生成唯一号：思路，根据yymmddhhmmss+自增长号+唯一服务器号( SystemNo)生成唯一码，总长度19，例如：1509281204550000101.
public class UniqueNumber
{ private static long num = 0;//流水号
private static object lockObj = new object();//锁
/// <summary>
/// 生成自增长码
/// </summary>
/// <returns></returns>
private static long GenerateUniqueNumber()
{
lock (lockObj)//加锁
{
num = num + 1;
num = (num == 100000 ? 1 : num); //如果大于10W则从零开始，由于一台服务器一秒内不太可能有10W并发，所以yymmddhhmmss+num是唯一号。yymmddhhmmss+num+SystemNo针对多台服务器也是唯一号。
}
return num;
}
/// <summary>
/// 获取唯一码
/// </summary>
/// <param name="SystemNo">系统号</param>
/// <returns>唯一码</returns>
public static long GetUniqueNumber(int SystemNo)
{
if (SystemNo > 99 || SystemNo < 1)
{
throw new Exception("系统号有误");
}
lock (lockObj)// 要使静态变量多并发下同步，需要两次加锁。
{
string time = DateTime.Now.ToString("yyMMddHHmmss");//12位;
return long.Parse(time + GenerateUniqueNumber().ToString().PadLeft(5, '0') + SystemNo.ToString().PadLeft(2, '0'));//19位
}
}
}
测试：
static void Main(string[] args)
{
for (int i = 1; i < 98; i++)//N个线程
{
Thread thread = new Thread(new ParameterizedThreadStart(Exe));
thread.Start(i);
}
}
public static void Exe(object sysNo)
{
for (int i = 0; i < 1000; i++)//M次循环执行
{
long v = UniqueNumber.GetUniqueNumber((int)sysNo);
DbHelperMySQL.ExecuteSql(" insert into abacus.guidtest (val) values ('" + v + "');");
}
}
mySQl脚本:
SELECT * FROM abacus.guidtest;
select count(id) from abacus.guidtest;
select val from abacus.guidtest
group by val
having count(val) >1;
truncate table abacus.guidtest;
CREATE TABLE `guidtest`
`id` int(11) NOT NULL AUTO_INCREMENT,
`val` bigint(20) NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `id_UNIQUE` (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;