ASP.NET怎么实现中英文验证码

 
protected void Page_Load(object sender, EventArgs e) 
{ 
//获取GB2312编码页（表） 
/**//** 
* 生成中文验证验码所要使用的方法 
* 注，生成中文验证码时要改变一下生成验证码图片的宽度 
* var imageCode = new System.Drawing.Bitmap((int)Math.Ceiling((code.Length * 22.5)), 23); //定义图片的宽度和高度 
**/ 

//var gb = Encoding.GetEncoding("gb2312"); 

/**/////调用函数产生4个随机中文汉字编码 
//object[] bytes = CreateRegionCode(4); 

/**/////根据汉字编码的字节数组解码出中文汉字 
//var sbCode = new StringBuilder().Append(gb.GetString((byte[])Convert.ChangeType(bytes[0], typeof(byte[])))) 
// .Append(gb.GetString((byte[])Convert.ChangeType(bytes[1], typeof(byte[])))) 
// .Append(gb.GetString((byte[])Convert.ChangeType(bytes[2], typeof(byte[])))) 
// .Append(gb.GetString((byte[])Convert.ChangeType(bytes[3], typeof(byte[])))); 
//CreateCheckCodeImage(sbCode.ToString()); 

CreateCheckCodeImage(GenerateCheckCode()); //生成数字英文所要使用的方法 
} 

生成汉字验证码#region 生成汉字验证码 
/**//// <summary> 
/// 此函数在汉字编码范围内随机创建含两个元素的十六进制字节数组，每个字节数组代表一个汉字，并将四个字节数组存储在object数组中。 
/// </summary> 
/// <param name="strLength">代表需要产生的汉字个数</param> 
/// <returns></returns> 
static object[] CreateRegionCode(int strLength) 
{ 
var rBase = new[] 
{ 
"0","1","2","3","4","5","6","7","8","9","a","b","c","d","e","f" 
}; 

var random = new Random(); 
var bytes = new object[strLength]; 

/**//*每循环一次产生一个含两个元素的十六进制字节数组，并将其放入bject数组中 
每个汉字有四个区位码组成 
区位码第1位和区位码第2位作为字节数组第一个元素 
区位码第3位和区位码第4位作为字节数组第二个元素 
*/ 

for (int i = 0; i < strLength; i++) 
{ 
//区位码第1位 
var r1 = random.Next(11, 14); 
var str_r1 = rBase[r1].Trim(); 

random = new Random(r1 * unchecked((int)DateTime.Now.Ticks) + i); //更换随机数发生器的种子避免产生重复值 

var r2 = 0; 
if (r1 == 13) 
r2 = random.Next(0, 7); 
else 
r2 = random.Next(0, 16); 

var str_r2 = rBase[r2].Trim(); 

//区位码第3位 
random = new Random(r2 * unchecked((int)DateTime.Now.Ticks) + i); 
var r3 = random.Next(10, 16); 
var str_r3 = rBase[r3].Trim(); 

//区位码第4位 
random = new Random(r3 * unchecked((int)DateTime.Now.Ticks) + i); 
var r4 = 0; 
if (r3 == 10) 
r4 = random.Next(1, 16); 
else if (r3 == 15) 
r4 = random.Next(0, 15); 
else 
r4 = random.Next(0, 16); 

var str_r4 = rBase[r4].Trim(); 

var byte1 = Convert.ToByte(str_r1 + str_r2, 16); 
var byte2 = Convert.ToByte(str_r3 + str_r4, 16); 
//将两个字节变量存储在字节数组中 
var str_r = new[] { byte1, byte2 }; 

//将产生的一个汉字的字节数组放入object数组中 
bytes.SetValue(str_r, i); 
} 
return bytes; 
} 
#endregion 

生成图片#region 生成图片 
void CreateCheckCodeImage(string code) 
{ 
var imageCode = new System.Drawing.Bitmap((int)Math.Ceiling((code.Length * 12.5)), 23); //定义图片的宽度和高度 
var g = Graphics.FromImage(imageCode); //加载图片到画布上 

try 
{ 
var random = new Random(); 
g.Clear(Color.White); //清空图片背景色 

//画图片的背景噪音线 
for (int i = 0; i < 25; i++) 
{ 
var x1 = random.Next(imageCode.Width); 
var x2 = random.Next(imageCode.Width); 
var y1 = random.Next(imageCode.Height); 
var y2 = random.Next(imageCode.Height); 

g.DrawLine(new Pen(Color.Silver), new Point(x1, y1), new Point(x2, y2)); 
} 

var font = new System.Drawing.Font("Arial", 12F, System.Drawing.FontStyle.Bold | System.Drawing.FontStyle.Italic); 
var brush = new System.Drawing.Drawing2D.LinearGradientBrush( 
new Rectangle(0, 0, imageCode.Width, imageCode.Height), 
Color.Blue, Color.DarkRed, 1.2F, true); 
g.DrawString(code, font, brush, 2, 2); 

//画图片的前景噪音点 
for (int i = 0; i < 100; i++) 
{ 
var x = random.Next(imageCode.Width); 
var y = random.Next(imageCode.Height); 
imageCode.SetPixel(x, y, Color.FromArgb(random.Next())); 
} 

//画图片的边框线 
g.DrawRectangle(new Pen(Color.Silver), 0, 0, imageCode.Width - 1, imageCode.Height - 1); 
var ms = new System.IO.MemoryStream(); 
imageCode.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg); 

Response.ClearContent(); 
Response.ContentType = "image/Jpeg"; 
Response.BinaryWrite(ms.ToArray()); 
} 
finally 
{ 
g.Dispose(); 
imageCode.Dispose(); 
} 

} 
#endregion 

生成数据验证码#region 生成数据验证码 
private string GenerateCheckCode() 
{ 
int number; 
char code; 
string checkCode = String.Empty; 

var random = new Random(); 

for (int i = 0; i < 5; i++) 
{ 
number = random.Next(); 

if (number % 2 == 0) 
code = (char)('0' + (char)(number % 10)); 
else 
code = (char)('A' + (char)(number % 26)); 

checkCode += code.ToString(); 
} 
return checkCode; 
} 
#endregion