异步线程加载图片工具类

/**

 * 异步线程加载图片工具类

 * 使用说明：

 * BitmapManager bmpManager;

 * bmpManager = new BitmapManager(BitmapFactory.decodeResource(context.getResources(), R.drawable.loading));

 * bmpManager.loadBitmap(imageURL, imageView);

 */

public class BitmapManager {  

      

    private static HashMap<String, SoftReference<Bitmap>> cache;  

    private static ExecutorService pool;  

    private static Map<ImageView, String> imageViews;  

    private Bitmap defaultBmp;  

    

    static {  

        cache = new HashMap<String, SoftReference<Bitmap>>();  

        pool = Executors.newFixedThreadPool(5);  //固定线程池

        imageViews = Collections.synchronizedMap(new WeakHashMap<ImageView, String>());

    }  

    

    public BitmapManager(){}

    

    public BitmapManager(Bitmap def) {

        this.defaultBmp = def;

    }

    

    /**

     * 设置默认图片

     * @param bmp

     */

    public void setDefaultBmp(Bitmap bmp) {  

        defaultBmp = bmp;  

    }   

  

    /**

     * 加载图片

     * @param url

     * @param imageView

     */

    public void loadBitmap(String url, ImageView imageView) {  

        loadBitmap(url, imageView, this.defaultBmp, 0, 0);

    }

    

    /**

     * 加载图片-可设置加载失败后显示的默认图片

     * @param url

     * @param imageView

     * @param defaultBmp

     */

    public void loadBitmap(String url, ImageView imageView, Bitmap defaultBmp) {  

        loadBitmap(url, imageView, defaultBmp, 0, 0);

    }

    

    /**

     * 加载图片-可指定显示图片的高宽

     * @param url

     * @param imageView

     * @param width

     * @param height

     */

    public void loadBitmap(String url, ImageView imageView, Bitmap defaultBmp, int width, int height) {  

        imageViews.put(imageView, url);  

        Bitmap bitmap = getBitmapFromCache(url);  

   

        if (bitmap != null) {  

            //显示缓存图片

            imageView.setImageBitmap(bitmap);  

        } else {  

            //加载SD卡中的图片缓存

            String filename = FileUtils.getFileName(url);

            String filepath = imageView.getContext().getFilesDir() + File.separator + filename;

            File file = new File(filepath);

            if(file.exists()){

                //显示SD卡中的图片缓存

                Bitmap bmp = ImageUtils.getBitmap(imageView.getContext(), filename);

                imageView.setImageBitmap(bmp);

            }else{

                //线程加载网络图片

                imageView.setImageBitmap(defaultBmp);

                queueJob(url, imageView, width, height);

            }

        }  

    }  

  

    /**

     * 从缓存中获取图片

     * @param url

     */

    public Bitmap getBitmapFromCache(String url) {  

        Bitmap bitmap = null;

        if (cache.containsKey(url)) {  

            bitmap = cache.get(url).get();  

        }  

        return bitmap;  

    }  

    

    /**

     * 从网络中加载图片

     * @param url

     * @param imageView

     * @param width

     * @param height

     */

    public void queueJob(final String url, final ImageView imageView, final int width, final int height) {  

        /* Create handler in UI thread. */  

        final Handler handler = new Handler() {  

            public void handleMessage(Message msg) {  

                String tag = imageViews.get(imageView);  

                if (tag != null && tag.equals(url)) {  

                    if (msg.obj != null) {  

                        imageView.setImageBitmap((Bitmap) msg.obj);  

                        try {

                            //向SD卡中写入图片缓存

                            ImageUtils.saveImage(imageView.getContext(), FileUtils.getFileName(url), (Bitmap) msg.obj);

                        } catch (IOException e) {

                            e.printStackTrace();

                        }

                    } 

                }  

            }  

        };  

  

        pool.execute(new Runnable() {   

            public void run() {  

                Message message = Message.obtain();  

                message.obj = downloadBitmap(url, width, height);  

                handler.sendMessage(message);  

            }  

        });  

    } 

  

    /**

     * 下载图片-可指定显示图片的高宽

     * @param url

     * @param width

     * @param height

     */

    private Bitmap downloadBitmap(String url, int width, int height) {   

        Bitmap bitmap = null;

        try {

            //http加载图片

            bitmap = ApiClient.getNetBitmap(url);

            if(width > 0 && height > 0) {

                //指定显示图片的高宽

                bitmap = Bitmap.createScaledBitmap(bitmap, width, height, true);

            } 

            //放入缓存

            cache.put(url, new SoftReference<Bitmap>(bitmap));

        } catch (AppException e) {

            e.printStackTrace();

        }

        return bitmap;  

    }  

}