using System;
using System.Web;
using System.Drawing;
using System.Web.SessionState;
public class ValidateCode : IHttpHandler,IRequiresSessionState {
public void ProcessRequest(HttpContext context)
{
//System.Threading.Thread.Sleep(5000);
context.Response.ContentType = "image/jpeg";
string code = GetRndStr();
context.Session["code"] = code;
using (Bitmap img = CreateImages(code, "ch"))
{
img.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
}
}
public bool IsReusable
{
get
{
return false;
}
}
/// <summary>
/// 数字随机数
/// </summary>
/// <returns></returns>
private string GetRndNum()
{
string code = string.Empty;
Random random = new Random();
for (int i = 0; i < 4; i++)
{
code += random.Next(9);
}
return code;
}
/// <summary>
/// 英文随机
/// </summary>
/// <returns></returns>
private string GetRndStr()
{
string Vchar = "A,B,C,D,E,F,G,H,I,J,K,L,M,N,O,P,Q,R,S,T,U,V,W,X,Y,Z";
string[] VcArray = Vchar.Split(',');
string checkCode = string.Empty;
Random rand = new Random();
for (int i = 0; i < 4; i++)
{
int t = rand.Next(VcArray.Length);
checkCode += VcArray[t];
}
return checkCode;
}
/// <summary>
/// 中文随机
/// </summary>
/// <returns></returns>
private string GetRndCh()
{
System.Text.Encoding gb = System.Text.Encoding.Default;//获取GB2312编码页（表）
object[] bytes = CreateRegionCode(4);//生4个随机中文汉字编码
string[] str = new string[4];
System.Text.StringBuilder sb = new System.Text.StringBuilder();
for (int i = 0; i < 4; i++)
{
//根据汉字编码的字节数组解码出中文汉字
str[i] = gb.GetString((byte[])Convert.ChangeType(bytes[i], typeof(byte[])));
sb.Append(str[i].ToString());
}
return sb.ToString();
}
/// <summary>
/// 产生随机中文字符
/// </summary>
/// <param name="strlength"></param>
/// <returns></returns>
private static object[] CreateRegionCode(int strlength)
{
//定义一个字符串数组储存汉字编码的组成元素
string[] rBase = new String[16] { "0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };
Random rnd = new Random();
object[] bytes = new object[strlength];
for (int i = 0; i < strlength; i++)
{
//区位码第1位
int r1 = rnd.Next(11, 14);
string str_r1 = rBase[r1].Trim();
//区位码第2位
rnd = new Random(r1 * unchecked((int)DateTime.Now.Ticks) + i);
int r2;
if (r1 == 13)
{
r2 = rnd.Next(0, 7);
}
else
{
r2 = rnd.Next(0, 16);
}
string str_r2 = rBase[r2].Trim();
//区位码第3位
rnd = new Random(r2 * unchecked((int)DateTime.Now.Ticks) + i);//更换随机种子
int r3 = rnd.Next(10, 16);
string str_r3 = rBase[r3].Trim();
//区位码第4位
rnd = new Random(r3 * unchecked((int)DateTime.Now.Ticks) + i);
int r4;
if (r3 == 10)
{
r4 = rnd.Next(1, 16);
}
else if (r3 == 15)
{
r4 = rnd.Next(0, 15);
}
else
{
r4 = rnd.Next(0, 16);
}
string str_r4 = rBase[r4].Trim();
//定义两个字节变量存储产生的随机汉字区位码
byte byte1 = Convert.ToByte(str_r1 + str_r2, 16);
byte byte2 = Convert.ToByte(str_r3 + str_r4, 16);
//将两个字节变量存储在字节数组中
byte[] str_r = new byte[] { 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;
}
/// <summary>
/// 画图片的背景图+干扰线
/// </summary>
/// <param name="checkCode"></param>
/// <returns></returns>
private Bitmap CreateImages(string checkCode, string type)
{
int step = 0;
if (type == "ch")
{
step = 5;//中文字符，边界值做大
}
int iwidth = (int)(checkCode.Length * (13 + step));
System.Drawing.Bitmap image = new System.Drawing.Bitmap(iwidth, 22);
Graphics g = Graphics.FromImage(image);
g.Clear(Color.White);//清除背景色
Color[] c = { Color.Black, Color.Red, Color.DarkBlue, Color.Green, Color.Orange, Color.Brown, Color.DarkCyan, Color.Purple };//定义随机颜色
string[] font = { "Verdana", "Microsoft Sans Serif", "Comic Sans MS", "Arial", "宋体" };
Random rand = new Random();
for (int i = 0; i < 50; i++)
{
int x1 = rand.Next(image.Width);
int x2 = rand.Next(image.Width);
int y1 = rand.Next(image.Height);
int y2 = rand.Next(image.Height);
g.DrawLine(new Pen(Color.LightGray, 1), x1, y1, x2, y2);//根据坐标画线
}
for (int i = 0; i < checkCode.Length; i++)
{
int cindex = rand.Next(7);
int findex = rand.Next(5);
Font f = new System.Drawing.Font(font[findex], 10, System.Drawing.FontStyle.Bold);
Brush b = new System.Drawing.SolidBrush(c[cindex]);
int ii = 4;
if ((i + 1) % 2 == 0)
{
ii = 2;
}
g.DrawString(checkCode.Substring(i, 1), f, b, 3 + (i * (12 + step)), ii);
}
g.DrawRectangle(new Pen(Color.Black, 0), 0, 0, image.Width - 1, image.Height - 1);
System.IO.MemoryStream ms = new System.IO.MemoryStream();
return image;
}
}
注意：在一般处理程序里面使用session必须实现IRequiresSessionState接口，命名空间using System.Web.SessionState;
看不清图片，点击异步换张图片
<img id="imgCode" src="ValidateCode.ashx" onclick="this.src='ValidateCode.ashx?ran='+ new Date()" style="cursor:pointer" title="看不清？" />
Jquery实现
$("#imgCode").arr("src","ValidateCode.ashx?ran=" + new Date());
