一、在 .NET 中生成
1、直接用.NET Framework 提供的 Guid() 函数，此种方法使用非常广泛。GUID（全局统一标识符）是指在一台机器上生成的数字，它保证对在同一时空中的任何两台计算机都不会生成重复的 GUID 值（即保证所有机器都是唯一的）。关于GUID的介绍在此不作具体熬述，想深入了解可以自行查阅MSDN。代码如下：
代码如下:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
string _guid = GetGuid();
Console.WriteLine("唯一码：{0}\t长度为：{1}\n去掉连接符：{2}", _guid, _guid.Length, _guid.Replace("-", ""));
string uniqueIdString = GuidTo16String();
Console.WriteLine("唯一码：{0}\t长度为：{1}", uniqueIdString, uniqueIdString.Length);
long uniqueIdLong = GuidToLongID();
Console.WriteLine("唯一码：{0}\t长度为：{1}", uniqueIdLong, uniqueIdLong.ToString().Length);
}
/// <summary>
/// 由连字符分隔的32位数字
/// </summary>
/// <returns></returns>
private static string GetGuid()
{
System.Guid guid = new Guid();
guid = Guid.NewGuid();
return guid.ToString();
}
/// <summary>
/// 根据GUID获取16位的唯一字符串
/// </summary>
/// <param name=\"guid\"></param>
/// <returns></returns>
public static string GuidTo16String()
{
long i = 1;
foreach (byte b in Guid.NewGuid().ToByteArray())
i *= ((int)b + 1);
return string.Format("{0:x}", i - DateTime.Now.Ticks);
}
/// <summary>
/// 根据GUID获取19位的唯一数字序列
/// </summary>
/// <returns></returns>
public static long GuidToLongID()
{
byte[] buffer = Guid.NewGuid().ToByteArray();
return BitConverter.ToInt64(buffer, 0);
}
}
}
2、用 DateTime.Now.ToString("yyyyMMddHHmmssms") 和 .NET Framework 提供的 RNGCryptoServiceProvider() 结合生成，代码如下：
代码如下:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
string uniqueNum = GenerateOrderNumber();
Console.WriteLine("唯一码：{0}\t 长度为：{1}", uniqueNum, uniqueNum.Length);
//测试是否会生成重复
Console.WriteLine("时间+RNGCryptoServiceProvider()结合生成的唯一值，，如下：");
string _tempNum = string.Empty;
for (int i = 0; i < 1000; i++)
{
string uNum = GenerateOrderNumber();
Console.WriteLine(uNum);
if (string.Equals(uNum, _tempNum))
{
Console.WriteLine("上值存在重复，按Enter键继续");
Console.ReadKey();
}
//Sleep当前线程，是为了延时，从而不产生重复值。可以把它注释掉测试看
Thread.Sleep(300);
_tempNum = uNum;
}
}
/// <summary>
/// 唯一订单号生成
/// </summary>
/// <returns></returns>
public static string GenerateOrderNumber()
{
string strDateTimeNumber = DateTime.Now.ToString("yyyyMMddHHmmssms");
string strRandomResult = NextRandom(1000, 1).ToString();
return strDateTimeNumber + strRandomResult;
}
/// <summary>
/// 参考：msdn上的RNGCryptoServiceProvider例子
/// </summary>
/// <param></param>
/// <param></param>
/// <returns></returns>
private static int NextRandom(int numSeeds, int length)
{
// Create a byte array to hold the random value.
byte[] randomNumber = new byte[length];
// Create a new instance of the RNGCryptoServiceProvider.
System.Security.Cryptography.RNGCryptoServiceProvider rng = new System.Security.Cryptography.RNGCryptoServiceProvider();
// Fill the array with a random value.
rng.GetBytes(randomNumber);
// Convert the byte to an uint value to make the modulus operation easier.
uint randomResult = 0x0;
for (int i = 0; i < length; i++)
{
randomResult |= ((uint)randomNumber[i] << ((length - 1 - i) * 8));
}
return (int)(randomResult % numSeeds) + 1;
}
}
}
3、用 [0-9A-Z] + Guid.NewGuid() 结合生成特定位数的唯一字符串，代码如下：
代码如下:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
string uniqueText = GenerateUniqueText(8);
Console.WriteLine("唯一码：{0}\t 长度为：{1}", uniqueText, uniqueText.Length);
//测试是否会生成重复
Console.WriteLine("由[0-9A-Z] + NewGuid() 结合生成的唯一值，如下：");
IList<string> list = new List<string>();
for (int i = 1; i <= 1000; i++)
{
string _uT = GenerateUniqueText(8);
Console.WriteLine("{0}\t{1}", list.Count, _uT);
if (list.Contains(_uT))
{
Console.WriteLine("{0}值存在重复", _uT);
Console.ReadKey();
}
list.Add(_uT);
//if (i % 200 == 0)
//{
//Console.WriteLine("没有重复，按Enter键往下看");
//Console.ReadKey();
//}
}