using System;
using System.Net;
using System.IO;
using System.Text;

namespace mynamespace
{
    public class Downloader
    {
        /// <summary>
        /// 下載圖片
        /// </summary>
        /// <param name="picUrl">圖片Http地址</param>
        /// <param name="savePath">儲存路徑</param>
        /// <param name="timeOut">Request最大請求時間，如果為-1則無限制</param>
        /// <returns></returns>
        public static bool DownloadPicture(string picUrl, string savePath,int timeOut)
        {
            bool value = false;
            WebResponse response = null;
            Stream stream = null;
            try
            {
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(picUrl);
                if (timeOut != -1) request.Timeout = timeOut;
                response = request.GetResponse();
                stream = response.GetResponseStream();
                if (!response.ContentType.ToLower().StartsWith("text/"))
                    value = SaveBinaryFile(response, savePath);
            }
            finally
            {
                if(stream!=null) stream.Close();
                if (response != null) response.Close();
            }
            return value;
        }
private static bool SaveBinaryFile(WebResponse response, string savePath)
        {
            bool value = false;
            byte[] buffer = new byte[1024];
            Stream outStream = null;
            Stream inStream = null;
            try
            {
                if (File.Exists(savePath)) File.Delete(savePath);
                outStream = System.IO.File.Create(savePath);
                inStream = response.GetResponseStream();
                int l;
                do
                {
                    l = inStream.Read(buffer, 0, buffer.Length);
                    if (l > 0) outStream.Write(buffer, 0, l);
                } while (l > 0);
                value = true;
            }
            finally
            {
                if(outStream!=null) outStream.Close();
                if(inStream!=null) inStream.Close();
            }
            return value;
        }
    }
}


//呼叫
public void DownloadImg()
{
            string imgUrl = "http://static.sporttery.cn/images/2014/12/10/15-1412100T3021H.png";
            string imgFileName = imgUrl.Substring(imgUrl.LastIndexOf('/')+1);
            Downloader.DownloadPicture(imgUrl, imgFileName, 300);
}