com.mucommander.io
Class RandomAccessInputStream

java.lang.Object
  java.io.InputStream
      com.mucommander.io.RandomAccessInputStream

All Implemented Interfaces:

RandomAccess, java.io.Closeable

Direct Known Subclasses:

BlockRandomInputStream, LocalFile.LocalRandomAccessInputStream, NFSFile.NFSRandomAccessInputStream, SMBFile.SMBRandomAccessInputStream

public abstract class RandomAccessInputStream
extends java.io.InputStream
implements RandomAccess

RandomAccessInputStream is an InputStream with random access. The following java.io.InputStream methods are overridden to provide an improved implementation:

• mark(int)
• reset()
• markSupported()
• skip(long)
• available()

Important: BufferedInputStream or any wrapper InputStream class that uses a read buffer CANNOT be used with a RandomAccessInputStream if the RandomAccess.seek(long) method is to be used. Doing so would corrupt the read buffer and yield to data inconsistencies.

Author:

Maxence Bernard

Constructor Summary

RandomAccessInputStream()
Creates a new RandomAccessInputStream.

Method Summary

int	available() Return the number of bytes that are available for reading, that is: RandomAccess.getLength() - RandomAccess.getOffset() - 1.
abstract void	close() Closes this stream and releases any system resources associated with the stream.
void	mark(int readLimit) Overrides InputStream.mark() to provide a working implementation of the method.
boolean	markSupported() Always returns true: mark(int) and reset() methods are supported.
abstract int	read(byte[] b, int off, int len) Reads up to len bytes of data from this file into an array of bytes.
void	readFully(byte[] b) Reads b.length bytes from this file into the byte array, starting at the current file pointer.
void	readFully(byte[] b, int off, int len) Reads exactly len bytes from this file into the byte array, starting at the current file pointer.
void	reset() Overrides InputStream.mark() to provide a working implementation of the method.
long	skip(long n) Skips (up to) the specified number of bytes and returns the number of bytes effectively skipped.

Methods inherited from class java.io.InputStream

read, read

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.mucommander.io.RandomAccess

getLength, getOffset, seek

Constructor Detail

RandomAccessInputStream

public RandomAccessInputStream()

Creates a new RandomAccessInputStream.

Method Detail

readFully

public void readFully(byte[] b)
               throws java.io.IOException

Reads b.length bytes from this file into the byte array, starting at the current file pointer. This method reads repeatedly from the file until the requested number of bytes are read. This method blocks until the requested number of bytes are read, the end of the stream is detected, or an exception is thrown.

Parameters:

b - the buffer into which the data is read.

Throws:

java.io.EOFException - if this file reaches the end before reading all the bytes.

java.io.IOException - if an I/O error occurs.

readFully

public void readFully(byte[] b,
                      int off,
                      int len)
               throws java.io.IOException

Reads exactly len bytes from this file into the byte array, starting at the current file pointer. This method reads repeatedly from the file until the requested number of bytes are read. This method blocks until the requested number of bytes are read, the end of the stream is detected, or an exception is thrown.

Parameters:

b - the buffer into which the data is read.

off - the start offset of the data.

len - the number of bytes to read.

Throws:

java.io.EOFException - if this file reaches the end before reading all the bytes.

java.io.IOException - if an I/O error occurs.

skip

public long skip(long n)
          throws java.io.IOException

Skips (up to) the specified number of bytes and returns the number of bytes effectively skipped. The exact given number of bytes will be skipped as long as the current offset as returned by RandomAccess.getOffset() plus the number of bytes to skip doesn't exceed the length of this stream as returned by RandomAccess.getLength(). If it does, all the remaining bytes will be skipped so that the offset of this stream will be positionned to RandomAccess.getLength(). Returns -1 if the offset is already positionned to the end of the stream when this method is called.

Overrides:

skip in class java.io.InputStream

Parameters:

n - number of bytes to skip

Returns:

the number of bytes that have effectively been skipped, -1 if the offset is already positionned to the end of the stream when this method is called

Throws:

java.io.IOException - if something went wrong

available

public int available()
              throws java.io.IOException

Return the number of bytes that are available for reading, that is: RandomAccess.getLength() - RandomAccess.getOffset() - 1. Since InputStream.available() returns an int and this method overrides it, a maximum of Integer.MAX_VALUE can be returned, even if this stream has more bytes available.

Overrides:

available in class java.io.InputStream

Returns:

the number of bytes that are available for reading.

Throws:

java.io.IOException - if something went wrong

mark

public void mark(int readLimit)

Overrides InputStream.mark() to provide a working implementation of the method. The given readLimit is simply ignored, the stream can be repositionned using reset() with no limit on the number of bytes read after mark() has been called.

Overrides:

mark in class java.io.InputStream

Parameters:

readLimit - this parameter has no effect and is simply ignored

reset

public void reset()
           throws java.io.IOException

Overrides InputStream.mark() to provide a working implementation of the method.

Overrides:

reset in class java.io.InputStream

Throws:

java.io.IOException - if something went wrong

markSupported

public boolean markSupported()

Always returns true: mark(int) and reset() methods are supported.

Overrides:

markSupported in class java.io.InputStream

read

public abstract int read(byte[] b,
                         int off,
                         int len)
                  throws java.io.IOException

Reads up to len bytes of data from this file into an array of bytes. This method blocks until at least one byte of input is available.

Overrides:

read in class java.io.InputStream

Parameters:

b - the buffer into which the data is read

off - the start offset of the data

len - the maximum number of bytes read

Returns:

the total number of bytes read into the buffer, or -1 if there is no more data because the end of the file has been reached.

Throws:

java.io.IOException - if an I/O error occurs

close

public abstract void close()
                    throws java.io.IOException

Closes this stream and releases any system resources associated with the stream. A closed stream cannot perform input operations and cannot be reopened.

Specified by:

close in interface RandomAccess

Specified by:

close in interface java.io.Closeable

Overrides:

close in class java.io.InputStream

Throws:

java.io.IOException - if an I/O error occurs.