ASP.NET动态生成图片并下载

1.动态生成文字，采用string name=context .Request ["name"];获取URL传递的参数，传递格式为“*.ashx?name=yioo”
 
2.文件下载：如果HttpHandler输出的是html,txt,jpeg等类型的信息，那么浏览器会直接显示，如果希望弹出保存对话框，则需要添加Header，添加context.Response.AddHeader("Content-Disposition","attachment:filename="+filename );
 
filename为建议保存的文件名称，如果包含中文，则需要增加HttpUtility.UrlEncode进行URL编码。
 
代码如下：
 
<%@ WebHandler Language="C#" Class="动态文字" %>
 
using System;
using System.Web;
 
public class 动态文字: IHttpHandler {
   
    public void ProcessRequest (HttpContext context) {
        context.Response.ContentType = "image/JPEG";
        //URL传递name参数，格式*.ashx?name=ngy
        string name=context .Request ["name"];
        //保存的文件名，中文需要用UrlEncode编码
        string filename = HttpUtility.UrlEncode("图片.jpg");
        //添加附近报文头信息
        context.Response.AddHeader("Content-Disposition","attachment:filename="+filename );
        String fullpath=HttpContext .Current .Server .MapPath ("22.jpg");
        using (System.Drawing.Bitmap bitmaip = new System.Drawing.Bitmap(fullpath))
        {
            using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmaip))
            {
                g.DrawString(name,new System.Drawing.Font("宋体",30),System .Drawing.Brushes .Red ,182,47);
            }
            bitmaip.Save(context .Response .OutputStream ,System .Drawing .Imaging .ImageFormat .Jpeg );
        }
        context.Response.WriteFile("22.jpg");
      
       
    }
 
    public bool IsReusable {
        get {
            return false;
        }
    }
 
}