ru.biosoft.util
Class FastFileBuffer

java.lang.Object
  ru.biosoft.util.FileBuffer
      ru.biosoft.util.FastFileBuffer

public class FastFileBuffer

extends FileBuffer

Optimized by speed implementation of FileBuffer interface.

Field Summary

protected static org.apache.log4j.Category

cat

Constructor Summary

FastFileBuffer(java.io.File file)
Constructs the RandomAccessBuffer object.

FastFileBuffer(java.io.File file, int sz)
Constructs the RandomAccessBuffer object .

FastFileBuffer(java.io.RandomAccessFile rndFile)
Constructs the RandomAccessBuffer object .

FastFileBuffer(java.io.RandomAccessFile rndFile, int sz)
Constructs the RandomAccessBuffer object .

Method Summary

void	close() Closes the buffer.
protected void	finalize() Stores all buffers and closes random access file
byte	read(int pos) Reads one byte from requested position.
void	write(int pos, byte bt) Writes one byte to the requested position in the buffer.

Methods inherited from class java.lang.Object

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

Field Detail

cat

protected static org.apache.log4j.Category cat

Constructor Detail

FastFileBuffer

public FastFileBuffer(java.io.RandomAccessFile rndFile,
                      int sz)
               throws java.io.IOException

Constructs the RandomAccessBuffer object .
Creates two buffers by size sz
fills them with preceding reading

Parameters:

rndFile - random access file

sz - Size of one buffer.

Throws:

java.io.IOException - any I/O errors

FastFileBuffer

public FastFileBuffer(java.io.RandomAccessFile rndFile)
               throws java.io.IOException

Constructs the RandomAccessBuffer object .
Creates two buffers by size sz
fills them with preceding reading

Parameters:

rndFile - random access file

Throws:

java.io.IOException - any I/O errors

FastFileBuffer

public FastFileBuffer(java.io.File file,
                      int sz)
               throws java.io.IOException

Constructs the RandomAccessBuffer object .
Creates two buffers by size sz
fills them with preceding reading

Parameters:

file - random access file

sz - Size of one buffer.

Throws:

java.io.IOException - any I/O errors

FastFileBuffer

public FastFileBuffer(java.io.File file)
               throws java.io.IOException

Constructs the RandomAccessBuffer object.
Creates two buffers by size sz
fills them with preceding reading

Parameters:

file - random access file

Throws:

java.io.IOException - any I/O errors

Method Detail

read

public byte read(int pos)
          throws java.io.IOException

Reads one byte from requested position. If byte is already in any buffer then it returns. Otherwise one of two buffers is filled by new data from position pos minus half buffer size. Method selects buffer which more distant from specified position.

Specified by:

read in class FileBuffer

Parameters:

pos - position of requested byte

Returns:

requested byte

Throws:

java.io.IOException - any I/O errors

write

public void write(int pos,
                  byte bt)
           throws java.io.IOException

Writes one byte to the requested position in the buffer. If specified position maps to any region in any of the two buffers the byte is stored into the buffer. Otherwise one of the two buffers is written into file and required portion of data is read from file back into buffer so it will satisfy the requested position. Method selects buffer which more distant from specified position.

Specified by:

write in class FileBuffer

Parameters:

pos - position of requested byte

bt - stored byte

Throws:

java.io.IOException - any I/O errors

close

public void close()
           throws java.io.IOException

Closes the buffer.

Specified by:

close in class FileBuffer

Throws:

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

finalize

protected void finalize()
                 throws java.lang.Throwable

Stores all buffers and closes random access file

Throws:

java.lang.Throwable - any errors