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最新推荐文章于 2025-08-21 00:08:49 发布

原创最新推荐文章于 2025-08-21 00:08:49 发布 · 731 阅读

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文章标签：

#asynchronous #imagelist #thread #hashmap #class #debugging

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本文介绍了用于在SD卡上存储和读取缓存数据的DiskCache类，并详细解释了其内部实现，包括SparseArray、Record类以及如何使用CacheService进行数据操作。此外，文章还涉及了与缓存相关的类和组件，如AlbumCache、MediaFeed等，以及OpenGL在渲染视图中的应用。

DiskCache.java

A class used to store cache data into theSD card, or read cache from it.

Fields

private LongSparseArray<Record> mIndexMap;

privatefinal LongSparseArray<RandomAccessFile> mChunkFiles

LongSparseArray: SparseArrays map longs to Objects. Unlike a normal array of Objects,there can be gaps in the indices. It is intended to be more efficient thanusing a HashMap to map Longs to Objects.

mIndexMap: a map from (long) keyto a record which indiactes the offset / size of the data stored in the chunkfile.

private static final class Record {

…

public final long timestamp;

public final int chunk;

public final int offset;

public final int size;

public final int sizeOnDisk;

}

mChunkFiles: a map from (Record.) chunkto the random access chunk files.

Methods

publicbyte[] get(long key, long timestamp)

publicvoid put(long key, byte[] data, long timestamp)

get:

put:

CacheService.java

extends IntentService

IntentService is a base class for Servicesthat handle asynchronous requests (expressedas Intents) on demand. Clients send requests through startService(Intent) calls; the service is started as needed, handles each Intent inturn using a worker thread, and stops itself when it runs out of work. To use it, extend IntentService andimplement onHandleIntent(Intent).IntentService will receive the Intents, launch a worker thread, and stop theservice as appropriate.

All requests are handled on a singleworker thread -- they may take as long as necessary (and will not block theapplication's main loop), but only one request will be processed at a time.

A class used to store cache data into the SD card, or read cachefrom it.

Fields

publicstaticfinal DiskCache sAlbumCache = new DiskCache("local-album-cache");

publicstaticfinal DiskCache sMetaAlbumCache = new DiskCache("local-meta-cache");

publicstaticfinal DiskCache sSkipThumbnailIds = new DiskCache("local-skip-cache");

privatestatic ImageList sList = null;