org.apache.hadoop.fs
Class FSDataInputStream

java.lang.Object
  java.io.InputStream
      java.io.FilterInputStream
          java.io.DataInputStream
              org.apache.hadoop.fs.FSDataInputStream

All Implemented Interfaces:

Closeable, DataInput, HasFileDescriptor, PositionedReadable, Seekable

public class FSDataInputStream
extends DataInputStream
implements Seekable, PositionedReadable, Closeable, HasFileDescriptor

Utility that wraps a FSInputStream in a DataInputStream and buffers input through a BufferedInputStream.

Field Summary

Fields inherited from class java.io.FilterInputStream

in

Constructor Summary

FSDataInputStream(InputStream in)

Method Summary

FileDescriptor	getFileDescriptor()
long	getPos() Return the current offset from the start of the file
int	read(long position, byte[] buffer, int offset, int length) Read upto the specified number of bytes, from a given position within a file, and return the number of bytes read.
void	readFully(long position, byte[] buffer) Read number of bytes equalt to the length of the buffer, from a given position within a file.
void	readFully(long position, byte[] buffer, int offset, int length) Read the specified number of bytes, from a given position within a file.
void	seek(long desired) Seek to the given offset from the start of the file.
boolean	seekToNewSource(long targetPos) Seeks a different copy of the data.

Methods inherited from class java.io.DataInputStream

read, read, readBoolean, readByte, readChar, readDouble, readFloat, readFully, readFully, readInt, readLine, readLong, readShort, readUnsignedByte, readUnsignedShort, readUTF, readUTF, skipBytes

Methods inherited from class java.io.FilterInputStream

available, close, mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface java.io.Closeable

close

Constructor Detail

FSDataInputStream

public FSDataInputStream(InputStream in)
                  throws IOException

Throws:

IOException

Method Detail

seek

public void seek(long desired)
          throws IOException

Description copied from interface: Seekable

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

Throws:

IOException

getPos

public long getPos()
            throws IOException

Description copied from interface: Seekable

Return the current offset from the start of the file

Specified by:

getPos in interface Seekable

Throws:

IOException

read

public int read(long position,
                byte[] buffer,
                int offset,
                int length)
         throws IOException

Description copied from interface: PositionedReadable

Read upto 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.

Specified by:

read in interface PositionedReadable

Throws:

IOException

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.

Specified by:

readFully in interface PositionedReadable

Throws:

IOException

readFully

public void readFully(long position,
                      byte[] buffer)
               throws IOException

Description copied from interface: PositionedReadable

Read number of bytes equalt 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.

Specified by:

readFully in interface PositionedReadable

Throws:

IOException

seekToNewSource

public boolean seekToNewSource(long targetPos)
                        throws IOException

Description copied from interface: Seekable

Seeks a different copy of the data. Returns true if found a new source, false otherwise.

Specified by:

seekToNewSource in interface Seekable

Throws:

IOException

getFileDescriptor

public FileDescriptor getFileDescriptor()
                                 throws IOException

Specified by:

getFileDescriptor in interface HasFileDescriptor

Returns:

the FileDescriptor

Throws:

IOException