Web Verification Code Writing

<%@ WebHandler language="C #"class="Show"%>usingSystem;usingsystem.web;usingSystem.Drawing;usingSystem.Web.SessionState;//IRequiresSessionState Namespaces Public classShow:ihttphandler, irequiressessionstate{ Public voidProcessRequest (HttpContext context) {context. Response.ContentType="Image/jpeg";//the type to outputBitmap img=NewBitmap ( -, -);//Create a blank chartGraphics gr = Graphics.fromimage (IMG);//which map to draw onFont font =NewFont ("Song Body", A, FontStyle.Bold);//Set FontSolidBrush brush =NewSolidBrush (Color.White);//Set BrushErl FillRectangle (Brush,0,0, -, -);//The shape the brush drawsBrush. Color = color.red;//Color        strings ="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"; stringstr =""; Random Rand=NewRandom ();//Initialize random number         for(inti =0; I <4; i++)        {            intstart = Rand. Next ( +);//generate a random start positionstr + = s.substring (Start,1).        ToString (); } context. session["Yanzheng"] =str; Erl DrawString (str, font, brush,0,0);//finished drawing the picture.//Save The picture with the response response streamimg. Save (context.    RESPONSE.OUTPUTSTREAM,SYSTEM.DRAWING.IMAGING.IMAGEFORMAT.JPEG); }      Public BOOLisreusable {Get {            return false; }    }}

Web Verification Code Writing