C#生成唯一值的方法汇总
生成唯一值的方法很多，下面就不同环境下生成的唯一标识方法一一介绍，作为工作中的一次总结，有兴趣的可以自行测试：
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：
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：
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 name="numseeds"></param>
/// <param name="length"></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：
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();
//}
}
list.clear();
}
/// <summary>
/// 生成特定位数的唯一字符串
/// </summary>
/// <param name="num">特定位数</param>
/// <returns></returns>
public static string generateuniquetext(int num)
{
string randomresult = string.empty;
string readystr = "0123456789abcdefghijklmnopqrstuvwxyz";
char[] rtn = new char[num];
guid gid = guid.newguid();
var ba = gid.tobytearray();
for (var i = 0; i < num; i++)
{
rtn[i] = readystr[((ba[i] + ba[num + i]) % 35)];
}
foreach (char r in rtn)
{
randomresult += r;
}
return randomresult;
}
}
}
4、用单例模式实现，由[0-9a-z]组合生成的唯一值，此文不讨论单例模式的多种实现方式与性能问题，随便弄一种方式实现，代码如下：
demo结构如图：
program.cs 程序：
using system;
using system.collections.generic;
using system.linq;
using system.text;
using system.collections;
using system.xml;
namespace consoleapplication4
{
class program
{
static void main(string[] args)
{
createid createid = createid.getinstance();
//测试是否会生成重复
console.writeline("单例模式实现，由[0-9a-z]组合生成的唯一值，如下：");
ilist<string> list = new list<string>();
for (int i = 1; i <= 1000000000; i++)
{
string struniquenum = createid.createuniqueid();
console.writeline("{0}\t{1}", list.count, struniquenum);
if (list.contains(struniquenum))
{
console.writeline("{0}值存在重复", struniquenum);
console.readkey();
}
list.add(struniquenum);
if (i % 200 == 0)
{
console.writeline("没有重复，按enter键往下看");
console.readkey();
}
}
list.clear();
}
}
/// <summary>
/// 单例模式实现
/// 唯一值由[0-9a-z]组合而成，且生成的每个id不能重复
/// </summary>
public class createid
{
private static createid _instance;
private static readonly object syncroot = new object();
private ehashtable hashtable = new ehashtable();
private string _strxmlurl = string.empty;
private createid()
{
hashtable.add("0", "0");
hashtable.add("1", "1");
hashtable.add("2", "2");
hashtable.add("3", "3");
hashtable.add("4", "4");
hashtable.add("5", "5");
hashtable.add("6", "6");
hashtable.add("7", "7");
hashtable.add("8", "8");
hashtable.add("9", "9");
hashtable.add("10", "a");
hashtable.add("11", "b");
hashtable.add("12", "c");
hashtable.add("13", "d");
hashtable.add("14", "e");
hashtable.add("15", "f");
hashtable.add("16", "g");
hashtable.add("17", "h");
hashtable.add("18", "i");
hashtable.add("19", "j");
hashtable.add("20", "k");
hashtable.add("21", "l");
hashtable.add("22", "m");
hashtable.add("23", "n");
hashtable.add("24", "o");
hashtable.add("25", "p");
hashtable.add("26", "q");
hashtable.add("27", "r");
hashtable.add("28", "s");
hashtable.add("29", "t");
hashtable.add("30", "u");
hashtable.add("31", "v");
hashtable.add("32", "w");
hashtable.add("33", "x");
hashtable.add("34", "y");
hashtable.add("35", "z");
_strxmlurl = system.io.path.getfullpath(@"..\..\") + "xmls\\record.xml";
}
public static createid getinstance()
{
if (_instance == null)
{
lock (syncroot)
{
if (_instance == null)
{
_instance = new createid();
}
}
}
return _instance;
}
/// <summary>
/// 创建uniqueid
/// </summary>
/// <returns>uniqueid</returns>
public string createuniqueid()
{
long _uniqueid = getguidfromxml();
return convert10to36(_uniqueid);
}
/// <summary>
/// 获取uniqueid总记录，即获取得到的这个id是第几个id
/// 更新uniqueid使用的个数，用于下次使用
/// </summary>
/// <returns></returns>
private long getguidfromxml()
{
long record = 0;
xmldocument xmldoc = new xmldocument();
xmldoc.load(_strxmlurl);
xmlelement rootnode = xmldoc.documentelement;
//此次的个数值
record = convert.toint64(rootnode["record"].innertext);
//此次的个数值+1 == 下次的个数值
rootnode["record"].innertext = convert.tostring(record + 1);
xmldoc.save(_strxmlurl);
return record;
}
/// <summary>
/// 10进制转36进制
/// </summary>
/// <param name="intnum10">10进制数</param>
/// <returns></returns>
private string convert10to36(long intnum10)
{
string strnum36 = string.empty;
long result = intnum10 / 36;
long remain = intnum10 % 36;
if (hashtable.containskey(remain.tostring()))
strnum36 = hashtable[remain.tostring()].tostring() + strnum36;
intnum10 = result;
while (intnum10 / 36 != 0)
{
result = intnum10 / 36;
remain = intnum10 % 36;
if (hashtable.containskey(remain.tostring()))
strnum36 = hashtable[remain.tostring()].tostring() + strnum36;
intnum10 = result;
}
if (intnum10 > 0 && intnum10 < 36)
{
if (hashtable.containskey(intnum10.tostring()))
strnum36 = hashtable[intnum10.tostring()].tostring() + strnum36;
}
return strnum36;
}
}
/// <summary>
/// summary description for ehashtable
/// </summary>
public class ehashtable : hashtable
{
private arraylist list = new arraylist();
public override void add(object key, object value)
{
base.add(key, value);
list.add(key);
}
public override void clear()
{
base.clear();
list.clear();
}
public override void remove(object key)
{
base.remove(key);
list.remove(key);
}
public override icollection keys
{
get
{
return list;
}
}
}
}
xml：
<?xml version="1.0" encoding="utf-8"?>
<root>
<record id="record">1</record>
</root>
二、在js中生成guid，类似.net中的 guid.newguid()，代码如下：
function newguid() { //方法一：
var guid = "";
var n = (((1 + math.random()) * 0x10000) | 0).tostring(16).substring(1);
for (var i = 1; i <= 8; i++) {
guid += n;
}
return guid;
}
function newguid() { //方法二：
var guid = "";
for (var i = 1; i <= 32; i++) {
var n = math.floor(math.random() * 16.0).tostring(16);
guid += n;
if ((i == 8) || (i == 12) || (i == 16) || (i == 20))
guid += "-";
}
return guid;
}
三、在sql存储过程生成guid，代码如下：
-- =============================================
-- author: jben
-- create date: 2012-06-05
-- description: 生成唯一标识id，公共存储过程，可设置在别的存储过程调用此存储过程传不同的前缀
-- =============================================
alter procedure [dbo].[pro_createguid]
@prefix nvarchar(10),
@outputv_guid nvarchar(40) output
as
begin
-- set nocount on added to prevent extra result sets from
-- interfering with select statements.
set nocount on;
-- insert statements for procedure here
set @outputv_guid = @prefix + replace(cast(newid() as varchar(36)),'-','')
end