com.nt.udc.util.state

Class StateBuffer

java.lang.Object

com.nt.udc.util.state.StateBuffer

public class StateBuffer
extends java.lang.Object

The StateBuffer class is responsible for holding small amounts of state data for any number of objects. The user may add state data as needed, and then invoke the write() call to persist the data to disk. The state data is immutable, therefore, it cannot be changed once it has been added to the buffer. The user must either reset() the buffer, or create a new StateBuffer object if he needs to re-write data. This is for efficiency's sake, not flexibility. The user may query a state's data at a later time using the getStateData(...) call.

Constructor Summary

Constructors

Constructor and Description
StateBuffer(java.io.File stateBufferFile, boolean isNewFile) Creates a state buffer with the given file.

Method Summary

Modifier and Type	Method and Description
void	addState(java.lang.String className, java.lang.String tag, byte[] data) Adds state information for a given item, where the item is described by its originating class, tag description, and state data.
byte[]	getStateData(java.lang.String className, java.lang.String tag) Retrieves a state item's data according to class name and tag descriptor.
static void	main(java.lang.String[] args) Prints the contents of a state buffer file.
void	reset() Resets the state data to empty.
java.lang.String	toString() Converts all state data and meta-data to a String.
void	write() Writes the state data to disk.
void	writeTo(java.io.OutputStream output) Writes the state data to the given OutputStream.

Methods inherited from class java.lang.Object

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

Constructor Detail

StateBuffer

public StateBuffer(java.io.File stateBufferFile,
                   boolean isNewFile)
            throws java.io.IOException

Creates a state buffer with the given file.

Parameters:

stateBufferFile - Output file to use

isNewFile - Should the file be treated as as a new buffer file?

Throws:

java.io.IOException

Method Detail

addState

public void addState(java.lang.String className,
                     java.lang.String tag,
                     byte[] data)

Adds state information for a given item, where the item is described by its originating class, tag description, and state data.

Parameters:

className - Originating class name

tag - Tag description if state item

data - State data

write

public void write()
           throws java.io.IOException

Writes the state data to disk.

Throws:

java.io.IOException

writeTo

public void writeTo(java.io.OutputStream output)
             throws java.io.IOException

Writes the state data to the given OutputStream.

Parameters:

output - Output stream for writing.

Throws:

java.io.IOException

reset

public void reset()

Resets the state data to empty.

getStateData

public byte[] getStateData(java.lang.String className,
                           java.lang.String tag)

Retrieves a state item's data according to class name and tag descriptor.

Parameters:

className - Originating class name

tag - Tag descriptor

Returns:

state data

toString

public java.lang.String toString()

Converts all state data and meta-data to a String.

Overrides:

toString in class java.lang.Object

main

public static void main(java.lang.String[] args)

Prints the contents of a state buffer file.

Parameters:

args - State buffer file name