ASP.NET(c#)文件下载函数-优快云博客

本文介绍了一个用于下载文件的函数实现细节，包括如何处理重定向、获取文件扩展名、创建目录结构、读取并写入文件流等关键步骤。

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/// <summary>
/// 下载文件函数
/// </summary>
/// <param name="url">下载地址</param>
/// <param name="Path">保存路径</param>
/// <param name="typeName">类型:文件或图片</param>
        private bool DownFile(string url, string Path,string typeName)
        {
            try
             {
                 HttpWebRequest objHttpWebRequest;
                 HttpWebResponse objHttpWebResponse;
                 try
                 {
                     objHttpWebRequest = (HttpWebRequest)WebRequest.Create(url);//send
                     objHttpWebResponse = (HttpWebResponse)objHttpWebRequest.GetResponse();//get
                     objHttpWebRequest.AllowAutoRedirect = true;
                 }
                 catch
                 {
                     return false;
                 }

                 string AbsoluteUri = objHttpWebResponse.ResponseUri.AbsoluteUri;//It may be Redirect so is necessary to use the AbsoluteUri
                 string Extend = AbsoluteUri.Substring(AbsoluteUri.LastIndexOf(".") + 1);

                 string GuidName = Guid.NewGuid().ToString();
                 Path = Path + GuidName.Substring(0, 1);

                 DirectoryInfo objDirectoryInfo = new DirectoryInfo(Path);
                 if (objDirectoryInfo.Exists)
                 {

                 }
                 else
                 {
                     objDirectoryInfo.Create();
                 }

                 string FullName = Path + "//" + GuidName + "." + Extend;

                 Stream objStream = objHttpWebResponse.GetResponseStream();

                 Byte[] buffer = new Byte[256];

                 int bufferSizeCount = objStream.Read(buffer, 0, 256);

                 FileStream objFileStream = new FileStream(FullName, FileMode.Create, FileAccess.Write);

                 int sumBufferSizeCount = 0;

                 while (bufferSizeCount > 0)
                 {
                     Application.DoEvents();

                     objFileStream.Write(buffer, 0, bufferSizeCount);//
                     bufferSizeCount = objStream.Read(buffer, 0, 256);//
                     sumBufferSizeCount += bufferSizeCount;//
                     this.Text = string.Format("[总进度{0}/{1}] 下载进度{2}文件:{3}K {4}",currentIndex,totalCount, Extend, sumBufferSizeCount / 1024,sumBufferSizeCount);
                 }

                 objStream.Close();
                 objFileStream.Close();
                 objHttpWebResponse.Close();

                 FileInfo objFileInfo = new FileInfo(FullName);
                 int FileSize = Convert.ToInt32(objFileInfo.Length / 1024);

                 if (typeName == "image")
                 {
                     ImageFileName = GuidName;
                     ImageExtend = Extend;
                     ImageFileSize = FileSize;

                     if (File.Exists(FullName))
                     {
                         System.Drawing.Image image = System.Drawing.Image.FromFile(FullName);

                         this.pictureBox1.Image = image;
                     }

                 }
                 else if(typeName == "file")
                 {
                     FileFileName = GuidName;
                     FileExtend = Extend;
                     FileFileSize = FileSize;
                 }

                 this.Refresh();

                 return true;

            }
            catch
            {
                return false;
            }