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java.net
Class ZObject  

java.lang.Object
  java.net.ZObject

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public class ZObject

extends java.lang.Object

This class implements an object type suitable to be serialized in a non-standard way. To minimize the overhead that can occur in standard serialization, this class provides methods to serialize and deserialize objects minimizing the overhead. This class can represents compressed, uncompressed and ack objects.

Version:

1.0

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Field Summary
static byte	ACK_TYPE
static byte	COMPR_TYPE
protected  byte[]	data           The data payload this object carries.
(package private) static byte[]	magic           This static field represents the magic sequence that distinguishes serialized ZObject instances.
protected  long	seqnum           The sequence number that distinguishes that object.
protected  byte	type           This field can be one of the following type: ACK_TYPE for ack object, COMPR_TYPE for compressed object, UNCOMPR_TYPE for uncompressed object (actually nonsense).
static byte	UNCOMPR_TYPE

 

Constructor Summary

ZObject(byte[] _data)           Constructor used to build a compressed object with a specific data payload.

ZObject(byte[] _data, byte type)           Constructor used to build a generic ZObject instance.

ZObject(DatagramPacket packet)           Constructor used to build an object by deserializing data coming from the buffer contained in the passed datagram.

ZObject(java.io.InputStream in)           Constructor used to build an object by deserializing data coming from an input stream, tipically a socket input stream.

ZObject(long seqnum)           Constructor used to build an ack object with a well-defined sequence number.

 

Method Summary
protected  void	create(byte[] _data, byte type)           This method is responsible for generic object creation and it's an utility method used by constructors.
protected static long	deserialize(byte[] buf)           This method decodes an array of four bytes into a long value.
boolean	dump(byte[] buf, int len)
byte[]	getData()           This method returns the carried data payload.
long	getSeqNum()           This method returns the carried sequence number.
protected static long	positivize(long x)           This method positivize the passed long using steps of value 256.
byte[]	prepareData()           This method actually performs encoding on the internal object using a ByteArrayOutputStream as a container where internal fields get written into.
protected static byte[]	serialize(long num)           This method converts a passed long into a sequence of four bytes that can be written to an output stream.
void	setData(byte[] dat)           This method decodes the passed byte array trying to deserialize a ZObject instance.
void	setData(java.io.InputStream in)           This method decodes data from the input stream trying to deserialize a ZObject instance.
java.lang.String	toString()           Convert this Object to a human-readable String.

 

Methods inherited from class java.lang.Object

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

 

Field Detail

magic

static byte[] magic

This static field represents the magic sequence that distinguishes serialized ZObject instances.

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data

protected byte[] data

The data payload this object carries. If it isn't an ack object, that buffer contains compressed data.

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type

protected byte type

This field can be one of the following type:

• ACK_TYPE for ack object,
• COMPR_TYPE for compressed object,
• UNCOMPR_TYPE for uncompressed object (actually nonsense).

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seqnum

protected long seqnum

The sequence number that distinguishes that object. If it's an ack object, the sequence number is the same as the compressed object that generated it, otherwise is automagically generated (using the method hashCode 55 applied to the data payload.

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ACK_TYPE

public static byte ACK_TYPE

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COMPR_TYPE

public static byte COMPR_TYPE

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UNCOMPR_TYPE

public static byte UNCOMPR_TYPE

Constructor Detail

ZObject

public ZObject(long seqnum)

Constructor used to build an ack object with a well-defined sequence number.

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ZObject

public ZObject(java.io.InputStream in)
        throws java.io.IOException,
               AckException

Constructor used to build an object by deserializing data coming from an input stream, tipically a socket input stream.

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ZObject

public ZObject(DatagramPacket packet)
        throws AckException,
               NoMagicException,
               java.io.IOException

Constructor used to build an object by deserializing data coming from the buffer contained in the passed datagram.

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ZObject

public ZObject(byte[] _data,
               byte type)
        throws java.io.IOException

Constructor used to build a generic ZObject instance.

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ZObject

public ZObject(byte[] _data)
        throws java.io.IOException

Constructor used to build a compressed object with a specific data payload.

Method Detail

create

protected void create(byte[] _data,
                      byte type)

This method is responsible for generic object creation and it's an utility method used by constructors.

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prepareData

public byte[] prepareData()
                   throws java.io.IOException

This method actually performs encoding on the internal object using a ByteArrayOutputStream as a container where internal fields get written into.

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getSeqNum

public long getSeqNum()

This method returns the carried sequence number.

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getData

public byte[] getData()

This method returns the carried data payload.

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serialize

protected static byte[] serialize(long num)

This method converts a passed long into a sequence of four bytes that can be written to an output stream.

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positivize

protected static long positivize(long x)

This method positivize the passed long using steps of value 256. This ensure the following relation always true: <result> mod 256==x mod 256

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deserialize

protected static long deserialize(byte[] buf)

This method decodes an array of four bytes into a long value.

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setData

public void setData(byte[] dat)
             throws java.io.IOException,
                    AckException

This method decodes the passed byte array trying to deserialize a ZObject instance.

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dump

public boolean dump(byte[] buf,
                    int len)

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setData

public void setData(java.io.InputStream in)
             throws java.io.IOException,
                    AckException

This method decodes data from the input stream trying to deserialize a ZObject instance.

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toString

public java.lang.String toString()

Description copied from class: java.lang.Object

Convert this Object to a human-readable String. There are no limits placed on how long this String should be or what it should contain. We suggest you make it as intuitive as possible to be able to place it into System.out.println() 55 and such.

It is typical, but not required, to ensure that this method never completes abruptly with a java.lang.RuntimeException.

This method will be called when performing string concatenation with this object. If the result is null, string concatenation will instead use "null".

The default implementation returns getClass().getName() + "@" + Integer.toHexString(hashCode()).

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SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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