生成指定长度随机字符串

/// <summary>
/// 生成指定长度随机字符串（由大写字母组成）
/// </summary>
public static string GenerateRandomFilename(int len)
{
char[] chars = new char[]{'A','B','C','D','E','F','G','H','I','J','K','L','M','N',
'O','P','Q','R','S','T','U','V','W','X','Y','Z'};
Random random = new Random(DateTime.Now.Millisecond);
string fileName = String.Empty;
for (int i = 0; i < len; i++)
{
int index = random.Next(0, 26);
fileName += chars[index];
}
return fileName;
}