乱数認証コードの生成
///
///
///
public class Captcha
{
public static string randomCode = "";//
///
///
///
///
///
public static string CreateRandomCode(int codeLen)
{
string allChar = "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
string[] allCharAry = allChar.Split(',');
randomCode = "";
int temp = -1;
Random rand = new Random();
for (int i = 0; i < codeLen; i++)
{
if (temp != -1)
{
rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
}
int t = rand.Next(9);
if (temp == t)
{
return CreateRandomCode(codeLen);
}
temp = t;
randomCode += allCharAry[t];
}
return randomCode;
}
}
乱数は1つのクラスに単独で静的フィールドを使用し、静的フィールドは同じインスタンスで一意です.
///
///
///
///
private byte[] CreateValidGraphic()
{
string validateCode = Captcha.CreateRandomCode(codeLen);
Bitmap img = new Bitmap((int)Math.Ceiling(validateCode.Length * 16.0), 27);
Graphics g = Graphics.FromImage(img);
try
{
Random random = new Random();//
g.Clear(Color.White);//
for (int i = 0; i < 25; i++)//
{
int x1 = random.Next(img.Width);
int x2 = random.Next(img.Width);
int y1 = random.Next(img.Height);
int y2 = random.Next(img.Height);
g.DrawLine(new Pen(Color.Silver), x1, x2, y1, y2);
}
Font font = new Font("Arial", 13, (FontStyle.Bold | FontStyle.Italic));
LinearGradientBrush brush = new LinearGradientBrush(new Rectangle(0, 0, img.Width, img.Height), Color.Blue, Color.DarkRed, 1.2f, true);
g.DrawString(validateCode, font, brush, 3, 2);
for (int i = 0; i < 100; i++)//
{
int x = random.Next(img.Width);
int y = random.Next(img.Height);
img.SetPixel(x, y, Color.FromArgb(random.Next()));
}
g.DrawRectangle(new Pen(Color.Silver), 0, 0, img.Width - 1, img.Height - 1);//
MemoryStream stream = new MemoryStream();
img.Save(stream, ImageFormat.Jpeg);
return stream.ToArray();//
}
catch (Exception)
{
throw;
}
finally
{
g.Dispose();
img.Dispose();
}
}
画像検証コードを生成し、自分のニーズに合わせて調整する
///
///
///
///
[HttpGet]
public IActionResult GetCaptcha()
{
var bytes = CreateValidGraphic();
return File(bytes,@"image/Gif");
}
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