mobios.util
Interface ObjectIOManager

All Known Implementing Classes:

MckoiObjectIOManager

public interface ObjectIOManager

This is an interface for object input/output management. An implementation of this interface should be backed by a stream (file, memory, socket...). It should be able to do I/O of object on the stream.

Version:

2006.05.12

Author:

Rui Mao, Willard

Method Summary

void	close() Closes the backing stream.
void	flush() Flushes the backing stream.
Iterator	iterator()
boolean	open() Opens the backing stream.
Object	readObject(long pointer) Reads a previously written object at a given position.
Object	readPersistObject(long pointer) Reads a previously written object at a given position, and holds this object in memory for the duration of the program.
Object	removeObject(long pointer) Deletes an object from the underlying stream.
long	size()
long	writeObject(Object object) Writes a new object to the underlying stream.
Object	writeObject(Object object, long pointer) Writes an object to a given position in the underlying stream.

Method Detail

open

boolean open()

Opens the backing stream. Makes the manager ready for I/O operations.

Returns:

boolean true is sucessfully opened, otherwise false

flush

void flush()
           throws IOException

Flushes the backing stream. Saves all unsaved modifications.

Throws:

IOException

close

void close()

Closes the backing stream.

readObject

Object readObject(long pointer)
                  throws IOException,
                         ClassNotFoundException,
                         InstantiationException,
                         IllegalAccessException

Reads a previously written object at a given position.

Parameters:

pointer - the pointer to the object to be read from the underlying stream. The value is returned when the object is first written to the stream with writeObject(java.lang.Object, long)

Returns:

the object that has been read

Throws:

IOException

ClassNotFoundException

InstantiationException

IllegalAccessException

readPersistObject

Object readPersistObject(long pointer)
                         throws IOException,
                                ClassNotFoundException,
                                InstantiationException,
                                IllegalAccessException

Reads a previously written object at a given position, and holds this object in memory for the duration of the program.

Parameters:

pointer - the pointer to the object to be read in the underlying stream. The value is returned when the object is first written to the stream with writeObject(java.lang.Object, long)

Returns:

the object that has been read

Throws:

IOException

ClassNotFoundException

InstantiationException

IllegalAccessException

writeObject

Object writeObject(Object object,
                   long pointer)
                   throws IOException,
                          ClassNotFoundException

Writes an object to a given position in the underlying stream. This method modifies a previously written object at the given position.

Parameters:

object - the object to be written, cannot be null.

pointer - pointer to the underlying stream

Returns:

the original object that is overwritten.

Throws:

IOException

ClassNotFoundException

writeObject

long writeObject(Object object)
                 throws IOException

Writes a new object to the underlying stream.

Parameters:

object - the object to be added to the stream

Returns:

the pointer to the object in the stream.

Throws:

IOException

removeObject

Object removeObject(long pointer)
                    throws IOException,
                           ClassNotFoundException,
                           InstantiationException,
                           IllegalAccessException

Deletes an object from the underlying stream.

Parameters:

pointer - pointer to the object to be deleted in the underlying stream.

Returns:

the object be deleted

Throws:

IOException

ClassNotFoundException

InstantiationException

IllegalAccessException

size

long size()
          throws IOException

Returns:

the number of objects in the underlying stream

Throws:

IOException

iterator

Iterator iterator()

Returns:

an Iterator over all of the Areas in the store