生成唯一文件名不同方法

原创

jack2022 2022-09-29 11:18:22 博主文章分类：C# ©著作权

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生成唯一文件名不同方法

测试一

private void TestUnid()
{
    Parallel.For(1, 100, (i) =>
    {
        var fileName = DateTime.Now.ToString("yyyyMMddHHmmss");
        Random rnd = new Random();
        Console.WriteLine("fileName=" + fileName + rnd.Next(1000, 100000));
    });
}

输出：

fileName=2016102614594469808

...重复的

fileName=201610261459446330

...重复的

fileName=2016102614594411511

结论：可以看出有大量重复的文件名，原因是在并行时，Random用的默认种子是一样的，所以得到的随机数重复，

测试二

private static int iCount;

private void TestUnid()
{
  Parallel.For(1, 100, (i) =>
  {
    var fileName = DateTime.Now.ToString("yyyyMMddHHmmss");
    Random rnd = new Random();
    Interlocked.Increment(ref iCount);
    Console.WriteLine("fileName=" + fileName + rnd.Next(10, 10000)+"_"+iCount.ToString());
  });
}

输出：

fileName=201610261502447236_1

fileName=201610261502447236_3

fileName=201610261502447236_5

fileName=201610261502447236_6

fileName=201610261502447236_8

fileName=201610261502447236_9

fileName=201610261502447236_10

fileName=201610261502447236_11

fileName=201610261502447236_12

fileName=201610261502447236_13

fileName=201610261502447236_14

fileName=201610261502447236_15

fileName=201610261502447236_16

fileName=201610261502447236_17

fileName=201610261502447236_4

fileName=201610261502447236_19

fileName=201610261502447236_18

fileName=201610261502447236_21

fileName=201610261502447236_22

fileName=201610261502447236_23

fileName=201610261502447236_24

fileName=201610261502447236_25

fileName=201610261502447236_26

fileName=201610261502447236_27

fileName=201610261502447236_28

fileName=201610261502447236_29

fileName=201610261502447236_2

fileName=201610261502447236_31

fileName=201610261502447236_7

fileName=201610261502447236_33

fileName=201610261502447236_34

fileName=201610261502447236_35

fileName=201610261502447236_36

fileName=201610261502447236_20

fileName=201610261502447236_30

fileName=201610261502447236_32

fileName=201610261502447236_37

fileName=201610261502447236_41

fileName=201610261502447236_43

fileName=201610261502447236_44

fileName=201610261502447236_45

fileName=201610261502447236_46

fileName=201610261502447236_47

fileName=201610261502447236_48

fileName=201610261502447236_49

fileName=201610261502447236_50

fileName=201610261502447236_51

fileName=201610261502447236_42

fileName=201610261502447236_53

fileName=201610261502447236_54

fileName=201610261502447236_55

fileName=201610261502447236_56

fileName=201610261502447236_57

fileName=201610261502447236_58

fileName=201610261502447236_59

fileName=201610261502447236_60

fileName=201610261502447236_61

fileName=201610261502447236_62

fileName=201610261502447236_63

fileName=201610261502447236_64

fileName=201610261502447236_65

fileName=201610261502447236_39

fileName=201610261502447236_66

fileName=201610261502447236_40

fileName=201610261502447236_68

fileName=201610261502447236_38

fileName=201610261502447236_67

fileName=201610261502447236_69

fileName=201610261502447236_52

fileName=201610261502447759_73

fileName=201610261502447759_74

fileName=201610261502447759_75

fileName=201610261502447759_76

fileName=201610261502447759_77

fileName=201610261502447759_78

fileName=201610261502447759_79

fileName=201610261502447759_80

fileName=201610261502447759_81

fileName=201610261502447759_70

fileName=201610261502447759_82

fileName=201610261502447759_84

fileName=201610261502447759_85

fileName=201610261502447759_86

fileName=201610261502447759_87

fileName=201610261502447759_83

fileName=201610261502447759_71

fileName=201610261502447759_88

fileName=201610261502447759_72

fileName=201610261502447759_90

fileName=201610261502447759_91

fileName=201610261502447759_92

fileName=201610261502447759_93

fileName=201610261502447759_94

fileName=201610261502447759_89

fileName=201610261502447759_95

fileName=201610261502447759_96

fileName=201610261502447759_97

fileName=201610261502453063_98

fileName=201610261502453063_99

结论：可以看出没有重复的，但在这里随机数也还是没用，不重复是靠iCount来控制的

测试三

private void TestUnid()
{
  Parallel.For(1, 100, (i) =>
  {
    var fileName = DateTime.Now.ToString("yyyyMMddHHmmss");


    Random rnd = new Random(Guid.NewGuid().GetHashCode());
    Console.WriteLine("fileName=" + fileName + rnd.Next(10, 1000000));
  });
}

输出：

fileName=20161026151027973826

fileName=20161026151027179385

fileName=20161026151027445591

fileName=20161026151027847317

fileName=20161026151027606114

fileName=20161026151027929078

fileName=20161026151027304060

fileName=20161026151027690171

fileName=20161026151027611574

fileName=20161026151027479382

fileName=20161026151027721579

fileName=2016102615102738259

fileName=2016102615102734888

fileName=20161026151027315651

fileName=20161026151027724837

fileName=20161026151027547173

fileName=20161026151027314361

fileName=20161026151027235100

fileName=20161026151027463807

fileName=20161026151027912844

fileName=20161026151027260381

fileName=20161026151027984721

fileName=20161026151027293500

fileName=20161026151027123672

fileName=20161026151027597298

fileName=20161026151027885499

fileName=20161026151027408799

fileName=20161026151027196271

fileName=20161026151027472364

fileName=20161026151027844070

fileName=20161026151027789116

fileName=20161026151027643316

fileName=20161026151027502302

fileName=20161026151027448703

fileName=2016102615102751061

fileName=20161026151027151289

fileName=20161026151027366014

fileName=20161026151027517970

fileName=20161026151027277171

fileName=20161026151027861437

fileName=20161026151027180729

fileName=20161026151027910238

fileName=20161026151027864665

fileName=20161026151027529615

fileName=20161026151027421393

fileName=20161026151027225208

fileName=20161026151027118632

fileName=20161026151027453933

fileName=20161026151027781073

fileName=20161026151027435784

fileName=20161026151027259237

fileName=20161026151027600569

fileName=20161026151027521430

fileName=20161026151027237649

fileName=20161026151027933160

fileName=20161026151027396719

fileName=20161026151027685772

fileName=20161026151027701230

fileName=20161026151027400333

fileName=20161026151027410161

fileName=20161026151027788633

fileName=20161026151027936531

fileName=20161026151027522519

fileName=20161026151027849716

fileName=20161026151027590020

fileName=20161026151027555132

fileName=20161026151027259429

fileName=20161026151027567186

fileName=20161026151027390216

fileName=20161026151027614342

fileName=2016102615102854752

fileName=20161026151028173374

fileName=20161026151028991435

fileName=2016102615102894246

fileName=20161026151028497667

fileName=20161026151028365669

fileName=20161026151028808273

fileName=20161026151028568480

fileName=20161026151028686578

fileName=20161026151028627480

fileName=20161026151028248219

fileName=20161026151028691944

fileName=201610261510284772

fileName=20161026151028346370

fileName=20161026151028817242

fileName=20161026151028340723

fileName=20161026151028236019

fileName=20161026151028638904

fileName=20161026151028248779

fileName=20161026151028123635

fileName=20161026151028344443

fileName=20161026151028699403

fileName=20161026151028349303

fileName=20161026151028118220

fileName=20161026151028232106

fileName=20161026151028185281

fileName=2016102615102891660

fileName=20161026151028933221

fileName=20161026151028167604

结论：这里面应该也是没有重复的，但有重复的可能，因为虽然Random的种子每次不一样了，但生成随机数还是有可能会有重复，但概率比较小了，

测试四

private static int iCount;

private void TestUnid()
{
  Parallel.For(1, 100, (i) =>
  {
    var fileName = DateTime.Now.ToString("yyyyMMddHHmmss");
    Interlocked.Increment(ref iCount);
    Random rnd = new Random(Guid.NewGuid().GetHashCode());
    Console.WriteLine("fileName=" + fileName + iCount.ToString().PadRight(4,'0')+rnd.Next(1, 10000).ToString().PadLeft(4,'0'));
  });
}

输出：

fileName=2016102615421634001080

fileName=2016102615421633007073

fileName=2016102615421635000421

fileName=2016102615421636006721

fileName=2016102615421627005785

fileName=2016102615421638000321

fileName=2016102615421642003512

fileName=2016102615421641005752

fileName=2016102615421643008674

fileName=2016102615421644004218

fileName=2016102615421645008183

fileName=2016102615421646003962

fileName=2016102615421647000283

fileName=2016102615421648003970

fileName=2016102615421649005367

fileName=2016102615421651004208

fileName=2016102615421650001274

fileName=2016102615421652008767

fileName=2016102615421653000678

fileName=2016102615421654007918

fileName=2016102615421655002593

fileName=2016102615421656002064

fileName=2016102615421657009178

fileName=2016102615421658005146

fileName=2016102615421659006539

fileName=2016102615421660003764

fileName=2016102615421661008740

fileName=2016102615421640002590

fileName=2016102615421663000390

fileName=2016102615421664004351

fileName=2016102615421665000917

fileName=2016102615421666005014

fileName=2016102615421637000092

fileName=2016102615421639009017

fileName=2016102615421662001313

fileName=2016102615421667004809

fileName=2016102615421672006933

fileName=2016102615421673007296

fileName=2016102615421674009097

fileName=2016102615421675002749

fileName=2016102615421676006875

fileName=2016102615421677008682

fileName=2016102615421678005366

fileName=2016102615421669005274

fileName=2016102615421670002655

fileName=2016102615421679001878

fileName=2016102615421680004663

fileName=2016102615421681000694

fileName=2016102615421682007521

fileName=2016102615421683001165

fileName=2016102615421684007344

fileName=2016102615421685008041

fileName=2016102615421668002134

fileName=2016102615421686002166

fileName=2016102615421671003766

fileName=2016102615421687001968

fileName=2016102615421688007910

fileName=2016102615421689001718

fileName=2016102615421690003355

fileName=2016102615421691007049

fileName=2016102615421692006476

fileName=2016102615421693007589

fileName=2016102615421694003435

fileName=2016102615421695007512

fileName=2016102615421696006017

fileName=2016102615421697008858

fileName=2016102615421698007807

fileName=2016102615421699001709

结论：这个是没有重复的，生成的随机数种子也不同，而且带上iCount保证了唯一。

测试五

private void TestUnid()
{
  Parallel.For(1, 100, (i) =>
  {
    //不用ToString("N"),默认的是"D",里面带"-"
    var fileName = Guid.NewGuid().ToString("N");
    Console.WriteLine("fileName=" + fileName);
  });
}

输出：

fileName=48f5445240ab4e16b9243f833606c765

fileName=3001bccb4ecc4672a1492bf7ddb7b6aa

fileName=2a9091388671447b82dc38a8503d429e

fileName=3399220040c04d319774ed1891eddb2f

fileName=9716c75fd8a74ea38833b7fb126c32a2

fileName=e1062e22a2d4449395e39f86149bbfe8

fileName=8ab0e5fef7df44c29ee9a79a4f139630

fileName=e022a9af93b3451c9bf6fceb7e4a2c0b

fileName=4edfb58d071043dca5d574508696ed4a

fileName=a8b05d2ef92c422a8ebb128d0102af4d

fileName=5382d16c9eb140d192c7d083b05e19a9

fileName=14bde8b6f3cc42b2b3331c9c61a5d3f6

fileName=80f6848bbb224947a2b2326039f91050

fileName=dd3c8791bbbb4f17ba0910f67af857d6

fileName=35f348299803439b9e5588681d4e55bf

fileName=e6f208c012fc438d8d09c72a6272fc45

fileName=99371f05de894160a8ee6b8776aa5492

fileName=01336494f3804bdea8da71d552756052

fileName=82c35aa705a34c0cb1378f145eb4c69f

fileName=92315ae5910e41828296f0f468808a5d

fileName=f0f1e6ebaad6410aaa64e997a0f28b5a

fileName=477c9c50edc24c339e22ae997f8c8674

fileName=814f47f6b9ac47ed8fe9027bf4db9bde

fileName=8adc22da263941588a7644e65176682d

fileName=116ee790785847f7b9129f7fbf1f2ac2

fileName=227e6cf1bf334d0da3a57c46c655edcd

fileName=47b5fd5e03d84f4b945fa9d47a199174

fileName=900e240a183c461bba3c28e871341fb9

fileName=bbbd95ccd0b143dfbe5adc19292c0bf4

fileName=28450dfff97045c882f740a511b0d4fe

fileName=8ce2a10345f14bb987367653345e931d

fileName=7e90485d1dd84e638a68605883305afd

fileName=1d46823cef004254b4d4705ccaa94d6b

fileName=6c3d82c142954f48a754bf0a8e403812

fileName=1cd674231cb34a7f9c5d3595d0947daa

fileName=3ec4b8f1f4eb4b8897a0d369d8f8725e

......

这个应该也是没有重复的，利用的是Guid的唯一性，这种方法比较省事，但是不带时间信息在里面

所以，要生成真正唯一的文件名，要用最后二种方法

--- end ---

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