HttpResponse httpResponse = httpClient.execute(getRequest); final int statusCode = httpResponse.getStatusLine().getStatusCode(); if(statusCode != HttpStatus.SC_OK) { Log.w(LOG_TAG, "Error " + statusCode + " while retrieving bitmap from " + url); return null; } final HttpEntity httpEntity = httpResponse.getEntity(); if(httpEntity != null) { InputStream inputStream = null; try { inputStream = httpEntity.getContent(); //save file to file cache fileCache.addToFileCache(url, inputStream); //end of save //TODO return BitmapFactory.decodeStream(new FlushedInputStream(new FlushedInputStream(new FileInputStream(file)))); } catch (Exception e) { e.printStackTrace(); }finally { if(inputStream != null) { inputStream.close(); } httpEntity.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 ((httpClient instanceof AndroidHttpClient)) { ((AndroidHttpClient) httpClient).close(); } } return null; } // end of downloadBitmap /* * An InputStream that skips the exact number of bytes provided, unless it reaches EOF. */ 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 b = read(); if (b < 0) { break; // we reached EOF } else { bytesSkipped = 1; // we read one byte } } totalBytesSkipped += bytesSkipped; } return totalBytesSkipped; } } // end of FlushedInputStream /** * @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; } class BitmapDownloaderTask extends AsyncTask<String, Void, Bitmap> { private String url; private WeakReference<ImageView> imageViewWeakReference; public BitmapDownloaderTask(ImageView imageView) { imageViewWeakReference = new WeakReference<ImageView>(imageView); } @Override protected Bitmap doInBackground(String... params) { url = params[0]; return downloadBitmap(url); } @Override protected void onPostExecute(Bitmap bitmap) { if(isCancelled()) { bitmap = null; } //add bitmap to cache imageCache.addBitmapToCache(url, bitmap); if(imageViewWeakReference != null) { ImageView imageView = imageViewWeakReference.get(); BitmapDownloaderTask bitmapDownloaderTask = getBitmapDownloaderTask(imageView); if(this == bitmapDownloaderTask) { imageView.setImageBitmap(bitmap); } } } } // end of BitmapDownloaderTask /** * 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 mak