一個ASP.NET檔案下載類

public static class FilesDownLoad
    {
        private static readonly Dictionary<string, string> MimeDic = new Dictionary<string, string>();

        static FilesDownLoad()
        {
            MimeDic.Add("text/plain", "txt");
            MimeDic.Add("image/jpeg", "jpg");
            MimeDic.Add("image/gif", "gif");
        }

        /// <summary>
        /// 下載檔案到指定目錄，並返回下載後存放的檔案路徑
        /// </summary>
        /// <param>網址</param>
        /// <param>存放目錄，如果該目錄中已存在與待下載檔案同名的檔案，那麼將自動重新命名</param>
        /// <returns>下載檔案存放的檔案路徑</returns>
        public static string DownLoadFile(Uri Uri, string savePath)
        {

            WebResponse q = WebRequest.Create(Uri).GetResponse();
            Stream s = q.GetResponseStream();
            var b = new BinaryReader(s);
            string file = CreateSavePath(savePath, Uri, q.ContentType);
            var fs = new FileStream(file, FileMode.Create, FileAccess.Write);
            fs.Write(b.ReadBytes((int)q.ContentLength), 0, (int)q.ContentLength);
            fs.Close();
            b.Close();
            s.Close();
            return file;
        }

        private static string CreateSavePath(string SaveCategory, Uri Uri, string ContentType)
        {
            if (Directory.Exists(SaveCategory) == false)
                Directory.CreateDirectory(SaveCategory);

            string ex = GetExtentName(ContentType);
            string up = null;
            string upne = null;
            if (Uri.LocalPath == "/")
            {
                //處理Url是網域名稱的情況
                up = upne = Uri.Host;
            }

            else
            {
                if (Uri.LocalPath.EndsWith("/"))
                {
                    //處理Url是目錄的情況
                    up = Uri.LocalPath.Substring(0, Uri.LocalPath.Length - 1);
                    upne = Path.GetFileName(up);
                }

                else
                {
                    //處理常規Url

                    up = Uri.LocalPath;
                    upne = Path.GetFileNameWithoutExtension(up);
                }
            }

            string name = string.IsNullOrEmpty(ex) ? Path.GetFileName(up) : upne + "." + ex;
            string fn = Path.Combine(SaveCategory, name);
            int x = 1;

            while (File.Exists(fn))
            {
                fn = Path.Combine(SaveCategory,
                                  Path.GetFileNameWithoutExtension(name) + "(" + x++ + ")" + Path.GetExtension(name));
            }

            return fn;
        }

        private static string GetExtentName(string ContentType)
        {
            foreach (string f in MimeDic.Keys)
            {
                if (ContentType.ToLower().IndexOf(f) >= 0) return MimeDic[f];
            }

            return null;
        }
    }

 

測試用法如下：

[TestFixture]
public class FileDownLoadTests
{
    [Test]
    [Ignore]
    public void 測試下載()
    {
        string d = @"D:\MyTest\Downloads";
        //首次下載

        Assert.AreEqual(@"D:\MyTest\Downloads\cf697a340f684bc1a9018e98.jpg",
                        FilesDownLoad.DownLoadFile(new Uri("http://hiphotos.baidu.com/huyangdiy/pic/item/cf697a340f684bc1a9018e98.jpg"), d));

        //第二次下載，遇到同名檔案，自動重新命名

        Assert.AreEqual(@"D:\MyTest\Downloads\cf697a340f684bc1a9018e98(1).jpg",
                        FilesDownLoad.DownLoadFile(new Uri("http://hiphotos.baidu.com/huyangdiy/pic/item/cf697a340f684bc1a9018e98.jpg"), d));

    }
}