keygenerator.java

java与模式 一书的源码

package com.javapatterns.keygen.ver4;

import java.util.HashMap;

public class KeyGenerator
{
    /**
     * @label creates 
     */
	private static KeyGenerator keygen =
        new KeyGenerator();

    private static final int POOL_SIZE = 20;

    private HashMap keyList = new HashMap(10);

    /** @link dependency */
    /*# KeyInfo lnkKeyInfo; */

    private KeyGenerator()
    {
    }

    public static KeyGenerator getInstance()
    {
    	return keygen;
    }

    public int getNextKey(String keyName)
    {
        KeyInfo keyinfo ;

		if ( keyList.containsKey(keyName) )
        {
			keyinfo = (KeyInfo) keyList.get(keyName);
            System.out.println("key found");
        }
        else
        {
			keyinfo = new KeyInfo(POOL_SIZE, keyName);
            keyList.put(keyName, keyinfo);

            System.out.println("new key created");
        }
        return keyinfo.getNextKey();
    }
}