com.msi.comms.bytebuffer
Class FixedBuffer

java.lang.Object
  |
  +--com.msi.comms.bytebuffer.FixedBuffer

All Implemented Interfaces:

java.io.Serializable

public class FixedBuffer

extends java.lang.Object

implements java.io.Serializable

FixedBuffer provides a model of a fixed length byte buffer as is commonly used in communications between various systems. The buffers modeled here have:

• Fixed total length, though padding may be used
• Positional values, though internal padding may be used

This implementation supports construction of the various buffer formats that might be used in a communications protocol without hard-coding low-level access.

Given a buffer layout:

 msgid  cmd   parm 1    parm 2
[-----][---][--------][--------]

    FixedBuffer buf = new FixedBuffer(24);
    buf.addCell("Message ID", 5);
    buf.addCell("Command", 3);
    buf.addCell("Parameter 1", 8);
    buf.addCell("Parameter 2", 8);

Version:

1.0

Author:

Ken Thompson

See Also:

Serialized Form

Field Summary

protected byte[]	buffer
private java.util.ArrayList	cells
private int	length

Constructor Summary

FixedBuffer(int length)
Creates a new FixedBuffer instance.

Method Summary

int	addCell(java.lang.String name, int length) addCell add a cell to the end of the existing cells defining the buffer format.
void	clearBuffer(byte b) clearBuffer set all bytes in the buffer to the given value.
byte[]	getBytes() getBytes return a copy of the buffer bytes.
byte[]	getCell(int index) getCell retrieve the buffer contents specified by cell index.
double	getCellDouble(int index) getCellDouble retrieve the buffer contents specified by cell index.
int	getCellInt(int index) getCellInt retrieve the buffer contents specified by cell index.
java.util.ArrayList	getCells() Get the value of cells.
java.lang.String	getCellText(int index) getCellText retrieve the buffer contents specified by cell index.
java.lang.String	getCellTextTrim(int index) getCellTextTrim retrieve the buffer contents specified by cell index.
int	getLength() Get the value of length.
private int	nextOffset() nextOffset calculate the index of the next available offset into the buffer.
void	setBuffer(byte[] v) setBuffer copy as much of the supplied data as possible into the buffer.
void	setCell(int index, byte[] value) setCell copy the supplied bytes into the fixed buffer at the location defined by the cell at the supplied index.
void	setCells(java.util.ArrayList v) Set the value of cells.
void	setLength(int v) Set the value of length.
java.lang.String	toString() toString presentation of class state.

Methods inherited from class java.lang.Object

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

Field Detail

length

private int length

buffer

protected byte[] buffer

cells

private java.util.ArrayList cells

Constructor Detail

FixedBuffer

public FixedBuffer(int length)

Creates a new FixedBuffer instance.

Parameters:

length - an int of the fixed buffer in bytes.

Method Detail

setBuffer

public void setBuffer(byte[] v)

setBuffer copy as much of the supplied data as possible into the buffer.

Parameters:

v - a byte[] value

clearBuffer

public void clearBuffer(byte b)

clearBuffer set all bytes in the buffer to the given value.

Parameters:

b - a byte value

getBytes

public byte[] getBytes()

getBytes return a copy of the buffer bytes.

Returns:

a byte[] value

addCell

public int addCell(java.lang.String name,
                   int length)
            throws java.lang.Exception

addCell add a cell to the end of the existing cells defining the buffer format.

Parameters:

name - a String name for the cell.

length - an int length in bytes for the cell.

Returns:

an int representing the index of the new cell.

java.lang.Exception

setCell

public void setCell(int index,
                    byte[] value)
             throws java.lang.Exception

setCell copy the supplied bytes into the fixed buffer at the location defined by the cell at the supplied index.

Parameters:

index - an int value

value - a byte[] value

Throws:

java.lang.Exception - if an error occurs

getCell

public byte[] getCell(int index)
               throws java.lang.Exception

getCell retrieve the buffer contents specified by cell index.

Parameters:

index - an int value

Returns:

a byte[] value

Throws:

java.lang.Exception - if an error occurs

getCellText

public java.lang.String getCellText(int index)
                             throws java.lang.Exception

getCellText retrieve the buffer contents specified by cell index.

Parameters:

index - an int value

Throws:

java.lang.Exception - if an error occurs

getCellTextTrim

public java.lang.String getCellTextTrim(int index)
                                 throws java.lang.Exception

getCellTextTrim retrieve the buffer contents specified by cell index.

Parameters:

index - an int value

Throws:

java.lang.Exception - if an error occurs

getCellInt

public int getCellInt(int index)
               throws java.lang.Exception

getCellInt retrieve the buffer contents specified by cell index.

Parameters:

index - an int value

Throws:

java.lang.Exception - if an error occurs

getCellDouble

public double getCellDouble(int index)
                     throws java.lang.Exception

getCellDouble retrieve the buffer contents specified by cell index.

Parameters:

index - an int value

Throws:

java.lang.Exception - if an error occurs

toString

public java.lang.String toString()

toString presentation of class state.

Overrides:

toString in class java.lang.Object

Returns:

a String value

nextOffset

private int nextOffset()

nextOffset calculate the index of the next available offset into the buffer.

Returns:

an int index of the next available byte.

getLength

public int getLength()

Get the value of length.

Returns:

value of length.

setLength

public void setLength(int v)

Set the value of length.

Parameters:

v - Value to assign to length.

getCells

public java.util.ArrayList getCells()

Get the value of cells.

Returns:

value of cells.

setCells

public void setCells(java.util.ArrayList v)

Set the value of cells.

Parameters:

v - Value to assign to cells.