The ASP. NET MVC Authentication Code class uses

Verification Code Class

Namespace QJW.  verifycode{//Usage://public filecontentresult createvalidate ()//{//Validatecode Vcode = new Validatecode ();  String code = Vcode.createvalidatecode (5);  session["Validatecode"] = code;  byte[] bytes = vcode.createvalidategraphic (code);  Return File (bytes, "Image/jpeg"); } public class Validatecode {public Validatecode () {}///<summary>/////The maximum length of the verification code//</    summary> public int MaxLength {get {return 10;}    }///<summary>///The minimum length of the Verification Code///</summary> public int MinLength {get {return 1;}    }///<summary>//Generate verification codes///</summary>//<param name= "Length" > Specify the lengths of the Captcha </param> <returns></returns> public string Createvalidatecode (int length) {int[] randmembers = new int[      Length];      int[] validatenums = new Int[length];      String validatenumberstr = ""; Generates the starting sequence value int seekseek = unchecked ((int) DateTime.Now.Ticks);      Random Seekrand = new Random (Seekseek);      int beginseek = (int) seekrand.next (0, Int32.maxvalue-length * 10000);      Int[] seeks = new Int[length];        for (int i = 0; i < length; i++) {Beginseek + = 10000;      Seeks[i] = Beginseek;        }//Generate random numbers for (int i = 0; i < length; i++) {Random rand = new random (seeks[i]);        int pownum = 1 * (int) Math.pow (ten, length); Randmembers[i] = rand.      Next (Pownum, Int32.MaxValue); }//extract random numbers for (int i = 0; i < length; i++) {string numstr = Randmembers[i].        ToString ();        int numlength = Numstr.length;        Random rand = new Random (); int numposition = rand.        Next (0, numLength-1);      Validatenums[i] = Int32.Parse (numstr.substring (numposition, 1)); }//Generate Verification code for (int i = 0; i < length; i++) {validatenumberstr + = Validatenums[i].      ToString ();    } return VALIDATENUMBERSTR; }//&LT;summary>///Create a picture of the captcha///</summary>//<param name= "containspage" > Page object to be exported </param>      <param name= "Validatenum" > Verification Code </param> Public byte[] Createvalidategraphic (string validatecode) {      Bitmap image = new Bitmap ((int) math.ceiling (validatecode.length * 12.0), 22);      Graphics g = graphics.fromimage (image);        try {//Generate random generator randomly random = new random ();        Empty the picture background color g.clear (color.white); The interference line for the picture is (int i = 0; i <; i++) {int x1 = random. Next (image.          Width); int x2 = random. Next (image.          Width); int y1 = random. Next (image.          Height); int y2 = random. Next (image.          Height);        G.drawline (New Pen (color.silver), x1, y1, x2, y2); } font font = new Font ("Arial", FontStyle.Bold |        Fontstyle.italic)); LinearGradientBrush brush = new LinearGradientBrush (new Rectangle (0, 0, image. Width, image. Height), COLOR.BLUE, color.darkred, 1.2f, true);        g.DrawString (Validatecode, Font, Brush, 3, 2); The foreground of the painting picture interferes with the point for (int i = 0; i <; i++) {int x = random. Next (image.          Width); int y = random. Next (image.          Height); Image. SetPixel (x, Y, Color.FromArgb (random.        Next ())); }//Draw the border line of the picture G.drawrectangle (new Pen (Color.silver), 0, 0, image. Width-1, image.        HEIGHT-1);        Save picture Data MemoryStream stream = new MemoryStream (); Image.        Save (stream, imageformat.jpeg); Output picture stream return stream.      ToArray ();        } finally {g.dispose (); Image.      Dispose (); }}///<summary> Get the length of the CAPTCHA image////</summary>//<param name= "Validatenumlength" > The length of the Verification code      Degrees </param>///<returns></returns> public static int getimagewidth (int validatenumlength) {    return (int) (VALIDATENUMLENGTH * 12.0); }///<summary>//Get the height of the captcha///&LT;/SUMMARY&GT    <returns></returns> public static Double Getimageheight () {return 22.5; }  }}

How to use

Public Filecontentresult createvalidate () {  Validatecode vcode = new Validatecode ();  String code = Vcode.createvalidatecode (5);  session["Validatecode"] = code;  byte[] bytes = vcode.createvalidategraphic (code);   Return File (bytes, "Image/jpeg");}

Html
<a href= "javascript:;" onclick= "Reloadcode ();" ></a>
View JS

function Reloadcode () {    var verify = document.getElementById (' Safecode ');    Verify.setattribute (' src ', '/common/createvalidate ' + math.random ());  }

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