使用ashx显示小图片

使用ashx显示小图片（不存在的小图）

ashx文件与.aspx文件类似，可以通过它来调用HttpHandler类，它免去了普通.aspx页面的控件解析以及页面处理的过程。.ashx文件适合产生供浏览器处理的、不需要回发处理的数据格式，例如用于生成动态图片、动态文本等内容。

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

using System;
using System.Web;
using System.Drawing;
using System.IO;

public class showpic : IHttpHandler {
   
    public void ProcessRequest (HttpContext context) {
        string pic = context.Request["pic"];
        Bitmap bit = new Bitmap(context.Server.MapPath("~/tp/image_cp/" + pic));

//context.Server.MapPath("~/tp/image_cp/" + pic)是图片路径哦
        //bit.Height
        MemoryStream ms=new MemoryStream();
        int newh=0;
        int neww=0;
        //
        if (bit.Width < 150 && bit.Height < 150)
        {
            newh = bit.Height;
            neww = bit.Width;
        }
        else
        {
            double pwidth = (double)bit.Width / 150;
            double pheight = (double)bit.Height / 150;
            if (pwidth > pheight)
            {
                neww = 150;
                newh = Convert.ToInt32(bit.Height / pwidth);
            }
            else
            {
                newh = 150;
                neww = Convert.ToInt32(bit.Width / pheight);
            }
        }
        //生成小图
        Bitmap newbit = new Bitmap(bit, neww, newh);
        newbit.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
        context.Response.ContentType = "image/jpeg";
        context.Response.StatusCode = 200;
        context.Response.BinaryWrite(ms.ToArray());
        //context.Response.BinaryWrite(
    }
 
    public bool IsReusable {
        get {
            return false;
        }
    }

}