randomsecquencecreator.java

来自「cwbbs 云网论坛源码」· Java 代码 · 共 69 行

package cn.js.fan.util;

import java.util.Random;
import java.util.Hashtable;


public class RandomSecquenceCreator {
    static Hashtable hash = new Hashtable();
    
    static Random rand = new Random(System.currentTimeMillis());
    static long lastRandTime = System.currentTimeMillis();

    public RandomSecquenceCreator() {
    }

    
    public static String getId() {
        
        if (System.currentTimeMillis()-lastRandTime>20000)
            hash.clear();
        Integer id = new Integer(0);
        synchronized (hash) {
            
            id = new Integer(rand.nextInt());
            while (hash.containsKey(id)) {
                id = new Integer(rand.nextInt());
            }
            
            String data = "";
            hash.put(id, data);
        }
        lastRandTime = System.currentTimeMillis();
        return System.currentTimeMillis() + "" + Math.abs(id.intValue());
    }

    
    public static String getId(int length) {
        
        if (System.currentTimeMillis()-lastRandTime>20000)
            hash.clear();
        Integer id = new Integer(0);
        String strId = "";
        synchronized (hash) {
            
            id = new Integer(rand.nextInt());
            if (length > 15)
                strId = System.currentTimeMillis() + "" + Math.abs(id.intValue());
            else
                strId = "" + Math.abs(id.intValue());
            if (strId.length() > length)
                strId = strId.substring(0, length);
            while (hash.containsKey(strId)) {
                id = new Integer(rand.nextInt());
                if (length > 15)
                    strId = System.currentTimeMillis() + "" + Math.abs(id.intValue());
                else
                    strId = "" + Math.abs(id.intValue());
                if (strId.length() > length)
                    strId = strId.substring(0, length);
            }
            
            String data = "";
            hash.put(strId, data);
        }
        lastRandTime = System.currentTimeMillis();
        return strId;
    }
}