图片加载的优化 --- 实现图片的缓存、本地内存及网络的三重筛选之后的加载

package com.dusk.lin.biz;import java.io.ByteArrayOutputStream;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.net.HttpURLConnection;import java.net.URL;import android.graphics.Bitmap;import android.graphics.Bitmap.CompressFormat;import android.graphics.BitmapFactory;import android.graphics.BitmapFactory.Options;import android.os.AsyncTask;import android.support.v4.util.LruCache;import android.util.Log;import android.widget.ImageView;import com.dusk.lin.constant.MConstant;/** * @author Dusk * @version 1.0 *  * */public class ImageLoaderBiz {//定义出一个LruCache作为第一重图片数据的加载源：String 图片的网络路径作为key，  bitmap 图片作为值private static LruCache<String, Bitmap> lruCache;static{int cacheSize = 1024*1024*4;lruCache = new LruCache<String, Bitmap>(cacheSize ){@Overrideprotected int sizeOf(String key, Bitmap value) {return value.getByteCount();}};}/** * 该方法向外部直接返回指定网络路径的图片 * */public static Bitmap getImage(String imageUrl){Bitmap bitmap;if(imageUrl == null){Log.d("TAG:getimage", "imageUrl为空");return null;}//先判断LruCache中是否存在指定图片：存在返回该图片，不存在，向下刷选本地内存if((bitmap = getImageFromLruCache(imageUrl)) != null){return bitmap;}//判断手机内存中的Cache文件夹下是否缓存过指定图片：有，则返回该图片；没有，向下执行异步的网络图片下载if((bitmap = getImageFromCacheFile(imageUrl)) != null ){return bitmap;}//异步加载网络图片asyncGetImageByHttpURLConnection(imageUrl);return b;}/** * 该方法可以直接设定指定imageview的src图片 *  * */public static void setImage(String imageUrl, ImageView imageAvatar){Bitmap bitmap;if(imageUrl == null){Log.d("TAG:getimage", "imageUrl为空");return;}if((bitmap = getImageFromLruCache(imageUrl)) != null){imageAvatar.setImageBitmap(bitmap);return ;}if((bitmap = getImageFromCacheFile(imageUrl)) != null ){imageAvatar.setImageBitmap(bitmap);return ;}asyncGetImageByHttpURLConnection(imageUrl, imageAvatar);}    private static void asyncGetImageByHttpURLConnection(String imageUrl,final ImageView imageAvatar) {new MyImageLoadAsyncTask(new ImageLoadAsyncListener() {@Overridepublic void onImageLoadEnd(Bitmap bitmap) {imageAvatar.setImageBitmap(bitmap);}}).execute(imageUrl);}private static  Bitmap b = null;private static void asyncGetImageByHttpURLConnection(final String imageUrl) {new MyImageLoadAsyncTask(new ImageLoadAsyncListener() {@Overridepublic void onImageLoadEnd(Bitmap bitmap) {b = bitmap;}}).execute(imageUrl);}protected static void saveImageToCacheFile(Bitmap b2, String path) {//拿到手机内存中的cache目录File fileCache = MConstant.context.getCacheDir();if(!fileCache.exists()){fileCache.mkdirs();}//文件名酌情而定String fileName = path.substring(path.indexOf("/")+1);File file = new File(fileCache, fileName);try {OutputStream out = new FileOutputStream(file);b2.compress(CompressFormat.JPEG, 100, out);} catch (FileNotFoundException e) {e.printStackTrace();}}private static class MyImageLoadAsyncTask extends AsyncTask<String, Void, Bitmap>{        private ImageLoadAsyncListener listener;        public MyImageLoadAsyncTask(ImageLoadAsyncListener listener) {    this.listener = listener;        }@Overrideprotected Bitmap doInBackground(String... params) {// TODO Auto-generated method stubBitmap bitmap = null;String imageUrl = params[0];String path = MConstant.ROOT + imageUrl;URL url = null;InputStream in = null;HttpURLConnection conn = null;try {url= new URL(path);conn = (HttpURLConnection) url.openConnection();conn.setReadTimeout(5000);conn.setRequestMethod("GET");conn.setDoInput(true);conn.connect();int status = conn.getResponseCode();if(status == 200){in = conn.getInputStream();if(in != null){//先压缩图片bitmap = compressImage(in);//再分别在缓存和内存中备份lruCache.put(imageUrl, bitmap);saveImageToCacheFile(bitmap, imageUrl);}else{Log.e("TAG:imageloadByAsync", "数据库响应数据流为空");}}else{Log.e("TAG:imageloadByAsync", "数据库响应异常:"+status);}} catch (IOException e) {e.printStackTrace();}finally{conn.disconnect();if(in != null){in = null;}}return bitmap;}@Overrideprotected void onPostExecute(Bitmap result) {super.onPostExecute(result);listener.onImageLoadEnd(result);}}public interface ImageLoadAsyncListener{public void onImageLoadEnd(Bitmap bitmap);}private static Bitmap getImageFromCacheFile(String imageUrl) {String fileName = imageUrl.substring(imageUrl.lastIndexOf("/")+1);Bitmap bitmap = null;File cacheFile = MConstant.context.getCacheDir();if(cacheFile != null){File[] files = cacheFile.listFiles();for(File f : files){if(f.isFile() && f.getName().equals(fileName)){bitmap  = BitmapFactory.decodeFile(f.getAbsolutePath());}}}else{Log.e("TAG:getImageFromCacheFile", "cacheFile=null");}return bitmap;}public static Bitmap compressImage(InputStream in) {ByteArrayOutputStream baos = new ByteArrayOutputStream();int len = 0;byte[] buffer = new byte[1024];try {while((len = in.read(buffer)) != -1){baos.write(buffer, 0, len);}} catch (IOException e) {e.printStackTrace();}byte[] data = baos.toByteArray();Options opts = new Options();opts.inJustDecodeBounds = true;BitmapFactory.decodeByteArray(data, 0, data.length, opts );int width = opts.outWidth;int height = opts.outHeight;int wCompress = 60;int hCompress = 60;int wScale = width/wCompress;int hScale = height/hCompress;int scale = Math.max(wScale, hScale);if(scale <= 0){scale = 1;}opts.inJustDecodeBounds = false;opts.inSampleSize = scale;return BitmapFactory.decodeByteArray(data, 0, data.length, opts);}private static Bitmap getImageFromLruCache(String imageUrl) {return  lruCache.get(imageUrl);}}