CacheDataSource

public static final int CACHE_IGNORED_REASON_ERROR = 0

Cache ignored due to a cache related error.

public static final int CACHE_IGNORED_REASON_UNSET_LENGTH = 1

Cache ignored due to a request with an unset length.

public static final int FLAG_BLOCK_ON_CACHE = 1

A flag indicating whether we will block reads if the cache key is locked. If unset then data is read from upstream if the cache key is locked, regardless of whether the data is cached.

public static final int FLAG_IGNORE_CACHE_FOR_UNSET_LENGTH_REQUESTS = 4

A flag indicating that the cache should be bypassed for requests whose lengths are unset. This flag is provided for legacy reasons only.

public static final int FLAG_IGNORE_CACHE_ON_ERROR = 2

A flag indicating whether the cache is bypassed following any cache related error. If set then cache related exceptions may be thrown for one cycle of open, read and close calls. Subsequent cycles of these calls will then bypass the cache.

public CacheDataSource(Cache cache, @Nullable DataSource upstreamDataSource)

Constructs an instance with default DataSource and DataSink instances for reading and writing the cache.

public CacheDataSource(
    Cache cache,
    @Nullable DataSource upstreamDataSource,
    @CacheDataSource.Flags int flags
)

Constructs an instance with default DataSource and DataSink instances for reading and writing the cache.

public CacheDataSource(
    Cache cache,
    @Nullable DataSource upstreamDataSource,
    DataSource cacheReadDataSource,
    @Nullable DataSink cacheWriteDataSink,
    @CacheDataSource.Flags int flags,
    @Nullable CacheDataSource.EventListener eventListener
)

Constructs an instance with arbitrary DataSource and DataSink instances for reading and writing the cache. One use of this constructor is to allow data to be transformed before it is written to disk.

public CacheDataSource(
    Cache cache,
    @Nullable DataSource upstreamDataSource,
    DataSource cacheReadDataSource,
    @Nullable DataSink cacheWriteDataSink,
    @CacheDataSource.Flags int flags,
    @Nullable CacheDataSource.EventListener eventListener,
    @Nullable CacheKeyFactory cacheKeyFactory
)

Constructs an instance with arbitrary DataSource and DataSink instances for reading and writing the cache. One use of this constructor is to allow data to be transformed before it is written to disk.

public void addTransferListener(TransferListener transferListener)

Adds a TransferListener to listen to data transfers. This method is not thread-safe.

public void close()

Closes the source. This method must be called even if the corresponding call to open threw an IOException.

public Cache getCache()

Returns the Cache used by this instance.

public CacheKeyFactory getCacheKeyFactory()

Returns the CacheKeyFactory used by this instance.

public Map<String, List<String>> getResponseHeaders()

When the source is open, returns the response headers associated with the last open call. Otherwise, returns an empty map.

Key look-up in the returned map is case-insensitive.

public @Nullable Uri getUri()

When the source is open, returns the Uri from which data is being read. The returned Uri will be identical to the one passed open in the DataSpec unless redirection has occurred. If redirection has occurred, the Uri after redirection is returned.

public long open(DataSpec dataSpec)

Opens the source to read the specified data. If an IOException is thrown, callers must still call close to ensure that any partial effects of the invocation are cleaned up.

The following edge case behaviors apply:

• If the requested position is within the resource, but the requested length extends beyond the end of the resource, then open will succeed and data from the requested position to the end of the resource will be made available through read.
• If the requested position is equal to the length of the resource, then open will succeed, and read will immediately return RESULT_END_OF_INPUT.
• If the requested position is greater than the length of the resource, then open will throw an IOException for which isCausedByPositionOutOfRange will be true.

public int read(byte[] buffer, int offset, int length)

Reads up to length bytes of data from the input.

If readLength is zero then 0 is returned. Otherwise, if no data is available because the end of the opened range has been reached, then RESULT_END_OF_INPUT is returned. Otherwise, the call will block until at least one byte of data has been read and the number of bytes read is returned.