hashfunction.java

发布/订阅系统路由重配算法,可应用于ad hoc环境

/*
 * project: RebecaSim
 * package: broker
 * file:    HashFunction.java
 * 
 * version: 0.1
 * date:    10.05.2005
 * 
 * This software is part of the diploma thesis "Ein adaptives Brokernetz 
 * für Publish/Subscribe Systeme".
 */
package broker;

import java.util.*;

/**
 * This class implements a simple hash function based on java's own
 * pseudo random generator. To hash a value the random generator's seed
 * is set to a value dependent bit pattern. The pattern is determined
 * by value xor hashseed, where hashseed is the hash functions own seed.
 *
 * @version 10.05.2005
 * @author  parzy
 */
public class HashFunction {

	/**
	 * The used random generator.
	 */
	private static Random rand = new Random();
	
	/**
	 * The hash functions own seed.
	 */
	private long seed;
	
	/**
	 * Creates a hash function with the given seed.
	 * @param seed the hash function's seed.
	 */
	public HashFunction(long seed){
		this.seed = seed;
	}
	
	/**
	 * Hashs the value. 
	 * @param value the value to hash.
	 * @return the value's hash.
	 */
	public int hash(int value){
		rand.setSeed(seed ^ value);
		return rand.nextInt();
	}
}