idgenerator.java

来自「EasyDBO v0.4 是一个非常适合中小型软件数据库开发的数据持久层框架」· Java 代码 · 共 45 行

package com.easyjf.dbo;
import java.util.Random;

public class IdGenerator implements IIdGenerator {
	//private static IdGenerator idGenerator=null;	
	public IdGenerator()
	{		
	}
	/*
	public synchronized static IdGenerator getInstance()
	{		
			if(idGenerator==null)
			{
			idGenerator=new IdGenerator();	
			}			
			return idGenerator;
	}*/
	public synchronized Object generator(Class classType) {		
		return nextValue(classType,null);
	}
	public Object generator(Class classType,String column) {		
		return nextValue(classType,column);
	}
	
	private synchronized String nextValue(Class classType,String column)
	{	
		
		StringBuffer id=new StringBuffer(""+(new java.util.Date().getTime()));
		Random r=new Random(10);
		id.append(Math.abs(r.nextInt()));		
		if(!check(id.substring(0,16),classType,column))return nextValue(classType,column);
		else return id.substring(0,16);
		
	}
	private synchronized boolean check(String id,Class classType,String column)
	{
			boolean r=true;		
			EasyJDB db=EasyJDB.getInstance();			
			Object obj=db.get(classType,id);
			if(obj!=null)r=false;			
			return r;
	}

}