ru.biosoft.util
Class SoftFileBuffer

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

public class SoftFileBuffer

extends FileBuffer

Optimized by memory size implementation of FileBuffer interface. SoftFileBuffer provides buffered reading/writing of random access file Created buffers are based on SoftReference memory allocation.

Nested Class Summary

protected class

SoftFileBuffer.Buffer

Field Summary

protected static org.apache.log4j.Category	cat
protected java.io.RandomAccessFile	randomFile

Constructor Summary

SoftFileBuffer(java.io.File file)
Constructs the RandomAccessBuffer object using specified file .

SoftFileBuffer(java.io.File file, int sz)
Constructs the RandomAccessBuffer object using specified file and size of buffer.

SoftFileBuffer(java.io.RandomAccessFile rndFile)
Constructs the RandomAccessBuffer object using specified RandomAccessFile.

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

Method Summary

void	close() Closes the buffer.
protected void	finalize() 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

randomFile

protected java.io.RandomAccessFile randomFile

Constructor Detail

SoftFileBuffer

public SoftFileBuffer(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 error

SoftFileBuffer

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

Constructs the RandomAccessBuffer object using specified RandomAccessFile.

Parameters:

rndFile - specified random access file.

Throws:

java.io.IOException - If any I/O error.

SoftFileBuffer

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

Constructs the RandomAccessBuffer object using specified file and size of buffer.

Parameters:

file - specified file.

sz - size of each buffer

Throws:

java.io.IOException - If any I/O error.

SoftFileBuffer

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

Constructs the RandomAccessBuffer object using specified file .

Parameters:

file - specified file.

Throws:

java.io.IOException - If any I/O error.

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 - If 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 - if any I/O errors

finalize

protected void finalize()
                 throws java.lang.Throwable

Closes random access file

Throws:

java.lang.Throwable

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.