anthill.types
Class SHADocumentId

java.lang.Object
  |
  +--anthill.util.SHADigest
        |
        +--anthill.types.SHADocumentId

All Implemented Interfaces:

Closeness, Comparable, Externalizable, Serializable

public class SHADocumentId

extends SHADigest

Probabilistic identifier for a document.

Version:

$Revision: 1.2 $

Author:

Alberto Montresor

See Also:

Serialized Form

Field Summary

protected int

length Length of the document

Fields inherited from class anthill.util.SHADigest

digest, DIGEST_SIZE, DIGEST_TYPE, hashcode, random, RANDOM_TYPE, rdigest

Constructor Summary

SHADocumentId()
Default constructor for externalization.

Method Summary

protected void	computeHash() Computes the hash code for this SHADocumentId.
protected void	computeSHADocumentId(String urlPath) Computes a fake SHADocumentId based on the path component of the specified URL.
protected void	computeSHADocumentId(URL url) Reads data from the specified URL and computes the length and digest components that comprise the SHADocumentId.
boolean	equals(Object obj) Check whether this SHADocumentId is equal to the specified object.
int	getLength() Returns the length component of the SHADocumentId.
void	readExternal(ObjectInput in) Marshals this SHADocumentId to the specified output stream.
String	toString() Returns a string representation of the object.
void	writeExternal(ObjectOutput out) Marshals this SHADocumentId to the specified output stream.

Methods inherited from class anthill.util.SHADigest

compareTo, compareTo, computeDigest, computeRandomSHA, getBytes, hashCode, initRandom, isCloser

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

length

protected int length

Length of the document

Constructor Detail

SHADocumentId

public SHADocumentId()

Default constructor for externalization.

Method Detail

computeSHADocumentId

protected void computeSHADocumentId(URL url)
                             throws IOException

Reads data from the specified URL and computes the length and digest components that comprise the SHADocumentId.

Parameters:

url - the URL from which to read the data needed to compute the SHADocumentId.

Throws:

IOException - if an error occurs

computeSHADocumentId

protected void computeSHADocumentId(String urlPath)

Computes a fake SHADocumentId based on the path component of the specified URL. This is useful for simulation purposes only.

Parameters:

urlPath - the path component of a URL.

computeHash

protected void computeHash()

Computes the hash code for this SHADocumentId.

Note that we wish to avoid computing the hashcode of a big integer every time, so therefore we compute the hashcode prior to its use and store it for future calls to the hashcode method.

Overrides:

computeHash in class SHADigest

getLength

public int getLength()

Returns the length component of the SHADocumentId.

Returns:

the length component of the SHADocumentId.

equals

public boolean equals(Object obj)

Check whether this SHADocumentId is equal to the specified object.

Overrides:

equals in class SHADigest

Parameters:

obj - the reference object with which to compare.

Returns:

true if this object is the same as the obj argument; false otherwise.

toString

public String toString()

Returns a string representation of the object.

Overrides:

toString in class SHADigest

readExternal

public void readExternal(ObjectInput in)
                  throws IOException

Marshals this SHADocumentId to the specified output stream.

Specified by:

readExternal in interface Externalizable

Overrides:

readExternal in class SHADigest

Parameters:

in - an ObjectInput stream object

Throws:

IOException - if an error occurs

writeExternal

public void writeExternal(ObjectOutput out)
                   throws IOException

Marshals this SHADocumentId to the specified output stream.

Specified by:

writeExternal in interface Externalizable

Overrides:

writeExternal in class SHADigest

Parameters:

out - an ObjectOutput stream object

Throws:

IOException - if an error occurs