FileDescriptorDataSource

Artifact: androidx.media3:media3-datasource

View Source

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Kotlin |Java

@UnstableApi
public class FileDescriptorDataSource extends BaseDataSource

java.lang.Object
↳	androidx.media3.datasource.BaseDataSource
	↳	androidx.media3.datasource.FileDescriptorDataSource

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A DataSource for reading from a FileDescriptor.

Due to limitations of file descriptors, it's only possible to have one DataSource created for a given file descriptor open at a time. The provided file descriptor must be seekable.

Unlike typical DataSource instances, each instance of this class can only read from a single FileDescriptor. Additionally, the uri passed to open is not actually used for reading data. Instead, the underlying is used for all read operations.

Summary

Public fields
@Nullable Uri	uri

Public constructors
FileDescriptorDataSource(     FileDescriptor fileDescriptor,     long offset,     long length ) Creates a new instance.

Public methods
void	close() Closes the source.
@Nullable Uri	getUri() When the source is open, returns the Uri from which data is being read.
long	open(DataSpec dataSpec) Opens the source to read the specified data.
int	read(byte[] buffer, int offset, int length) Reads up to length bytes of data from the input.

Inherited methods
From androidx.media3.datasource.BaseDataSource final void @UnstableApi addTransferListener(TransferListener transferListener) Adds a TransferListener to listen to data transfers. final void bytesTransferred(int bytesTransferred) Notifies listeners that bytes were transferred. final void transferEnded() Notifies listeners that a transfer ended. final void transferInitializing(DataSpec dataSpec) Notifies listeners that data transfer for the specified DataSpec is being initialized. final void transferStarted(DataSpec dataSpec) Notifies listeners that data transfer for the specified DataSpec started.
From androidx.media3.datasource.DataSource Map<String, List<String>> @UnstableApi getResponseHeaders() When the source is open, returns the response headers associated with the last open call.

Public fields

uri

public @Nullable Uri uri

Public constructors

FileDescriptorDataSource

public FileDescriptorDataSource(
    FileDescriptor fileDescriptor,
    long offset,
    long length
)

Creates a new instance.

Parameters
FileDescriptor fileDescriptor	The file descriptor from which to read.
long offset	The start offset of data to read.
long length	The length of data to read, or LENGTH_UNSET if not known.

Public methods

close

public void close()

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

Throws
java.io.IOException	If an error occurs closing the source.
androidx.media3.datasource.DataSourceException

getUri

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.

Returns
@Nullable Uri	The Uri from which data is being read, or null if the source is not open.

open

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.

Parameters
DataSpec dataSpec	Defines the data to be read.

Returns
long	The number of bytes that can be read from the opened source. For unbounded requests (i.e., requests where length equals LENGTH_UNSET) this value is the resolved length of the request, or LENGTH_UNSET if the length is still unresolved. For all other requests, the value returned will be equal to the request's length.

Throws
java.io.IOException	If an error occurs opening the source. DataSourceException can be thrown or used as a cause of the thrown exception to specify the reason of the error.
androidx.media3.datasource.DataSourceException

read

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.

Parameters
byte[] buffer	A target array into which data should be written.
int offset	The offset into the target array at which to write.
int length	The maximum number of bytes to read from the input.

Returns
int	The number of bytes read, or RESULT_END_OF_INPUT if the input has ended. This may be less than length because the end of the input (or available data) was reached, the method was interrupted, or the operation was aborted early for another reason.

Throws
java.io.IOException	If an error occurs reading from the input.
androidx.media3.datasource.DataSourceException