com.bumptech.glide.load.data
Interface DataFetcher<T>

Type Parameters:

T - The type of data to be loaded (InputStream, byte[], File etc).

All Known Implementing Classes:

AssetPathFetcher, ByteArrayFetcher, FileDescriptorAssetPathFetcher, FileDescriptorLocalUriFetcher, HttpUrlFetcher, LocalUriFetcher, MediaStoreThumbFetcher, StreamAssetPathFetcher, StreamLocalUriFetcher

public interface DataFetcher<T>

An interface for lazily retrieving data that can be used to load a resource. A new instance is created per resource load by ModelLoader. loadData(Priority) may or may not be called for any given load depending on whether or not the corresponding resource is cached. Cancel also may or may not be called. If loadData(Priority) is called, then so cleanup() will be called.

Method Summary

void	cancel() A method that will be called when a load is no longer relevant and has been cancelled.
void	cleanup() Cleanup or recycle any resources used by this data fetcher.
String	getId() Returns a string uniquely identifying the data that this fetcher will fetch including the specific size.
T	loadData(Priority priority) Asynchronously fetch data from which a resource can be decoded.

Method Detail

loadData

T loadData(Priority priority)
           throws Exception

Asynchronously fetch data from which a resource can be decoded. This will always be called on background thread so it is safe to perform long running tasks here. Any third party libraries called must be thread safe since this method will be called from a thread in a ExecutorService that may have more than one background thread. This method will only be called when the corresponding resource is not in the cache.

Note - this method will be run on a background thread so blocking I/O is safe.

Parameters:

priority - The priority with which the request should be completed.

Throws:

Exception

See Also:

where the data retuned will be cleaned up

cleanup

void cleanup()

Cleanup or recycle any resources used by this data fetcher. This method will be called in a finally block after the data returned by loadData(Priority) has been decoded by the ResourceDecoder.

Note - this method will be run on a background thread so blocking I/O is safe.

getId

String getId()

Returns a string uniquely identifying the data that this fetcher will fetch including the specific size.

A hash of the bytes of the data that will be fetched is the ideal id but since that is in many cases impractical, urls, file paths, and uris are normally sufficient.

Note - this method will be run on the main thread so it should not perform blocking operations and should finish quickly.

cancel

void cancel()

A method that will be called when a load is no longer relevant and has been cancelled. This method does not need to guarantee that any in process loads do not finish. It also may be called before a load starts or after it finishes.

The best way to use this method is to cancel any loads that have not yet started, but allow those that are in process to finish since its we typically will want to display the same resource in a different view in the near future.

Note - this method will be run on the main thread so it should not perform blocking operations and should finish quickly.