Android项目之ImageLoader

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ImageLoader为项目内统管图片资源的类。
项目中的图片分为：缓存图片、磁盘图片、网络图片三类；加载图片的顺序应该为：
先加载内存缓存图片，有则显示，无则加载磁盘缓存图片；磁盘缓存有则显示，无则另启线程下载；下载成功后显示，如果设置了保存则保存至内存和磁盘。
public class ImageLoadTask {    private ImageLoadOptions imageLoadOptions;    private ImageLoadListener imageLoadListener;    /** 内存缓存 */    private BitmapMemoryCache bitmapMemoryCache;    /** 磁盘缓存 */    private DiskCacheImageLoader diskCacheManager;    /** 磁盘图片加载器 */    private DiskImageLoader diskBitmapLoader;    /** 图片下载器 */    private ImageDownloader imageDownloader;    /**     * 当前的加载状态     */    private LoadState loadState = LoadState.未开始;    private DiskImageLoader.LoadTask loadTask;    private ImageDownloader.ImageDownLoadTask imageDownLoadTask;    public ImageLoadTask(ImageLoadOptions imageLoadOptions, ImageLoadListener imageLoadListener,                         BitmapMemoryCache bitmapMemoryCache, DiskCacheImageLoader diskCacheManager,                         DiskImageLoader diskBitmapLoader, ImageDownloader imageDownloader) {        this.imageLoadOptions = imageLoadOptions;        this.imageLoadListener = imageLoadListener;        this.bitmapMemoryCache = bitmapMemoryCache;        this.diskCacheManager = diskCacheManager;        this.diskBitmapLoader = diskBitmapLoader;        this.imageDownloader = imageDownloader;        loadState = LoadState.未开始;    }    /**     * 开始加载     */    void start() {        if (loadState != LoadState.未开始) {            throw new IllegalStateException("该方法只能调用一次");        }        if (imageLoadOptions.isMemoryCacheEnable()) {            Bitmap memoryBitmap = bitmapMemoryCache.get(imageLoadOptions.getKey());            if (memoryBitmap != null) {                imageLoadListener.onLoadSuccessful(ImageLoadListener.BitmapSource.MEMORY_CACHE, memoryBitmap);                loadState = LoadState.加载完成;                return;            }        }        if (imageLoadOptions.isDiskCacheEnable()) {            loadState = LoadState.加载磁盘缓存中;            diskCacheManager.getCache(imageLoadOptions.getKey(), new DiskCacheImageLoader.OnGetDiskCacheListener() {                @Override                public void onGetDiskCache(String key, Bitmap bitmap) {                    if (loadState == LoadState.加载取消) {                        return;                    }                    if (bitmap != null) {                        if (imageLoadOptions.isMemoryCacheEnable()) {                            bitmapMemoryCache.put(imageLoadOptions.getKey(), bitmap);                        }                        imageLoadListener.onLoadSuccessful(ImageLoadListener.BitmapSource.DISK_CACHE, bitmap);                        loadState = LoadState.加载完成;                    } else {                        loadSource();                    }                }            });        } else {            loadSource();        }    }    private void loadSource() {        if (imageLoadOptions.hasUrl() && imageDownloader.isDownloading(imageLoadOptions.getFilePath())) {            loadBitmapFromNet();        } else {            loadBitmapFromDisk(false);        }    }    private void loadBitmapFromDisk(final boolean ifFromNet) {        loadState = LoadState.加载磁盘中;        loadTask = diskBitmapLoader.loadBitmap(imageLoadOptions, new DiskImageLoader.OnLoadResultListener() {            @Override            public void onLoadResult(int result, Bitmap bitmap) {                if (loadState == LoadState.加载取消)                    return;                loadTask = null;                if (result == RESULT_LOAD_SUCCESSFUL) {                    String key = imageLoadOptions.getKey();                    if (imageLoadOptions.isDiskCacheEnable()) {                        diskCacheManager.putCache(key, bitmap);                    }                    if (imageLoadOptions.isMemoryCacheEnable()) {                        bitmapMemoryCache.put(key, bitmap);                    }                    if (ifFromNet)                        imageLoadListener.onLoadSuccessful(ImageLoadListener.BitmapSource.NETWORK, bitmap);                    else                        imageLoadListener.onLoadSuccessful(ImageLoadListener.BitmapSource.FILE, bitmap);                    loadState = LoadState.加载完成;                } else if (result == RESULT_FILE_NOT_EXISTS && imageLoadOptions.hasUrl()                        && !ifFromNet) {                    // 加载网络图片                    loadBitmapFromNet();                } else {                    imageLoadListener.onLoadFailed("本地图片文件加载失败！");                    loadState = LoadState.加载失败;                }            }        });    }    private void loadBitmapFromNet() {        loadState = LoadState.加载网络中;        // 开始网络加载        ImageDownloadListener imageDownloadListener = new ImageDownloadListener() {            @Override            public void onProgressChange(String filePath, int totalSize, int currentSize) {                if (loadState == LoadState.加载取消)                    return;                imageLoadListener.onLoadProgressChange(totalSize, currentSize);            }            @Override            public void onDownloadFinish(String filePath, DownloadResult downloadResult) {                if (loadState == LoadState.加载取消)                    return;                imageDownLoadTask = null;                if (downloadResult == DownloadResult.SUCCESSFUL || downloadResult == DownloadResult.FILE_EXISTS) {                    loadBitmapFromDisk(true);                } else {                    imageLoadListener.onLoadFailed("网络图片加载失败");                    loadState = LoadState.加载失败;                }            }        };        String filePath = imageLoadOptions.getFilePath();        String url = imageLoadOptions.getUrl();        imageDownLoadTask = imageDownloader.download(filePath, url, imageDownloadListener);        imageLoadListener.onStartDownload(); // 通知， 开始下载了    }    public void cancle() {        if (loadState != LoadState.加载取消 && loadState != LoadState.加载完成 && loadState != LoadState.加载失败) {            if (loadState == LoadState.加载磁盘中) {                loadTask.cancel();                loadTask = null;            } else if (loadState == LoadState.加载网络中) {                imageDownLoadTask.cancel();                imageDownLoadTask = null;            }            loadState = LoadState.加载取消;        }    }    /**     * 获取加载状态     */    public LoadState getLoadState() {        return loadState;    }    /** 当前状态 汉字枚举，我喜欢。。。。 */    public enum LoadState {        加载完成, 加载磁盘缓存中, 加载磁盘中, 加载网络中, 未开始, 加载取消, 加载失败;    }}
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