ASP.NET生成验证码的方法

 using System; using System.Collections.Generic; using System.Drawing; using System.Linq; using System.Web; using System.Web.SessionState; namespace Project_Practice { /// 
 /// Handler1 的摘要说明 /// 
 public class Handler1 : IHttpHandler,IRequiresSessionState { public void ProcessRequest(HttpContext context) { //选取的颜色 Color[] colors = { Color.White }; //通过Bitmap构造Image Image img = new Bitmap(100, 60); //Graphics绘画Image Graphics graphics = Graphics.FromImage(img); Random random = new Random(DateTime.Now.Millisecond); //验证码的四位数 int charNum1 = random.Next('0', '9' + 1); int charNum2 = random.Next('0', '9' + 1); int charNum3 = random.Next('0', '9' + 1); int charNum4 = random.Next('0', '9' + 1); //把生成的随机数变成字符串，通过char进行转换 string validCode = string.Format($"{(char)charNum1}{(char)charNum2}{(char)charNum3}{(char)charNum4}"); //放进Session进行存储，记得继承接口，否则疯狂报空指针 context.Session["verification_Code"] = validCode; //字体的大小和类别 Font font = new Font("宋体", 24); //随机的颜色 Brush brush1 = new SolidBrush(colors[random.Next(0, colors.Length - 1)]); //DrawString的四个参数，第一个是要写的字符，第二个是字体，第三个是颜色，第四个是坐标x,y graphics.DrawString(((char)charNum1).ToString(), font, brush1, 7, -3); Brush brush2 = new SolidBrush(colors[random.Next(0, colors.Length - 1)]); graphics.DrawString(((char)charNum2).ToString(), font, brush2, 26, -9); Brush brush3 = new SolidBrush(colors[random.Next(0, colors.Length - 1)]); graphics.DrawString(((char)charNum3).ToString(), font, brush3, 50, 0); Brush brush4 = new SolidBrush(colors[random.Next(0, colors.Length - 1)]); graphics.DrawString(((char)charNum4).ToString(), font, brush4, 70, -7); //保存，格式 context.Response.ContentType = "image/jpeg"; img.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg); //释放资源 graphics.Dispose(); img.Dispose(); } public bool IsReusable { get { return false; } } } }

 <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="verification_Code.aspx.cs" Inherits="Project_Practice.verification_Code" %>