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：
https://www.cnblogs.com/xinweichen/p/4287640.html
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：
1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Text;
5 namespace ConsoleApplication1
6 {
7 class Program
8 {
9 static void Main(string[] args)
10 {
11 string _guid = GetGuid();
12 Console.WriteLine("唯一码：{0} 长度为：{1}
去掉连接符：{2}", _guid, _guid.Length, _guid.Replace("-", ""));
13 string uniqueIdString = GuidTo16String();
14 Console.WriteLine("唯一码：{0} 长度为：{1}", uniqueIdString, uniqueIdString.Length);
15 long uniqueIdLong = GuidToLongID();
16 Console.WriteLine("唯一码：{0} 长度为：{1}", uniqueIdLong, uniqueIdLong.ToString().Length);
17 }
18 /// <summary>
19 /// 由连字符分隔的32位数字
20 /// </summary>
21 /// <returns></returns>
22 private static string GetGuid()
23 {
24 System.Guid guid = new Guid();
25 guid = Guid.NewGuid();
26 return guid.ToString();
27 }
28 /// <summary>
29 /// 根据GUID获取16位的唯一字符串
30 /// </summary>
31 /// <param name="guid"></param>
32 /// <returns></returns>
33 public static string GuidTo16String()
34 {
35 long i = 1;
36 foreach (byte b in Guid.NewGuid().ToByteArray())
37 i *= ((int)b + 1);
38 return string.Format("{0:x}", i - DateTime.Now.Ticks);
39 }
40 /// <summary>
41 /// 根据GUID获取19位的唯一数字序列
42 /// </summary>
43 /// <returns></returns>
44 public static long GuidToLongID()
45 {
46 byte[] buffer = Guid.NewGuid().ToByteArray();
47 return BitConverter.ToInt64(buffer, 0);
48 }
49 }
50 }
2、用 DateTime.Now.ToString("yyyyMMddHHmmssms") 和 .NET Framework 提供的 RNGCryptoServiceProvider() 结合生成，代码如下：
1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Text;
5 using System.Threading;
6 namespace ConsoleApplication1
7 {
8 class Program
9 {
10 static void Main(string[] args)
11 {
12 string uniqueNum = GenerateOrderNumber();
13 Console.WriteLine("唯一码：{0} 长度为：{1}", uniqueNum, uniqueNum.Length);
14 //测试是否会生成重复
15 Console.WriteLine("时间+RNGCryptoServiceProvider()结合生成的唯一值，如下：");
16 string _tempNum = string.Empty;
17 for (int i = 0; i < 1000; i++)
18 {
19 string uNum = GenerateOrderNumber();
20 Console.WriteLine(uNum);
21 if (string.Equals(uNum, _tempNum))
22 {
23 Console.WriteLine("上值存在重复，按Enter键继续");
24 Console.ReadKey();
25 }
26 //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
27 Thread.Sleep(300);
28 _tempNum = uNum;
29 }
30 }
31 /// <summary>
32 /// 唯一订单号生成
33 /// </summary>
34 /// <returns></returns>
35 public static string GenerateOrderNumber()
36 {
37 string strDateTimeNumber = DateTime.Now.ToString("yyyyMMddHHmmssms");
38 string strRandomResult = NextRandom(1000, 1).ToString();
39 return strDateTimeNumber + strRandomResult;
40 }
41 /// <summary>
42 /// 参考：msdn上的RNGCryptoServiceProvider例子
43 /// </summary>
44 /// <param name="numSeeds"></param>
45 /// <param name="length"></param>
46 /// <returns></returns>
47 private static int NextRandom(int numSeeds, int length)
48 {
49 // Create a byte array to hold the random value.
50 byte[] randomNumber = new byte[length];
51 // Create a new instance of the RNGCryptoServiceProvider.
52 System.Security.Cryptography.RNGCryptoServiceProvider rng = new System.Security.Cryptography.RNGCryptoServiceProvider();
53 // Fill the array with a random value.
54 rng.GetBytes(randomNumber);
55 // Convert the byte to an uint value to make the modulus operation easier.
56 uint randomResult = 0x0;
57 for (int i = 0; i < length; i++)
58 {
59 randomResult |= ((uint)randomNumber[i] << ((length - 1 - i) * 8));
60 }
61 return (int)(randomResult % numSeeds) + 1;
62 }
63 }
64 }
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：
1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Text;
5 namespace ConsoleApplication1
6 {
7 class Program
8 {
9 static void Main(string[] args)
10 {
11 string uniqueText = GenerateUniqueText(8);
12 Console.WriteLine("唯一码：{0} 长度为：{1}", uniqueText, uniqueText.Length);
13 //测试是否会生成重复
14 Console.WriteLine("由[0-9A-Z] + NewGuid() 结合生成的唯一值，如下：");
15 IList<string> list = new List<string>();
16 for (int i = 1; i <= 1000; i++)
17 {
18 string _uT = GenerateUniqueText(8);
19 Console.WriteLine("{0} {1}", list.Count, _uT);
20 if (list.Contains(_uT))
21 {
22 Console.WriteLine("{0}值存在重复", _uT);
23 Console.ReadKey();
24 }
25 list.Add(_uT);
26 //if (i % 200 == 0)
27 //{
28 //Console.WriteLine("没有重复，按Enter键往下看");
29 //Console.ReadKey();
30 //}
31 }
32 list.Clear();
33 }
34
35 /// <summary>
36 /// 生成特定位数的唯一字符串
37 /// </summary>
38 /// <param name="num">特定位数</param>
39 /// <returns></returns>
40 public static string GenerateUniqueText(int num)
41 {
42 string randomResult = string.Empty;
43 string readyStr = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
44 char[] rtn = new char[num];
45 Guid gid = Guid.NewGuid();
46 var ba = gid.ToByteArray();
47 for (var i = 0; i < num; i++)
48 {
49 rtn[i] = readyStr[((ba[i] + ba[num + i]) % 35)];
50 }
51 foreach (char r in rtn)
52 {
53 randomResult += r;
54 }
55 return randomResult;
56 }
57 }
58 }
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：
1 using System;
2 using System.Collections.Generic;
3 using System.Linq;
4 using System.Text;
5 using System.Collections;
6 using System.Xml;
7 namespace ConsoleApplication4
8 {
9 class Program
10 {
11 static void Main(string[] args)
12 {
13 CreateID createID = CreateID.GetInstance();
14 //测试是否会生成重复
15 Console.WriteLine("单例模式实现，由[0-9a-z]组合生成的唯一值，如下：");
16 IList<string> list = new List<string>();
17 for (int i = 1; i <= 1000000000; i++)
18 {
19 string strUniqueNum = createID.CreateUniqueID();
20 Console.WriteLine("{0} {1}", list.Count, strUniqueNum);
21 if (list.Contains(strUniqueNum))
22 {
23 Console.WriteLine("{0}值存在重复", strUniqueNum);
24 Console.ReadKey();
25 }
26 list.Add(strUniqueNum);
27 if (i % 200 == 0)
28 {
29 Console.WriteLine("没有重复，按Enter键往下看");
30 Console.ReadKey();
31 }
32 }
33 list.Clear();
34 }
35 }
36 /// <summary>
37 /// 单例模式实现
38 /// 唯一值由[0-9a-z]组合而成，且生成的每个ID不能重复
39 /// </summary>
40 public class CreateID
41 {
42 private static CreateID _instance;
43 private static readonly object syncRoot = new object();
44 private EHashtable hashtable = new EHashtable();
45 private string _strXMLURL = string.Empty;
46 private CreateID()
47 {
48 hashtable.Add("0", "0");
49 hashtable.Add("1", "1");
50 hashtable.Add("2", "2");
51 hashtable.Add("3", "3");
52 hashtable.Add("4", "4");
53 hashtable.Add("5", "5");
54 hashtable.Add("6", "6");
55 hashtable.Add("7", "7");
56 hashtable.Add("8", "8");
57 hashtable.Add("9", "9");
58 hashtable.Add("10", "a");
59 hashtable.Add("11", "b");
60 hashtable.Add("12", "c");
61 hashtable.Add("13", "d");
62 hashtable.Add("14", "e");
63 hashtable.Add("15", "f");
64 hashtable.Add("16", "g");
65 hashtable.Add("17", "h");
66 hashtable.Add("18", "i");
67 hashtable.Add("19", "j");
68 hashtable.Add("20", "k");
69 hashtable.Add("21", "l");
70 hashtable.Add("22", "m");
71 hashtable.Add("23", "n");
72 hashtable.Add("24", "o");
73 hashtable.Add("25", "p");
74 hashtable.Add("26", "q");
75 hashtable.Add("27", "r");
76 hashtable.Add("28", "s");
77 hashtable.Add("29", "t");
78 hashtable.Add("30", "u");
79 hashtable.Add("31", "v");
80 hashtable.Add("32", "w");
81 hashtable.Add("33", "x");
82 hashtable.Add("34", "y");
83 hashtable.Add("35", "z");
84 _strXMLURL = System.IO.Path.GetFullPath(@"....") + "XMLs\record.xml";
85
86 }
87 public static CreateID GetInstance()
88 {
89 if (_instance == null)
90 {
91 lock (syncRoot)
92 {
93 if (_instance == null)
94 {
95 _instance = new CreateID();
96 }
97 }
98 }
99 return _instance;
100 }
101 /// <summary>
102 /// 创建UniqueID
103 /// </summary>
104 /// <returns>UniqueID</returns>
105 public string CreateUniqueID()
106 {
107 long _uniqueid = GetGuidFromXml();
108 return Convert10To36(_uniqueid);
109 }
110 /// <summary>
111 /// 获取UniqueID总记录，即获取得到的这个ID是第几个ID
112 /// 更新UniqueID使用的个数，用于下次使用
113 /// </summary>
114 /// <returns></returns>
115 private long GetGuidFromXml()
116 {
117 long record = 0;
118 XmlDocument xmldoc = new XmlDocument();
119 xmldoc.Load(_strXMLURL);
120 XmlElement rootNode = xmldoc.DocumentElement;
121 //此次的个数值
122 record = Convert.ToInt64(rootNode["record"].InnerText);
123 //此次的个数值+1 == 下次的个数值
124 rootNode["record"].InnerText = Convert.ToString(record + 1);
125 xmldoc.Save(_strXMLURL);
126 return record;
127 }
128 /// <summary>
129 /// 10进制转36进制
130 /// </summary>
131 /// <param name="intNum10">10进制数</param>
132 /// <returns></returns>
133 private string Convert10To36(long intNum10)
134 {
135 string strNum36 = string.Empty;
136 long result = intNum10 / 36;
137 long remain = intNum10 % 36;
138 if (hashtable.ContainsKey(remain.ToString()))
139 strNum36 = hashtable[remain.ToString()].ToString() + strNum36;
140 intNum10 = result;
141 while (intNum10 / 36 != 0)
142 {
143 result = intNum10 / 36;
144 remain = intNum10 % 36;
145 if (hashtable.ContainsKey(remain.ToString()))
146 strNum36 = hashtable[remain.ToString()].ToString() + strNum36;
147 intNum10 = result;
148 }
149 if (intNum10 > 0 && intNum10 < 36)
150 {
151 if (hashtable.ContainsKey(intNum10.ToString()))
152 strNum36 = hashtable[intNum10.ToString()].ToString() + strNum36;
153 }
154 return strNum36;
155 }
156 }
157 /// <summary>
158 /// Summary description for EHashTable
159 /// </summary>
160 public class EHashtable : Hashtable
161 {
162 private ArrayList list = new ArrayList();
163 public override void Add(object key, object value)
164 {
165 base.Add(key, value);
166 list.Add(key);
167 }
168 public override void Clear()
169 {
170 base.Clear();
171 list.Clear();
172 }
173 public override void Remove(object key)
174 {
175 base.Remove(key);
176 list.Remove(key);
177 }
178 public override ICollection Keys
179 {
180 get
181 {
182 return list;
183 }
184 }
185 }
186 }
XML：
1 <?xml version="1.0" encoding="utf-8"?> 2 <root> 3 <record id="record">1</record> 4 </root>
二、在JS中生成GUID，类似.NET中的 Guid.NewGuid()，代码如下：
1 function newGuid() { //方法一：
2 var guid = "";
3 var n = (((1 + Math.random()) * 0x10000) | 0).toString(16).substring(1);
4 for (var i = 1; i <= 8; i++) {
5 guid += n;
6 }
7 return guid;
8 }
9 function newGuid() { //方法二：
10 var guid = "";
11 for (var i = 1; i <= 32; i++) {
12 var n = Math.floor(Math.random() * 16.0).toString(16);
13 guid += n;
14 if ((i == 8) || (i == 12) || (i == 16) || (i == 20))
15 guid += "-";
16 }
17 return guid;
18 }
三、在SQL存储过程生成GUID，代码如下：
1 -- ============================================= 2 -- Author: JBen 3 -- Create date: 2012-06-05 4 -- 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 5 -- ============================================= 6 ALTER PROCEDURE [dbo].[pro_CreateGuid] 7 @Prefix NVARCHAR(10), 8 @outputV_guid NVARCHAR(40) OUTPUT 9 AS 10 BEGIN 11 -- SET NOCOUNT ON added to prevent extra result sets from 12 -- interfering with SELECT statements. 13 SET NOCOUNT ON; 14 -- Insert statements for procedure here 15 SET @outputV_guid = @Prefix + REPLACE(CAST(NEWID() AS VARCHAR(36)),'-','') 16 END