生成随机字符串

///Burgess.qian
///Date:2017-09-05
///生成随机字符串
///</summary>
///<param name="length">目标字符串的长度</param>
///<param name="useNum">是否包含数字，1=包含，默认为包含</param>
///<param name="useLow">是否包含小写字母，1=包含，默认为包含</param>
///<param name="useUpp">是否包含大写字母，1=包含，默认为包含</param>
///<param name="useSpe">是否包含特殊字符，1=包含，默认为不包含</param>
///<param name="custom">要包含的自定义字符，直接输入要包含的字符列表</param>
///<returns>指定长度的随机字符串</returns>
public static string GetRandomString(int length, bool useNum, bool useLow, bool useUpp, bool useSpe, string custom)
{
byte[] b = new byte[4];
new System.Security.Cryptography.RNGCryptoServiceProvider().GetBytes(b);
Random r = new Random(BitConverter.ToInt32(b, 0));
string s = null, str = custom;
if (useNum == true) { str += "0123456789"; }
if (useLow == true) { str += "abcdefghijklmnopqrstuvwxyz"; }
if (useUpp == true) { str += "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; }
if (useSpe == true) { str += "!#$%&()+-<=>?@[]^_`{}~"; }
for (int i = 0; i < length; i++)
{
s += str.Substring(r.Next(0, str.Length - 1), 1);
}
return s;
}