我如何在c#中生成一个随机的8个字符的字母数字字符串?
当前回答
对于加密和非加密，有效地:
public static string GenerateRandomString(int length, string charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890") =>
new Random().GenerateRandomString(length, charset);
public static string GenerateRandomString(this Random random, int length, string charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890") =>
RandomString(random.NextBytes, length, charset.ToCharArray());
public static string GenerateRandomCryptoString(int length, string charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890")
{
using (var crypto = new System.Security.Cryptography.RNGCryptoServiceProvider())
return crypto.GenerateRandomCryptoString(length, charset);
}
public static string GenerateRandomCryptoString(this RNGCryptoServiceProvider random, int length, string charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890") =>
RandomString(random.GetBytes, length, charset.ToCharArray());
private static string RandomString(Action<byte[]> fillRandomBuffer, int length, char[] charset)
{
if (length < 0)
throw new ArgumentOutOfRangeException(nameof(length), $"{nameof(length)} must be greater or equal to 0");
if (charset is null)
throw new ArgumentNullException(nameof(charset));
if (charset.Length == 0)
throw new ArgumentException($"{nameof(charset)} must contain at least 1 character", nameof(charset));
var maxIdx = charset.Length;
var chars = new char[length];
var randomBuffer = new byte[length * 4];
fillRandomBuffer(randomBuffer);
for (var i = 0; i < length; i++)
chars[i] = charset[BitConverter.ToUInt32(randomBuffer, i * 4) % maxIdx];
return new string(chars);
}
使用生成器和LINQ。不是最快的选项(特别是因为它不会一次生成所有字节)，但相当整洁和可扩展:
private static readonly Random _random = new Random();
public static string GenerateRandomString(int length, string charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890") =>
new string(_random.GetGenerator().RandomChars(charset.ToCharArray()).Take(length).ToArray());
public static string GenerateRandomCryptoString(int length, string charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890")
{
using (var crypto = new System.Security.Cryptography.RNGCryptoServiceProvider())
return new string(crypto.GetGenerator().RandomChars(charset.ToCharArray()).Take(length).ToArray());
}
public static IEnumerable<char> RandomChars(this Func<uint, IEnumerable<uint>> randomGenerator, char[] charset)
{
if (charset is null)
throw new ArgumentNullException(nameof(charset));
if (charset.Length == 0)
throw new ArgumentException($"{nameof(charset)} must contain at least 1 character", nameof(charset));
return randomGenerator((uint)charset.Length).Select(r => charset[r]);
}
public static Func<uint, IEnumerable<uint>> GetGenerator(this Random random)
{
if (random is null)
throw new ArgumentNullException(nameof(random));
return GeneratorFunc_Inner;
IEnumerable<uint> GeneratorFunc_Inner(uint maxValue)
{
if (maxValue > int.MaxValue)
throw new ArgumentOutOfRangeException(nameof(maxValue));
return Generator_Inner();
IEnumerable<uint> Generator_Inner()
{
var randomBytes = new byte[4];
while (true)
{
random.NextBytes(randomBytes);
yield return BitConverter.ToUInt32(randomBytes, 0) % maxValue;
}
}
}
}
public static Func<uint, IEnumerable<uint>> GetGenerator(this System.Security.Cryptography.RNGCryptoServiceProvider random)
{
if (random is null)
throw new ArgumentNullException(nameof(random));
return Generator_Inner;
IEnumerable<uint> Generator_Inner(uint maxValue)
{
var randomBytes = new byte[4];
while (true)
{
random.GetBytes(randomBytes);
yield return BitConverter.ToUInt32(randomBytes, 0) % maxValue;
}
}
}
一个更简单的版本，使用LINQ只用于非加密字符串:
private static readonly Random _random = new Random();
public static string RandomString(int length, string charset = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890") =>
new string(_random.GenerateChars(charset).Take(length).ToArray());
public static IEnumerable<char> GenerateChars(this Random random, string charset)
{
if (charset is null) throw new ArgumentNullException(nameof(charset));
if (charset.Length == 0) throw new ArgumentException($"{nameof(charset)} must contain at least 1 character", nameof(charset));
return random.Generator(charset.Length).Select(r => charset[r]);
}
public static IEnumerable<int> Generator(this Random random, int maxValue)
{
if (random is null) throw new ArgumentNullException(nameof(random));
return Generator_Inner();
IEnumerable<int> Generator_Inner() { while (true) yield return random.Next(maxValue); }
}
其他回答
不是100%确定，因为我没有测试这里的每个选项，但在我测试的选项中，这个是最快的。用秒表计时，它显示9-10滴答，所以如果速度比安全更重要，试试这个:
private static Random random = new Random();
public static string Random(int length)
{
var stringChars = new char[length];
for (int i = 0; i < length; i++)
{
stringChars[i] = (char)random.Next(0x30, 0x7a);
return new string(stringChars);
}
}
我听说LINQ是新的黑色，所以下面是我使用LINQ的尝试:
private static Random random = new Random();
public static string RandomString(int length)
{
const string chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
return new string(Enumerable.Repeat(chars, length)
.Select(s => s[random.Next(s.Length)]).ToArray());
}
(注意:Random类的使用使得它不适用于任何与安全性相关的事情，比如创建密码或令牌。如果你需要强随机数生成器，请使用RNGCryptoServiceProvider类。)
一种简单且高度安全的方法可能是生成加密Aes密钥。
public static string GenerateRandomString()
{
using Aes crypto = Aes.Create();
crypto.GenerateKey();
return Convert.ToBase64String(crypto.Key);
}
另一种选择是使用Linq并将随机字符聚合到stringbuilder中。
var chars = "abcdefghijklmnopqrstuvwxyz123456789".ToArray();
string pw = Enumerable.Range(0, passwordLength)
.Aggregate(
new StringBuilder(),
(sb, n) => sb.Append((chars[random.Next(chars.Length)])),
sb => sb.ToString());
尝试将两部分结合起来:独特(序列、计数器或日期)和随机
public class RandomStringGenerator
{
public static string Gen()
{
return ConvertToBase(DateTime.UtcNow.ToFileTimeUtc()) + GenRandomStrings(5); //keep length fixed at least of one part
}
private static string GenRandomStrings(int strLen)
{
var result = string.Empty;
using (var gen = new RNGCryptoServiceProvider())
{
var data = new byte[1];
while (result.Length < strLen)
{
gen.GetNonZeroBytes(data);
int code = data[0];
if (code > 48 && code < 57 || // 0-9
code > 65 && code < 90 || // A-Z
code > 97 && code < 122 // a-z
)
{
result += Convert.ToChar(code);
}
}
return result;
}
}
private static string ConvertToBase(long num, int nbase = 36)
{
const string chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"; //if you wish to make the algorithm more secure - change order of letter here
// check if we can convert to another base
if (nbase < 2 || nbase > chars.Length)
return null;
int r;
var newNumber = string.Empty;
// in r we have the offset of the char that was converted to the new base
while (num >= nbase)
{
r = (int)(num % nbase);
newNumber = chars[r] + newNumber;
num = num / nbase;
}
// the last number to convert
newNumber = chars[(int)num] + newNumber;
return newNumber;
}
}
测试:
[Test]
public void Generator_Should_BeUnigue1()
{
//Given
var loop = Enumerable.Range(0, 1000);
//When
var str = loop.Select(x=> RandomStringGenerator.Gen());
//Then
var distinct = str.Distinct();
Assert.AreEqual(loop.Count(),distinct.Count()); // Or Assert.IsTrue(distinct.Count() < 0.95 * loop.Count())
}
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