Interface ExtractorInput

  • All Superinterfaces:
    DataReader
    All Known Implementing Classes:
    DefaultExtractorInput, FakeExtractorInput, ForwardingExtractorInput

    public interface ExtractorInput
    extends DataReader
    Provides data to be consumed by an Extractor.

    This interface provides two modes of accessing the underlying input. See the subheadings below for more info about each mode.

    • The read()/peek() and skip() methods provide InputStream-like byte-level access operations.
    • The read/skip/peekFully() and advancePeekPosition() methods assume the user wants to read an entire block/frame/header of known length.

    InputStream-like methods

    The read()/peek() and skip() methods provide InputStream-like byte-level access operations. The length parameter is a maximum, and each method returns the number of bytes actually processed. This may be less than length because the end of the input was reached, or the method was interrupted, or the operation was aborted early for another reason.

    Block-based methods

    The read/skip/peekFully() and advancePeekPosition() methods assume the user wants to read an entire block/frame/header of known length.

    These methods all have a variant that takes a boolean allowEndOfInput parameter. This parameter is intended to be set to true when the caller believes the input might be fully exhausted before the call is made (i.e. they've previously read/skipped/peeked the final block/frame/header). It's not intended to allow a partial read (i.e. greater than 0 bytes, but less than length) to succeed - this will always throw an EOFException from these methods (a partial read is assumed to indicate a malformed block/frame/header - and therefore a malformed file).

    The expected behaviour of the block-based methods is therefore:

    • Already at end-of-input and allowEndOfInput=false: Throw EOFException.
    • Already at end-of-input and allowEndOfInput=true: Return false.
    • Encounter end-of-input during read/skip/peek/advance: Throw EOFException (regardless of allowEndOfInput).
    • Method Detail

      • read

        int read​(byte[] target,
                 int offset,
                 int length)
          throws IOException
        Reads up to length bytes from the input and resets the peek position.

        This method blocks until at least one byte of data can be read, the end of the input is detected, or an exception is thrown.

        Specified by:
        read in interface DataReader
        Parameters:
        target - A target array into which data should be written.
        offset - The offset into the target array at which to write.
        length - The maximum number of bytes to read from the input.
        Returns:
        The number of bytes read, or C.RESULT_END_OF_INPUT if the input has ended.
        Throws:
        IOException - If an error occurs reading from the input.
      • readFully

        boolean readFully​(byte[] target,
                          int offset,
                          int length,
                          boolean allowEndOfInput)
                   throws IOException
        Like read(byte[], int, int), but reads the requested length in full.
        Parameters:
        target - A target array into which data should be written.
        offset - The offset into the target array at which to write.
        length - The number of bytes to read from the input.
        allowEndOfInput - True if encountering the end of the input having read no data is allowed, and should result in false being returned. False if it should be considered an error, causing an EOFException to be thrown. See note in class Javadoc.
        Returns:
        True if the read was successful. False if allowEndOfInput=true and the end of the input was encountered having read no data.
        Throws:
        EOFException - If the end of input was encountered having partially satisfied the read (i.e. having read at least one byte, but fewer than length), or if no bytes were read and allowEndOfInput is false.
        IOException - If an error occurs reading from the input.
      • readFully

        void readFully​(byte[] target,
                       int offset,
                       int length)
                throws IOException
        Parameters:
        target - A target array into which data should be written.
        offset - The offset into the target array at which to write.
        length - The number of bytes to read from the input.
        Throws:
        EOFException - If the end of input was encountered.
        IOException - If an error occurs reading from the input.
      • skip

        int skip​(int length)
          throws IOException
        Like read(byte[], int, int), except the data is skipped instead of read.
        Parameters:
        length - The maximum number of bytes to skip from the input.
        Returns:
        The number of bytes skipped, or C.RESULT_END_OF_INPUT if the input has ended.
        Throws:
        IOException - If an error occurs reading from the input.
      • skipFully

        boolean skipFully​(int length,
                          boolean allowEndOfInput)
                   throws IOException
        Like readFully(byte[], int, int, boolean), except the data is skipped instead of read.
        Parameters:
        length - The number of bytes to skip from the input.
        allowEndOfInput - True if encountering the end of the input having skipped no data is allowed, and should result in false being returned. False if it should be considered an error, causing an EOFException to be thrown. See note in class Javadoc.
        Returns:
        True if the skip was successful. False if allowEndOfInput=true and the end of the input was encountered having skipped no data.
        Throws:
        EOFException - If the end of input was encountered having partially satisfied the skip (i.e. having skipped at least one byte, but fewer than length), or if no bytes were skipped and allowEndOfInput is false.
        IOException - If an error occurs reading from the input.
      • skipFully

        void skipFully​(int length)
                throws IOException
        Like readFully(byte[], int, int), except the data is skipped instead of read.

        Encountering the end of input is always considered an error, and will result in an EOFException being thrown.

        Parameters:
        length - The number of bytes to skip from the input.
        Throws:
        EOFException - If the end of input was encountered.
        IOException - If an error occurs reading from the input.
      • peek

        int peek​(byte[] target,
                 int offset,
                 int length)
          throws IOException
        Peeks up to length bytes from the peek position. The current read position is left unchanged.

        This method blocks until at least one byte of data can be peeked, the end of the input is detected, or an exception is thrown.

        Calling resetPeekPosition() resets the peek position to equal the current read position, so the caller can peek the same data again. Reading or skipping also resets the peek position.

        Parameters:
        target - A target array into which data should be written.
        offset - The offset into the target array at which to write.
        length - The maximum number of bytes to peek from the input.
        Returns:
        The number of bytes peeked, or C.RESULT_END_OF_INPUT if the input has ended.
        Throws:
        IOException - If an error occurs peeking from the input.
      • peekFully

        boolean peekFully​(byte[] target,
                          int offset,
                          int length,
                          boolean allowEndOfInput)
                   throws IOException
        Like peek(byte[], int, int), but peeks the requested length in full.
        Parameters:
        target - A target array into which data should be written.
        offset - The offset into the target array at which to write.
        length - The number of bytes to peek from the input.
        allowEndOfInput - True if encountering the end of the input having peeked no data is allowed, and should result in false being returned. False if it should be considered an error, causing an EOFException to be thrown. See note in class Javadoc.
        Returns:
        True if the peek was successful. False if allowEndOfInput=true and the end of the input was encountered having peeked no data.
        Throws:
        EOFException - If the end of input was encountered having partially satisfied the peek (i.e. having peeked at least one byte, but fewer than length), or if no bytes were peeked and allowEndOfInput is false.
        IOException - If an error occurs peeking from the input.
      • peekFully

        void peekFully​(byte[] target,
                       int offset,
                       int length)
                throws IOException
        Parameters:
        target - A target array into which data should be written.
        offset - The offset into the target array at which to write.
        length - The number of bytes to peek from the input.
        Throws:
        EOFException - If the end of input was encountered.
        IOException - If an error occurs peeking from the input.
      • advancePeekPosition

        boolean advancePeekPosition​(int length,
                                    boolean allowEndOfInput)
                             throws IOException
        Advances the peek position by length bytes. Like peekFully(byte[], int, int, boolean) except the data is skipped instead of read.
        Parameters:
        length - The number of bytes by which to advance the peek position.
        allowEndOfInput - True if encountering the end of the input before advancing is allowed, and should result in false being returned. False if it should be considered an error, causing an EOFException to be thrown. See note in class Javadoc.
        Returns:
        True if advancing the peek position was successful. False if allowEndOfInput=true and the end of the input was encountered before advancing over any data.
        Throws:
        EOFException - If the end of input was encountered having partially advanced (i.e. having advanced by at least one byte, but fewer than length), or if the end of input was encountered before advancing and allowEndOfInput is false.
        IOException - If an error occurs advancing the peek position.
      • advancePeekPosition

        void advancePeekPosition​(int length)
                          throws IOException
        Advances the peek position by length bytes. Like peekFully(byte[], int, int) except the data is skipped instead of read.
        Parameters:
        length - The number of bytes to peek from the input.
        Throws:
        EOFException - If the end of input was encountered.
        IOException - If an error occurs peeking from the input.
      • resetPeekPosition

        void resetPeekPosition()
        Resets the peek position to equal the current read position.
      • getPeekPosition

        long getPeekPosition()
        Returns the current peek position (byte offset) in the stream.
        Returns:
        The peek position (byte offset) in the stream.
      • getPosition

        long getPosition()
        Returns the current read position (byte offset) in the stream.
        Returns:
        The read position (byte offset) in the stream.
      • getLength

        long getLength()
        Returns the length of the source stream, or C.LENGTH_UNSET if it is unknown.
        Returns:
        The length of the source stream, or C.LENGTH_UNSET.
      • setRetryPosition

        <E extends Throwable> void setRetryPosition​(long position,
                                                    E e)
                                             throws E extends Throwable
        Called when reading fails and the required retry position is different from the last position. After setting the retry position it throws the given Throwable.
        Type Parameters:
        E - Type of Throwable to be thrown.
        Parameters:
        position - The required retry position.
        e - Throwable to be thrown.
        Throws:
        E - The given Throwable object.
        E extends Throwable