生成若干位数的随机ID

写了如下工具类：

public class SystemUtil {
	public static String getRandomNumberByNum(int num) {
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < num; i++) {
			long randomNum = Math.round(Math.floor(Math.random() * 10.0D));
			sb.append(randomNum);
		}
		return sb.toString();
	}

	
}

public class Producer {
	public static String generateIdOfTen() {
		String randomNumber = SystemUtil.getRandomNumberByNum(10);
		long time = System.currentTimeMillis();
		return time + randomNumber;
	}
}

生成若干位数的随机ID

原文：http://blog.csdn.net/changhuiyuanh/article/details/19288173