Android Universal Image Loader 流程分析(1)

只是分析流程

public void displayImage(String uri, ImageView imageView, DisplayImageOptions options, ImageLoadingListener listener) {
        checkConfiguration();
        if (imageView == null) {
            throw new IllegalArgumentException(ERROR_WRONG_ARGUMENTS);
        }
        if (listener == null) {
            listener = emptyListener;
        }
        if (options == null) {
            options = configuration.defaultDisplayImageOptions;
        }

        if (TextUtils.isEmpty(uri)) {
            engine.cancelDisplayTaskFor(imageView);
            listener.onLoadingStarted(uri, imageView);
            if (options.shouldShowImageForEmptyUri()) {
                imageView.setImageResource(options.getImageForEmptyUri());
            } else {
                imageView.setImageBitmap(null);
            }
            listener.onLoadingComplete(uri, imageView, null);
            return;
        }

        ImageSize targetSize = ImageSizeUtils.defineTargetSizeForView(imageView, configuration.maxImageWidthForMemoryCache,
                configuration.maxImageHeightForMemoryCache);
        String memoryCacheKey = MemoryCacheUtil.generateKey(uri, targetSize);
        engine.prepareDisplayTaskFor(imageView, memoryCacheKey);

        listener.onLoadingStarted(uri, imageView);
        Bitmap bmp = configuration.memoryCache.get(memoryCacheKey);
        if (bmp != null && !bmp.isRecycled()) {
            if (configuration.loggingEnabled) L.i(LOG_LOAD_IMAGE_FROM_MEMORY_CACHE, memoryCacheKey);

            if (options.shouldPostProcess()) {
                ImageLoadingInfo imageLoadingInfo = new ImageLoadingInfo(uri, imageView, targetSize, memoryCacheKey, options, listener,
                        engine.getLockForUri(uri));
                ProcessAndDisplayImageTask displayTask = new ProcessAndDisplayImageTask(engine, bmp, imageLoadingInfo, options.getHandler());
                engine.submit(displayTask);
            } else {
                options.getDisplayer().display(bmp, imageView);
                listener.onLoadingComplete(uri, imageView, bmp);
            }
        } else {
            if (options.shouldShowStubImage()) {
                imageView.setImageResource(options.getStubImage());
            } else {
                if (options.isResetViewBeforeLoading()) {
                    imageView.setImageBitmap(null);
                }
            }

            ImageLoadingInfo imageLoadingInfo = new ImageLoadingInfo(uri, imageView, targetSize, memoryCacheKey, options, listener, engine.getLockForUri(uri));
            LoadAndDisplayImageTask displayTask = new LoadAndDisplayImageTask(engine, imageLoadingInfo, options.getHandler());
            engine.submit(displayTask);
        }
    }

1.检查内存中是否存在

2.如果存在 执行ProcessAndDisplayImageTask  得到bitmap  处理bitmap 显示

3.不存在 则 执行LoadAndDisplayImageTask 

。。。。。LoadAndDisplayImageTask。。
。。
@Override
	public void run() {
		if (waitIfPaused()) return;
		if (delayIfNeed()) return;

		ReentrantLock loadFromUriLock = imageLoadingInfo.loadFromUriLock;
		log(LOG_START_DISPLAY_IMAGE_TASK);
		if (loadFromUriLock.isLocked()) {
			log(LOG_WAITING_FOR_IMAGE_LOADED);
		}

		loadFromUriLock.lock();
		Bitmap bmp;
		try {
			if (checkTaskIsNotActual()) return;

			bmp = configuration.memoryCache.get(memoryCacheKey);
			if (bmp == null) {
				bmp = tryLoadBitmap();
				if (bmp == null) return;

				if (checkTaskIsNotActual() || checkTaskIsInterrupted()) return;

				if (options.shouldPreProcess()) {
					log(LOG_PREPROCESS_IMAGE);
					bmp = options.getPreProcessor().process(bmp);
					if (bmp == null) {
						L.w(WARNING_PRE_PROCESSOR_NULL);
					}
				}

				if (bmp != null && options.isCacheInMemory()) {
					log(LOG_CACHE_IMAGE_IN_MEMORY);
					configuration.memoryCache.put(memoryCacheKey, bmp);
				}
			} else {
				log(LOG_GET_IMAGE_FROM_MEMORY_CACHE_AFTER_WAITING);
			}

			if (bmp != null && options.shouldPostProcess()) {
				log(LOG_POSTPROCESS_IMAGE);
				bmp = options.getPostProcessor().process(bmp);
				if (bmp == null) {
					L.w(WARNING_POST_PROCESSOR_NULL, memoryCacheKey);
				}
			}
		} finally {
			loadFromUriLock.unlock();
		}

		if (checkTaskIsNotActual() || checkTaskIsInterrupted()) return;

		DisplayBitmapTask displayBitmapTask = new DisplayBitmapTask(bmp, imageLoadingInfo, engine);
		displayBitmapTask.setLoggingEnabled(loggingEnabled);
		handler.post(displayBitmapTask);
	}

4.　本地loadBitmap

5. 判读是否存内存，如果需要存内存则存map

6.处理图片

7.显示图片