PetShop学习日记1——一般处理程序

Page类实现了ProcessRequest（）方法，通过它可以设置Page对象的Request和Response属性，从而完成对用户请求/响应的控制。

 

<%@ WebHandler Language="C#" Class="Handler" %>

using System;
using System.Drawing;
using System.Drawing.Imaging;
using System.Text;
using System.Web;
using System.Web.SessionState;

public class Handler : IHttpHandler, IRequiresSessionState {

    public void ProcessRequest(HttpContext context) {
       context.Response.ContentType = "image/gif";
       //建立Bitmap对象，绘图
       Bitmap basemap = new Bitmap(200, 60);
       Graphics graph = Graphics.FromImage(basemap);
       graph.FillRectangle(new SolidBrush(Color.White), 0, 0, 200, 60);
       Font font = new Font(FontFamily.GenericSerif, 48, FontStyle.Bold, GraphicsUnit.Pixel);
       Random r = new Random();
       string letters = "ABCDEFGHIJKLMNPQRSTUVWXYZ";
       string letter;
       StringBuilder s = new StringBuilder();
       
       //添加随机的五个字母
       for (int x = 0; x < 5; x++) {
           letter = letters.Substring(r.Next(0, letters.Length - 1), 1);
           s.Append(letter);
           graph.DrawString(letter, font, new SolidBrush(Color.Black), x * 38, r.Next(0, 15));
       }
       
       //混淆背景
       Pen linePen = new Pen(new SolidBrush(Color.Black), 2);
       for (int x = 0; x < 6; x++)
           graph.DrawLine(linePen, new Point(r.Next(0, 199), r.Next(0, 59)), new Point(r.Next(0, 199), r.Next(0, 59)));
              
       //将图片保存到输出流中       
       basemap.Save(context.Response.OutputStream, ImageFormat.Gif);
       context.Session["CheckCode"] = s.ToString();   //如果没有实现IRequiresSessionState，则这里会出错，也无法生成图片
       context.Response.End();      
    }

    public bool IsReusable {
       get { return true; }
    }
}

 

在新页面调用：    <img src="Handler.ashx" alt="图片验证码" />

再加入一个简单例子

 

<%@ WebHandler Language="C#" Class="Handler2" %>

using System;
using System.Web;

public class Handler2 : IHttpHandler {
    
    public void ProcessRequest (HttpContext context) {
        context.Response.Write("<H1>This is an HttpHandler Test.</H1>");
        context.Response.Write("<p>Your Browser:</p>");
        context.Response.Write("Type: " + context.Request.Browser.Type + "<br>");
        context.Response.Write("Version: " + context.Request.Browser.Version);
    }
 
    public bool IsReusable {
        get {
            return false;
        }
    }

}

 

View的内容决定了Model的值，而Model的值反过来又决定了View的现实内容。