ASP.NET笔记之 Httphandler的操作详解

1、httphandler

实例1：通过生成一张动态图片输出客户端的IP地址、操作系统类型、浏览器类型
代码如下:
<%@ WebHandler Language="C#" Class="visitor" %>

using System;
using System.Web;

public class visitor : IHttpHandler {

    public void ProcessRequest(HttpContext context)
    {
        context.Response.ContentType = "image/JPEG";
        using (System.Drawing.Bitmap bitImage = new System.Drawing.Bitmap(330, 300))
        {
            //设置画布
            using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitImage))
            {
                //IP
                g.DrawString("IP:" + context.Request.UserHostAddress, new System.Drawing.Font("宋体", 20), System.Drawing.Brushes.Red, new System.Drawing.PointF(0, 0));
                //操作系统
                g.DrawString("操作系统:" + context.Request.Browser.Platform, new System.Drawing.Font("宋体", 20), System.Drawing.Brushes.Red, new System.Drawing.PointF(0, 50));
                //浏览器
                g.DrawString("浏览器:" + context.Request.Browser.Type, new System.Drawing.Font("宋体", 20), System.Drawing.Brushes.Red, new System.Drawing.PointF(0, 100));
            }
            //保存到输出流中
            bitImage.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);

        }
    }

    public bool IsReusable {
        get {
            return false;
        }
    }

}

实例2：通过“下载”连接，弹出用户附件保存

html代码：<a href="dowload.ashx">下载</a>
代码如下:
<%@ WebHandler Language="C#" Class="dowload" %>

using System;
using System.Web;

public class dowload : IHttpHandler {

    public void ProcessRequest(HttpContext context)
    {
        string fileName = HttpUtility.UrlEncode("悲剧.jpg");
        context.Response.ContentType = "image/JPEG";

        //打开附件对话框  报文头header和设置它的值
        context.Response.AddHeader("Content-Disposition", "attachment:filename=" + fileName);
        context.Response.WriteFile("苹果.jpg");      
    }

    public bool IsReusable {
        get {
            return false;
        }
    }

}