废话没有，代码（img.aspx.cs）：
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01 using System;
02 using System.Data;
03 using System.Configuration;
04 using System.Collections;
05 using System.Web;
06 using System.Web.Security;
07 using System.Web.UI;
08 using System.Web.UI.WebControls;
09 using System.Web.UI.WebControls.WebParts;
10 using System.Web.UI.HtmlControls;
11 using System.Drawing;
12
13 public partial class salt_img : System.Web.UI.Page
14 {
15 protected void Page_Load(object sender, EventArgs e)
16 {
17 string checkCode = CreateRandomCode(4);
18 Session["CheckCode"] = checkCode;
19 CreateImage(checkCode);
20 }
21
22 private string CreateRandomCode(int codeCount)
23 {
24 string allChar = "1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K,L,M,N,P,R,S,T,U,W,X,Y,Z";
25 string[] allCharArray = allChar.Split(',');
26 string randomCode = "";
27 int temp = -1;
28
29 Random rand = new Random();
30 for (int i = 0; i < codeCount; i++)
31 {
32 if (temp != -1)
33 {
34 rand = new Random(i * temp * ((int)DateTime.Now.Ticks));
35 }
36 int t = rand.Next(allCharArray.Length);
37 if (temp == t)
38 {
39 return CreateRandomCode(codeCount);
40 }
41 temp = t;
42 randomCode += allCharArray[t];
43 }
44 return randomCode;
45 }
46
47 private void CreateImage(string checkCode)
48 {
49 int iwidth = (int)(checkCode.Length * 13);
50 System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 20);
51 Graphics g = Graphics.FromImage(image);
52 Font f = new System.Drawing.Font("Arial", 12, System.Drawing.FontStyle.Bold);
53 Brush b = new System.Drawing.SolidBrush(Color.Black);
54 //g.FillRectangle(new System.Drawing.SolidBrush(Color.Blue),0,0,image.Width, image.Height);
55 g.Clear(Color.White);
56 g.DrawString(checkCode, f, b, 3, 3);
57
58 Pen blackPen = new Pen(Color.Black, 0);
59 Random rand = new Random();
60 for (int i = 0; i < 3; i++)//干扰线
61 {
62 int y = rand.Next(image.Height);
63 g.DrawLine(blackPen, 0, y, image.Width, y);
64 }
65
66 System.IO.MemoryStream ms = new System.IO.MemoryStream();
67 image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
68 Response.ClearContent();
69 Response.ContentType = "image/Jpeg";
70 Response.BinaryWrite(ms.ToArray());
71 g.Dispose();
72 image.Dispose();
73 }
74 }
代码：img.aspx （只留下下面的其余全部删除）
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1 <%@ Page Language="C#" AutoEventWireup="true" CodeFile="img.aspx.cs" Inherits="salt_img" %>
