1 package com.cn.gordon.exhibition.walk.utils;  2   3 import java.io.InputStream;  4 import java.lang.ref.SoftReference;  5 import java.net.URL;  6 import java.net.URLConnection;  7 import java.util.HashMap;  8 import java.util.concurrent.BlockingQueue;  9 import java.util.concurrent.LinkedBlockingQueue; 10 import java.util.concurrent.RejectedExecutionHandler; 11 import java.util.concurrent.ThreadPoolExecutor; 12 import java.util.concurrent.TimeUnit; 13  14 import android.graphics.drawable.Drawable; 15 import android.os.Handler; 16 import android.os.Looper; 17 /** 18  * 加载图片类 19  * @author jialg 20  * 21  */ 22 public class AsyncImageLoader { 23     private static final String TAG = "AsyncImageLoader"; 24     private ThreadPoolExecutor mPoolExecutor; 25     private HashMap<String, SoftReference<Drawable>> imageCache; 26     private Handler mMainThreadHandler; 27   28     /** 29      * 创建一个异步图片加载器，默认最大5个工作线程，最大等待队列20 30      */ 31     public AsyncImageLoader() { 32         this(5, 20); 33     } 34   35     /** 36      * 创建一个异步图片加载器，当等待下载的图片超过设置的最大等待数量之后，会从等待队列中放弃一个最早加入队列的任务 37      *  38      * @param maxPoolSize 最大工作线程数 39      * @param queueSize 最大等待数 40      */ 41     public AsyncImageLoader(int maxPoolSize, int queueSize) { 42         this(2, maxPoolSize, 3, TimeUnit.SECONDS, new LinkedBlockingQueue<Runnable>(queueSize), 43                 new ThreadPoolExecutor.DiscardOldestPolicy()); 44     } 45   46     /** 47      * 自定义线程池的加载器,请参考:{@link ThreadPoolExecutor} 48      *  49      * @param corePoolSize 50      * @param maximumPoolSize 51      * @param keepAliveTime 52      * @param unit 53      * @param workQueue 54      * @param handler 55      */ 56     public AsyncImageLoader(int corePoolSize, int maximumPoolSize, long keepAliveTime, 57             TimeUnit unit, BlockingQueue<Runnable> workQueue, RejectedExecutionHandler handler) { 58         imageCache = new HashMap<String, SoftReference<Drawable>>(); 59         mPoolExecutor = new ThreadPoolExecutor(corePoolSize, maximumPoolSize, keepAliveTime, unit, 60                 workQueue, handler); 61         mMainThreadHandler = new Handler(Looper.getMainLooper()); 62     } 63   64     /** 65      * 异步加载一张图片 66      *  67      * @param imageUrl 68      * @param imageCallback 69      */ 70     public void loadDrawable(final String imageUrl, final ImageCallback imageCallback) { 71         if (imageCache.containsKey(imageUrl)) { 72             SoftReference<Drawable> softReference = imageCache.get(imageUrl); 73             Drawable drawable = softReference.get(); 74             if (drawable != null) { 75                 imageCallback.onLoaded(drawable); 76                 return; 77             } 78         } 79         LoadImageTask task = new LoadImageTask(imageUrl, this, mMainThreadHandler, imageCallback); 80         mPoolExecutor.execute(task); 81     } 82   83     /** 84      * 停止线程池运行，停止之后，将不能在继续调用 {@link #loadDrawable(String, ImageCallback)} 85      */ 86     public void shutdown() { 87         mPoolExecutor.shutdown(); 88         imageCache.clear(); 89     } 90   91     private void cache(String url, Drawable drawable) { 92         imageCache.put(url, new SoftReference<Drawable>(drawable)); 93     } 94   95     /** 96      * 下载任务 97      *  98      */ 99     private static final class LoadImageTask implements Runnable {100  101         private Handler mHandler;102         private ImageCallback mCallback;103         private AsyncImageLoader mLoader;104         private String mPath;105  106         /**107          * @param imgPath 要下载的图片地址108          * @param loader 图片加载器109          * @param handler 主线程Handler110          * @param imageCallback 图片加载回调111          */112         public LoadImageTask(String imgPath, AsyncImageLoader loader, Handler handler,113                 ImageCallback imageCallback) {114             this.mHandler = handler;115             this.mPath = imgPath;116             this.mLoader = loader;117             this.mCallback = imageCallback;118         }119  120         @Override121         public void run() {122             URL url;123             InputStream is = null;124             try {125                 url = new URL(mPath);126                 URLConnection conn = url.openConnection();127                 conn.connect();128                 is = conn.getInputStream();129                 final Drawable drawable = Drawable.createFromStream(is, "src");130                 mLoader.cache(mPath, drawable);131                 mHandler.post(new Runnable() {132  133                     @Override134                     public void run() {135                         mCallback.onLoaded(drawable);136                     }137                 });138             } catch (final Exception e) {139                 mHandler.post(new Runnable() {140  141                     @Override142                     public void run() {143                         mCallback.onError(e);144                     }145                 });146             }147         }148     }149  150     /**151      * 回调接口,在主线程中运行152      * 153      */154     public static interface ImageCallback {155         /**156          * 加载成功157          * 158          * @param imageDrawable 下载下来的图片159          */160         public void onl oaded(Drawable drawable);161  162         /**163          * 加载失败164          * 165          * @param e 异常166          */167         public void one rror(Exception e);168     }169 }

public class EntryActivity extends Activity {    private AsyncImageLoader asyncImageLoader;    private static String ALBUM_PATH = getSDPath() +         java.io.File.separator +  "exhibition_walk";         public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.walkmain);        asyncImageLoader= new AsyncImageLoader();        init();            }      private void init(){        asyncImageLoader.loadDrawable(urlStr, new ImageCallback(){                     @Override                     public void onl oaded(Drawable imageDrawable) {                         if(imageDrawable != null){                             v1.setImageDrawable(imageDrawable);                             BitmapDrawable draw = (BitmapDrawable) imageDrawable;                             final Bitmap bitmap = draw.getBitmap();                             try {                                   if (bitmap!=null) {                                     Toast.makeText(EntryActivity.this, "下载的图片可用", Toast.LENGTH_SHORT).show();                                     savePicture(bitmap, System.currentTimeMillis()+".jpg");                                      }else{                                                                                Toast.makeText(EntryActivity.this, "下载的图片不可用", Toast.LENGTH_SHORT).show();                                    }                             } catch (IOException e) {                                   e.printStackTrace();                               }                           }                     }                    @Override                    public void one rror(Exception e) {                                            }                });    }    private void savePicture(Bitmap bitmap,String fileName) throws IOException{        File dirFile = new File(ALBUM_PATH);          if(!dirFile.exists()){              dirFile.mkdirs();              Toast.makeText(EntryActivity.this, "创建文件夹", Toast.LENGTH_SHORT).show();        }          File myCaptureFile = new File(ALBUM_PATH +  java.io.File.separator +fileName);          BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(myCaptureFile));          bitmap.compress(Bitmap.CompressFormat.JPEG, 80, bos);          bos.flush();          bos.close();      }/**     * 获取sd卡的路径     *      * @return 路径的字符串     */    public static String getSDPath() {        File sdDir = null;        boolean sdCardExist = Environment.getExternalStorageState().equals(                android.os.Environment.MEDIA_MOUNTED); // 判断sd卡是否存在        if (sdCardExist) {            sdDir = Environment.getExternalStorageDirectory();// 获取外存目录        }        return sdDir.toString();    }}  

1 <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />2     <uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS" />