ucar.unidata.io
Class MMapRandomAccessFile

java.lang.Object
  ucar.unidata.io.RandomAccessFile
      ucar.unidata.io.MMapRandomAccessFile

All Implemented Interfaces:

java.io.DataInput, java.io.DataOutput

public class MMapRandomAccessFile
extends RandomAccessFile

Use NIO MappedByteBuffer to implement a RandomAccessFile. Limited to 2G size.

Author:

john

Field Summary

Fields inherited from class ucar.unidata.io.RandomAccessFile

BIG_ENDIAN, bigEndian, buffer, bufferStart, cached, dataEnd, dataSize, debugAccess, debugLeaks, defaultBufferSize, endOfFile, file, filePosition, LITTLE_ENDIAN, location, openFiles, readonly

Constructor Summary

MMapRandomAccessFile(java.lang.String location, java.lang.String mode)
Constructor for in-memory "files"

Method Summary

void	close() Close the file, and release any associated system resources.
void	flush() Copy the contents of the buffer to the disk.
long	length() Get the length of the file.
int	read() Read a byte of data from the file, blocking until data is available.
protected int	readBytes(byte[] dst, int offset, int length) Read up to len bytes into an array, at a specified offset.
void	seek(long pos) Set the position in the file for the next read or write.
void	unread() Unread the last byte read.
void	write(int b) Write a byte to the file.
void	writeBytes(byte[] dst, int offset, int length) Write len bytes from an array to the file.

Methods inherited from class ucar.unidata.io.RandomAccessFile

getFD, getFilePointer, getLocation, getRandomAccessFile, isAtEndOfFile, isCached, order, read_, read, read, readBoolean, readByte, readChar, readDouble, readDouble, readFloat, readFloat, readFully, readFully, readInt, readInt, readIntUnbuffered, readLine, readLong, readLong, readShort, readShort, readString, readUnsignedByte, readUnsignedShort, readUTF, setCached, setDebugAccess, setDebugLeaks, setExtendMode, setMinLength, skipBytes, synch, toString, write, write, writeBoolean, writeBoolean, writeByte, writeBytes, writeBytes, writeChar, writeChar, writeChars, writeDouble, writeDouble, writeFloat, writeFloat, writeInt, writeInt, writeLong, writeLong, writeShort, writeShort, writeUTF

Methods inherited from class java.lang.Object

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

Constructor Detail

MMapRandomAccessFile

public MMapRandomAccessFile(java.lang.String location,
                            java.lang.String mode)
                     throws java.io.IOException

Constructor for in-memory "files"

Parameters:

location - used as a name

mode - the open mode

Throws:

java.io.IOException - on error

Method Detail

flush

public void flush()
           throws java.io.IOException

Description copied from class: RandomAccessFile

Copy the contents of the buffer to the disk.

Overrides:

flush in class RandomAccessFile

Throws:

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

close

public void close()
           throws java.io.IOException

Description copied from class: RandomAccessFile

Close the file, and release any associated system resources.

Overrides:

close in class RandomAccessFile

Throws:

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

length

public long length()

Description copied from class: RandomAccessFile

Get the length of the file. The data in the buffer (which may not have been written the disk yet) is taken into account.

Overrides:

length in class RandomAccessFile

Returns:

the length of the file in bytes.

seek

public void seek(long pos)

Description copied from class: RandomAccessFile

Set the position in the file for the next read or write.

Overrides:

seek in class RandomAccessFile

Parameters:

pos - the offset (in bytes) from the start of the file.

unread

public void unread()

Description copied from class: RandomAccessFile

Unread the last byte read. This method should not be used more than once between reading operations, or strange things might happen.

Overrides:

unread in class RandomAccessFile

read

public int read()
         throws java.io.IOException

Description copied from class: RandomAccessFile

Read a byte of data from the file, blocking until data is available.

Overrides:

read in class RandomAccessFile

Returns:

the next byte of data, or -1 if the end of the file is reached.

Throws:

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

readBytes

protected int readBytes(byte[] dst,
                        int offset,
                        int length)
                 throws java.io.IOException

Description copied from class: RandomAccessFile

Read up to len bytes into an array, at a specified offset. This will block until at least one byte has been read.

Overrides:

readBytes in class RandomAccessFile

Parameters:

dst - the byte array to receive the bytes.

offset - the offset in the array where copying will start.

length - the number of bytes to copy.

Returns:

the actual number of bytes read, or -1 if there is not more data due to the end of the file being reached.

Throws:

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

write

public void write(int b)
           throws java.io.IOException

Description copied from class: RandomAccessFile

Write a byte to the file. If the file has not been opened for writing, an IOException will be raised only when an attempt is made to write the buffer to the file.

Caveat: the effects of seek( )ing beyond the end of the file are undefined.

Specified by:

write in interface java.io.DataOutput

Overrides:

write in class RandomAccessFile

Parameters:

b - _more_

Throws:

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

writeBytes

public void writeBytes(byte[] dst,
                       int offset,
                       int length)
                throws java.io.IOException

Description copied from class: RandomAccessFile

Write len bytes from an array to the file.

Overrides:

writeBytes in class RandomAccessFile

Parameters:

dst - the array containing the data.

offset - the offset in the array to the data.

length - the length of the data.

Throws:

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