C#下载图片，用户选择保存路径

Html代码

 1 <html xmlns="http://www.w3.org/1999/xhtml">
 2 <head>
 3     <title></title>
 4 </head>
 5 <body>
 6     <a href="ImgDownloadHandler.ashx">下载</a>
 7     <img src="http://10.1.18.59/CenterPointService/RainfallCenterTemp/20180319155952/20170601__20170930.png"
 8         alt="RainfallCenter" id="RainfallCenter" />
 9 </body>
10 </html>

C#一般处理程序代码

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI.MobileControls;
using System.Drawing;
using System.IO;
using System.Net;

namespace WebApplication1
{
    /// <summary>
    /// ImgDownloadHandler 的摘要说明
    /// </summary>
    public class ImgDownloadHandler : IHttpHandler
    {

        public void ProcessRequest(HttpContext context)
        {
            #region action 2 可以导出图片
            Stream stream = null;
            string UrlImg = "http://10.1.18.59/CenterPointService/RainfallCenterTemp/20180319155952/20170601__20170930.png";
            WebClient webClient = new WebClient();
            webClient.Credentials = CredentialCache.DefaultCredentials;
            //以数组的形式下载指定文件  
            byte[] byteData = webClient.DownloadData(UrlImg);
            stream = BytesToStream(byteData);
            string fileName = "20170601__20170930.png";//客户端保存的文件名              
            context.Response.ContentType = "application/octet-stream";
            //通知浏览器下载文件而不是打开  
            context.Response.AddHeader("Content-Disposition", "attachment;   filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
            context.Response.BinaryWrite(byteData);
            context.Response.Flush();
            context.Response.End(); 
            #endregion
        }
        /// <summary>  
        /// 将二进制转化为数据流  
        /// </summary>  
        /// <param name="bytes">二进制数组</param>  
        /// <returns></returns>  
        public Stream BytesToStream(byte[] bytes)
        {
            Stream stream = new MemoryStream(bytes);
            return stream;
        }
        /// <summary>  
        /// 将流转化为二进制数组  
        /// </summary>  
        /// <param name="stream"></param>  
        /// <returns></returns>  
        public byte[] StreamToBytes(Stream stream)
        {
            byte[] bytes = new byte[stream.Length];
            stream.Read(bytes, 0, bytes.Length);
            // 设置当前流的位置为流的开始     
            stream.Seek(0, SeekOrigin.Begin);
            return bytes;
        }

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

 

posted on 2018-03-20 09:55  Insein  阅读(3233)  评论(0)  编辑  收藏  举报

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