以前在网上找到了很多关于中文验证码的文章（园子里也有，大家自己去找吧），但是都没有调测成功，总出现
The target '__Page' for the callback could not be found or did not implement ICallbackEventHandler不能ICallbackEventHandler回掉的错误，我进行了一下修正并整理，现在可以实现了中文验证码无刷新的操作，现特把全部源码分享给大家
核心源码
1
public
partial
class
Image : System.Web.UI.Page
2
{
3
protected void Page_Load(object sender, EventArgs e)
4
{
5 CreateCheckCodeImage(GenCode(4));
6
}
7 /**//// <summary>
8 /// '产生随机字符串
9 /// </summary>
10 /// <param name="num">随机出几个字符</param>
11 /// <returns>随机出的字符串</returns>
12 private string GenCode(int num)
13 {
14 string str = "的一是在不了有和人这中大为上个国我以要他时来用们...";
15 char[] chastr = str.ToCharArray();
16
17 string code = "";
18 Random rd = new Random();
19 int i;
20 for (i = 0; i < num; i++)
21 {
22 //code += source[rd.Next(0, source.Length)];
23 code += str.Substring(rd.Next(0, str.Length), 1);
24 }
25 return code;
26
27 }
28
29 /**//// <summary>
30 /// 生成图片（增加背景噪音线、前景噪音点）
31 /// </summary>
32 /// <param name="checkCode">随机出字符串</param>
33 private void CreateCheckCodeImage(string checkCode)
34 {
35 if (checkCode.Trim() == "" || checkCode == null)
36 return;
37 Session["Code"] = checkCode; //将字符串保存到Session中，以便需要时进行验证
38 System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)(checkCode.Length * 21.5), 22);
39 Graphics g = Graphics.FromImage(image);
40 try
41 {
42 //生成随机生成器
43 Random random = new Random();
44
45 //清空图片背景色
46 g.Clear(Color.White);
47
48 // 画图片的背景噪音线
49 int i;
50 for (i = 0; i < 25; i++)
51 {
52 int x1 = random.Next(image.Width);
53 int x2 = random.Next(image.Width);
54 int y1 = random.Next(image.Height);
55 int y2 = random.Next(image.Height);
56 g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);
57 }
58
59 Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold));
60 System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2F, true);
61 g.DrawString(checkCode, font, brush, 2, 2);
62
63 //画图片的前景噪音点
64 g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);
65 System.IO.MemoryStream ms = new System.IO.MemoryStream();
66 image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);
67 Response.ClearContent();
68 Response.ContentType = "image/Gif";
69 Response.BinaryWrite(ms.ToArray());
70
71 }
72 catch
73 {
74 g.Dispose();
75 image.Dispose();
76 }
77
78 }
public
partial
class
Image : System.Web.UI.Page2
{3
protected void Page_Load(object sender, EventArgs e)4
{5
CreateCheckCodeImage(GenCode(4));6
}7
/**//// <summary>8
/// '产生随机字符串9
/// </summary>10
/// <param name="num">随机出几个字符</param>11
/// <returns>随机出的字符串</returns>12
private string GenCode(int num)13
{14
string str = "的一是在不了有和人这中大为上个国我以要他时来用们...";15
char[] chastr = str.ToCharArray();16
17
string code = "";18
Random rd = new Random();19
int i;20
for (i = 0; i < num; i++)21
{22
//code += source[rd.Next(0, source.Length)];23
code += str.Substring(rd.Next(0, str.Length), 1);24
}25
return code;26
27
}28
29
/**//// <summary>30
/// 生成图片（增加背景噪音线、前景噪音点）31
/// </summary>32
/// <param name="checkCode">随机出字符串</param>33
private void CreateCheckCodeImage(string checkCode)34
{35
if (checkCode.Trim() == "" || checkCode == null)36
return;37
Session["Code"] = checkCode; //将字符串保存到Session中，以便需要时进行验证38
System.Drawing.Bitmap image = new System.Drawing.Bitmap((int)(checkCode.Length * 21.5), 22);39
Graphics g = Graphics.FromImage(image);40
try41
{42
//生成随机生成器43
Random random = new Random(); 44
45
//清空图片背景色46
g.Clear(Color.White); 47
48
// 画图片的背景噪音线49
int i;50
for (i = 0; i < 25; i++)51
{52
int x1 = random.Next(image.Width);53
int x2 = random.Next(image.Width);54
int y1 = random.Next(image.Height);55
int y2 = random.Next(image.Height);56
g.DrawLine(new Pen(Color.Silver), x1, y1, x2, y2);57
}58
59
Font font = new System.Drawing.Font("Arial", 12, (System.Drawing.FontStyle.Bold));60
System.Drawing.Drawing2D.LinearGradientBrush brush = new System.Drawing.Drawing2D.LinearGradientBrush(new Rectangle(0, 0, image.Width, image.Height), Color.Blue, Color.DarkRed, 1.2F, true);61
g.DrawString(checkCode, font, brush, 2, 2);62
63
//画图片的前景噪音点64
g.DrawRectangle(new Pen(Color.Silver), 0, 0, image.Width - 1, image.Height - 1);65
System.IO.MemoryStream ms = new System.IO.MemoryStream();66
image.Save(ms, System.Drawing.Imaging.ImageFormat.Gif);67
Response.ClearContent();68
Response.ContentType = "image/Gif";69
Response.BinaryWrite(ms.ToArray());70
71
}72
catch73
{74
g.Dispose();75
image.Dispose();76
}77
78
}
希望该源码只是一个抛砖引玉的作用，你可以进行修改，比如说改中文字库，字体背景噪音等等
默认帐号密码均为51aspx，这里用户登录只是一个验证的例子，没有其他功能
本文转自 liudao 博客园博客，原文链接：http://www.cnblogs.com/liudao/archive/2007/04/21/721993.html，如需转载请自行联系原作者
