ru.biosoft.util
Class SoftFileBuffer

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.

public SoftFileBuffer(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:

IOException - any I/O error

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

Constructs the RandomAccessBuffer object using specified RandomAccessFile.

Parameters:

rndFile - specified random access file.

Throws:

IOException - If any I/O error.

public SoftFileBuffer(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:

IOException If - any I/O error.

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

Constructs the RandomAccessBuffer object using specified file .

Parameters:

file - specified file.

Throws:

IOException If - any I/O error.

public void close()
            throws java.io.IOException

Closes the buffer.

Throws:

IOException - if an I/O error occurs.

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.

Parameters:

pos - position of requested byte

Returns: requested byte

Throws:

IOException - If any I/O errors

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.

Parameters:

pos - position of requested byte

bt - stored byte

Throws:

IOException - if any I/O errors

Association Links

to Class org.apache.log4j.Category

to Class java.io.RandomAccessFile

to Class java.lang.ref.SoftReference

to Class java.lang.ref.SoftReference