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, FileDescriptorAssetPathFetcher, FileDescriptorLocalUriFetcher, HttpUrlFetcher, LocalUriFetcher, OkHttpStreamFetcher, OkHttpStreamFetcher, StreamAssetPathFetcher, StreamLocalUriFetcher, ThumbFetcher, VolleyStreamFetcher

public interface DataFetcher<T>

Lazily retrieves data that can be used to load a resource.

A new instance is created per resource load by ModelLoader. loadData(com.bumptech.glide.Priority, com.bumptech.glide.load.data.DataFetcher.DataCallback) 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(com.bumptech.glide.Priority, com.bumptech.glide.load.data.DataFetcher.DataCallback)} is called, then so cleanup() will be called.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	DataFetcher.DataCallback<T> Callback that must be called when data has been loaded and is available, or when the load fails.

Method Summary

Modifier and Type	Method and Description
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.
Class<T>	getDataClass() Returns the class of the data this fetcher will attempt to obtain.
DataSource	getDataSource() Returns the DataSource this fetcher will return data from.
void	loadData(Priority priority, DataFetcher.DataCallback<? super T> callback) Fetch data from which a resource can be decoded.

Method Detail

loadData

void loadData(Priority priority,
              DataFetcher.DataCallback<? super T> callback)

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 (or move the work to another thread) since this method will be called from a thread in a ExecutorService that may have more than one background thread.

You MUST use the DataFetcher.DataCallback once the request is complete. You are free to move the fetch work to another thread and call the callback from there.

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.

callback - The callback to use when the request is complete

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 provided by loadData(com.bumptech.glide.Priority, com.bumptech.glide.load.data.DataFetcher.DataCallback) has been decoded by the ResourceDecoder.

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

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.

getDataClass

@NonNull
Class<T> getDataClass()

Returns the class of the data this fetcher will attempt to obtain.

getDataSource

@NonNull
DataSource getDataSource()

Returns the DataSource this fetcher will return data from.