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

<%@ 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>

<%@ 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;
        }
    }

}