http://www.cnblogs.com/Warmsunshine/archive/2011/03/05/1971521.html
/// <summary>
/// 生成6位随机数
/// </summary>
/// <param name="length"></param>
/// <returns></returns>
public string GetRandomString(int len)
{
string s = "123456789abcdefghijklmnpqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ";
string reValue = string.Empty;
Random rd = new Random();
while (reValue.Length < len)
{
string s1 = s[rd.Next(0, s.Length)].ToString();
if (reValue.IndexOf(s1) == -1)
reValue += s1;
}
return reValue;
}
