VLC项目学习之图片缓存

Vlc在显示歌曲列表时会加载该歌曲的封面，对于图片采取了相应的缓存机制：

1.  内存缓存

2.  文件缓存

内存缓存：

采用的是LruCache,对于使用LruCache需要注意的是分配多少内存给它去存储图片。Vlc中使用了1/5的可用内存存储图片。

        // Get memory class of this device, exceeding this amount will throw an
        // OutOfMemory exception.
        final int memClass = ((ActivityManager) context.getSystemService(
                Context.ACTIVITY_SERVICE)).getMemoryClass();

        // Use 1/5th of the available memory for this 	 cache.
        final int cacheSize = 1024 * 1024 * memClass / 5;

        Log.d(TAG, "LRUCache size sets to " + cacheSize);

        mMemCache = new LruCache<String, Bitmap>(cacheSize) {

            @Override
            protected int sizeOf(String key, Bitmap value) {
                return value.getRowBytes() * value.getHeight();
            }

        };

protected int sizeOf(String key, Bitmap value) {
                return value.getRowBytes() * value.getHeight();
            }

protected int sizeOf(Bitmap data) {
       int size = 0;
       if (Build.VERSION.SDK_INT < Build.VERSION_CODES.HONEYCOMB_MR1) {
	     size = value.getRowBytes() * value.getHeight();
	} else if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
	     size = value.getByteCount();
	} else {
	     size = value.getAllocationByteCount();
	}
      return size;
 }

不清楚为什么老版本用 value.getRowBytes() * value.getHeight()计算图片的size。 

文件缓存：

private static void writeBitmap(Bitmap bitmap, String path)
			throws IOException {
		OutputStream out = null;
		try {
			File file = new File(path);
			if (file.exists() && file.length() > 0)
				return;
			out = new BufferedOutputStream(new FileOutputStream(file), 4096);
			if (bitmap != null)
				bitmap.compress(CompressFormat.JPEG, 90, out);
		} catch (Exception e) {
			Log.e(TAG, "writeBitmap failed : " + e.getMessage());
		} finally {
			if (out != null) {
				out.close();
			}
		}
	}

VLC项目学习之图片缓存,布布扣,bubuko.com

VLC项目学习之图片缓存

原文：http://blog.csdn.net/longwuxu/article/details/20845599