FileDescriptorDataSource

Artifact: androidx.media3:media3-datasource

View Source

---

Kotlin |Java

@UnstableApi
class FileDescriptorDataSource : BaseDataSource

kotlin.Any
↳	androidx.media3.datasource.BaseDataSource
	↳	androidx.media3.datasource.FileDescriptorDataSource

---

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 constructors
FileDescriptorDataSource(     fileDescriptor: FileDescriptor!,     offset: Long,     length: Long ) Creates a new instance.

Public functions
Unit	close() Closes the source.
Long	open(dataSpec: DataSpec!) Opens the source to read the specified data.
Int	read(buffer: ByteArray!, offset: Int, length: Int) Reads up to length bytes of data from the input.

Public properties
Uri?	uri

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

Public constructors

FileDescriptorDataSource

FileDescriptorDataSource(
    fileDescriptor: FileDescriptor!,
    offset: Long,
    length: Long
)

Creates a new instance.

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

Public functions

close

fun close(): Unit

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

open

fun open(dataSpec: DataSpec!): Long

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

fun read(buffer: ByteArray!, offset: Int, length: Int): Int

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
buffer: ByteArray!	A target array into which data should be written.
offset: Int	The offset into the target array at which to write.
length: Int	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

Public properties

uri

val uri: Uri?