Package org.apache.hadoop.fs

Class FSInputStream

java.lang.Object
java.io.InputStream
org.apache.hadoop.fs.FSInputStream
All Implemented Interfaces:
Closeable, AutoCloseable, PositionedReadable, Seekable
@Public @Evolving public abstract class FSInputStream extends InputStream implements Seekable, PositionedReadable
FSInputStream is a generic old InputStream with a little bit of RAF-style seek ability.

  • Constructor Details

    • FSInputStream

      public FSInputStream()

  • Method Details

    • seek

      public abstract void seek(long pos) throws IOException
      Seek to the given offset from the start of the file. The next read() will be from that location. Can't seek past the end of the file.
      Specified by:
      seek in interface Seekable
      Parameters:
      pos - offset from the start of the file.
      Throws:
      IOException - raised on errors performing I/O.

    • getPos

      public abstract long getPos() throws IOException
      Return the current offset from the start of the file
      Specified by:
      getPos in interface Seekable
      Returns:
      offset from the start of the file.
      Throws:
      IOException - raised on errors performing I/O.

    • seekToNewSource

      public abstract boolean seekToNewSource(long targetPos) throws IOException
      Seeks a different copy of the data. Returns true if found a new source, false otherwise.
      Specified by:
      seekToNewSource in interface Seekable
      Parameters:
      targetPos - target position.
      Returns:
      true if found a new source, false otherwise.
      Throws:
      IOException - raised on errors performing I/O.

    • read

      public int read(long position, byte[] buffer, int offset, int length) throws IOException
      Description copied from interface: PositionedReadable
      Read up to the specified number of bytes, from a given position within a file, and return the number of bytes read. This does not change the current offset of a file, and is thread-safe. Warning: Not all filesystems satisfy the thread-safety requirement.
      Specified by:
      read in interface PositionedReadable
      Parameters:
      position - position within file
      buffer - destination buffer
      offset - offset in the buffer
      length - number of bytes to read
      Returns:
      actual number of bytes read; -1 means "none"
      Throws:
      IOException - IO problems.

    • validatePositionedReadArgs

      protected void validatePositionedReadArgs(long position, byte[] buffer, int offset, int length) throws EOFException
      Validation code, available for use in subclasses.
      Parameters:
      position - position: if negative an EOF exception is raised
      buffer - destination buffer
      offset - offset within the buffer
      length - length of bytes to read
      Throws:
      EOFException - if the position is negative
      IndexOutOfBoundsException - if there isn't space for the amount of data requested.
      IllegalArgumentException - other arguments are invalid.

    • readFully

      public void readFully(long position, byte[] buffer, int offset, int length) throws IOException
      Description copied from interface: PositionedReadable
      Read the specified number of bytes, from a given position within a file. This does not change the current offset of a file, and is thread-safe. Warning: Not all filesystems satisfy the thread-safety requirement.
      Specified by:
      readFully in interface PositionedReadable
      Parameters:
      position - position within file
      buffer - destination buffer
      offset - offset in the buffer
      length - number of bytes to read
      Throws:
      IOException - IO problems.
      EOFException - the end of the data was reached before the read operation completed

    • readFully

      public void readFully(long position, byte[] buffer) throws IOException
      Description copied from interface: PositionedReadable
      Read number of bytes equal to the length of the buffer, from a given position within a file. This does not change the current offset of a file, and is thread-safe. Warning: Not all filesystems satisfy the thread-safety requirement.
      Specified by:
      readFully in interface PositionedReadable
      Parameters:
      position - position within file
      buffer - destination buffer
      Throws:
      IOException - IO problems.
      EOFException - the end of the data was reached before the read operation completed

    • toString

      public String toString()
      toString method returns the superclass toString, but if the subclass implements IOStatisticsSource then those statistics are extracted and included in the output. That is: statistics of subclasses are automatically reported.
      Overrides:
      toString in class Object
      Returns:
      a string value.