asp.net一般处理程序（.ashx）动态生成验证码案例。

{使用一般处理程序动态生成验证码}

1.新建WebSite项目，添加一般处理程序命名为 yzm.ashx，添加如下代码：

public void ProcessRequest(HttpContext context)
{

//将context.Response.ContentType = "text/plain";修改为context.Response.ContentType = "image/JPEG";
context.Response.ContentType = "image/JPEG";
using (System.Drawing.Bitmap bitmap =
new System.Drawing.Bitmap(150, 50))
{
using (System.Drawing.Graphics grapgics =
System.Drawing.Graphics.FromImage(bitmap))
{

//测试示例
/*grapgics.DrawString("哈喽",
new System.Drawing.Font("宋体", 20),
System.Drawing.Brushes.Blue
, new System.Drawing.PointF(0, 0));

System.Drawing.Pen pen = (System.Drawing.Pen)
System.Drawing.Pens.Red.Clone();
pen.Width = 3;
grapgics.DrawEllipse(pen, new System.Drawing.Rectangle(20, 20, 10, 10));

bitmap.Save(context.Response.OutputStream,
System.Drawing.Imaging.ImageFormat.Jpeg);*/

//生成随机数
Random random = new Random();
int code = random.Next();
string strCode = code.ToString();

//存session
HttpContext.Current.Session["code"] = strCode;
grapgics.DrawString(strCode,
new System.Drawing.Font("宋体", 20),
System.Drawing.Brushes.Blue
, new System.Drawing.PointF(0, 0));
bitmap.Save(context.Response.OutputStream,
System.Drawing.Imaging.ImageFormat.Jpeg);

}
}

//本身就有的
context.Response.Write("Hello World");
}

2.新建webApplication。

在<div>中添加<img src="yzm.ashx"/>

添加TextBox 和Button,Button的单击事件如下

protected void Button1_Click(object sender, EventArgs e)
{
string stryzm = Convert.ToString(Session["code"]);
if (stryzm==TextBox1.Text)
{
Response.Write("正确");
}
else
{
Response.Write("错误");
}
}

3.随后即可在WebApplication中进行测试。