实现异步加载本地图片，防止oom错误

package com.su.doubanrise.widget;import java.io.File;import java.lang.ref.SoftReference;import java.util.Collections;import java.util.HashMap;import java.util.Map;import java.util.WeakHashMap;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Handler;import android.os.Message;import android.widget.ImageView;import com.su.doubanrise.DoubanApp;import com.su.doubanrise.R;import com.su.doubanrise.overall.Constant;import com.su.doubanrise.util.FileDownLoader;import com.su.doubanrise.util.Str;public class AsyncImageLoader {//TODO Remove the callback ,set imageView in function.//TODO Add Thread Pool Reference:OscChina BitmapManager//TODO Adapter convertview reuse private Context mcontext;private HashMap<String, SoftReference<Bitmap>> imageCache = new HashMap<String, SoftReference<Bitmap>>();private static Map<ImageView, String> imageViews;private Bitmap defbitmap;;public AsyncImageLoader() {this.mcontext = DoubanApp.getContext();defbitmap = BitmapFactory.decodeResource(mcontext.getResources(),R.drawable.ic_launcher);imageViews = Collections.synchronizedMap(new WeakHashMap<ImageView, String>());}/** * 异步加载sd卡的图片 ， *  * @param uri * @param imageView * @param imageCallback * @return */private Bitmap loadBitmapFromSD(final String uri,final ImageView imageView, final ImageCallback imageCallback) {if (imageCache.containsKey(uri)) {SoftReference<Bitmap> SoftReference = imageCache.get(uri);Bitmap bitmap = SoftReference.get();if (bitmap != null) {return bitmap;}}final Handler handler = new Handler() {public void handleMessage(Message msg) {imageCallback.imageLoaded((Bitmap) msg.obj, imageView, uri);}};new Thread() {public void run() {Bitmap bitmap = null;bitmap = getBitmapFromFile(uri);imageCache.put(uri, new SoftReference<Bitmap>(bitmap));if (!new File(uri).isFile()) {bitmap = BitmapFactory.decodeResource(mcontext.getResources(), R.drawable.ic_launcher);}Message msg = handler.obtainMessage(0, bitmap);handler.sendMessage(msg);bitmap = null;}}.start();return defbitmap;}/** * 异步加载Net上的图片 ， *  * @param url * @param imageView * @param imageCallback * @return */private Bitmap loadBitmapFromNet(final String url,final ImageView imageView, final int opsize,final ImageCallback imageCallback) {imageViews.put(imageView, url);final String savePath = Constant.PICPATH + Str.md5(url);if (imageCache.containsKey(url)) {Bitmap bitmap = imageCache.get(url).get();if (bitmap != null) {return bitmap;}}final Handler handler = new Handler() {public void handleMessage(Message msg) {String tag = imageViews.get(imageView);if (tag != null && tag.equals(url)) {imageCallback.imageLoaded((Bitmap) msg.obj, imageView, url);}}};new Thread() {public void run() {try {FileDownLoader.downloadImg(url, savePath);} catch (Exception e) {e.printStackTrace();}Bitmap bitmap = null;bitmap = getBitmapFromFile(savePath, opsize);imageCache.put(url, new SoftReference<Bitmap>(bitmap));if (bitmap != null) {Message msg = handler.obtainMessage(0, bitmap);handler.sendMessage(msg);}}}.start();return defbitmap;}private interface ImageCallback {public void imageLoaded(Bitmap imageBitmap, ImageView imageView,String uri);}/** * 从本读读取图片 *  * @param uri * @return */private Bitmap getBitmapFromFile(String uri) {BitmapFactory.Options options = new BitmapFactory.Options();options.inSampleSize = 8;Bitmap bitmap = BitmapFactory.decodeFile(uri, options);return bitmap;}/** * 从本读读取图片 添加opt参数 *  * @param uri * @return */private Bitmap getBitmapFromFile(String uri, int opsize) {BitmapFactory.Options options = new BitmapFactory.Options();options.inSampleSize = opsize;options.inPurgeable = true;Bitmap bitmap = BitmapFactory.decodeFile(uri, options);// 这里还是会出现oom??return bitmap;}/** * 最终暴露给用户的接口 *  * @param url * @param imageView */public void setAsyncBitmapFromNet(String url, ImageView imageView) {if (url == null) {return;}imageView.setImageBitmap(loadBitmapFromNet(url, imageView, 1,new ImageCallback() {public void imageLoaded(Bitmap imageBitmap,ImageView imageView, String imageUrl) {imageView.setImageBitmap(imageBitmap);}}));}/** * 异步加载本地图片 *  * @param uri * @param imageView */public void setAsyncBitmapFromSD(String uri, ImageView imageView) {if (uri == null) {return;}imageView.setImageBitmap(loadBitmapFromSD(uri, imageView,new ImageCallback() {public void imageLoaded(Bitmap imageBitmap,ImageView imageView, String imageUrl) {imageView.setImageBitmap(imageBitmap);}}));}/** * 由于加载本地图片时间较短 ，其实可以使用这个方法减小线程的开销 *  * @param uri * @param imageView */public void setBitmapFromSD(String uri, ImageView imageView) {if (uri == null) {return;}imageView.setImageBitmap(getBitmapFromFile(uri));}}