asp.net 生成数字和字母组合的随机数

private static char[] constant = { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 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, 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 };

public string pxkt_GetCharFont(int strLength)
{
System.Text.StringBuilder newRandom = new System.Text.StringBuilder(62);
Random rd= new Random();
for(int i=0;i<strLength;i++)
{
newRandom.Append(constant[rd.Next(62)]);
}
return newRandom.ToString();
}