.net几种文件下载的方法

.Net文件下载方式。。。。

　　之前在写上传文件、下载文件的时候，发现Response对象里面有好几种下载文件的方式，之后自己亲自实践了这几种方法，记录下以便以后复习。。。

 WriteFile文件下载

     public void getFile(string path, string fileName)
        {
            FileInfo fileInfo = new FileInfo(path);
            Response.Clear();
            Response.ClearContent();
            Response.ClearHeaders();
            Response.ContentType = "application/octet-stream";//设置输出流的 HTTP MIME 类型
            //Content-Disposition 为二进制格式提供已知MIME类型的“文件下载”对话框或建议动态内容的文件名的机会
            Response.AddHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));// URL 字符串进行编码，防止出现乱码
            //回应消息体的长度，以 字节 （8位为一字节）为单位
            Response.AddHeader("Content-Length", fileInfo.Length + "");
            //文件传输编码  二进制
            Response.AddHeader("Content-Transfer-Encoding", "binary");
            //指定文件的内容作为文件块直接写入 HTTP 响应输出流
            Response.WriteFile(fileInfo.FullName);
            Response.Flush();
            Response.End();        
        }

 BinaryWrite流文件下载

    public void getFile1(string path, string fileName)
        {
            FileStream stream = File.Open(path, FileMode.Open); // FileStream stream = new FileStream(path,FileMode.Open);  
            byte[] buffer = new byte[(int)stream.Length];
            stream.Read(buffer, 0, buffer.Length);
            stream.Close();//文件流需要手动关闭，或者用using自动关闭
            Response.Clear();
            Response.ContentType = "application/octet-stream";
            //通知浏览器下载    
            Response.AddHeader("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8));
            //将二进制字符串写入 HTTP 输出流,已经是二进制了，就不需要 Response.AddHeader("Content-Transfer-Encoding", "binary");
            Response.BinaryWrite(buffer);
            Response.Flush();
            Response.End();
        }

大文件分块下載

 public void getFile2(string path, string fileName)
        {
            FileInfo fileInfo = new FileInfo(path);
            if (fileInfo.Exists)
            {
                const long standardSize = 200*1024;//定义一个静态常量，每次读取200K，缓解服务器压力（大文件更好下载）
                FileStream stream = File.OpenRead(path);
                byte[] buffer = new byte[standardSize];
                long dataFielSize = stream.Length;//下载文件总大小 
                Response.Clear();
                Response.ContentType = "application/octet-stream";
                Response.AddHeader("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(fileName));
                Response.AddHeader("Content-Length", fileInfo.Length.ToString());
                Response.AddHeader("Content-Transfer-Encoding", "binary");
                Response.ContentEncoding = System.Text.Encoding.Default;
                if (dataFielSize > 0 && Response.IsClientConnected)
                {
                    int readLengtn = stream.Read(buffer, 0, (int)standardSize);
                    Response.OutputStream.Write(buffer, 0, readLengtn);
                    Response.Flush();
                    dataFielSize = dataFielSize - readLengtn;
                }
                stream.Close();
                Response.Close();
            }
        }

TransmitFile文件下载

   public void getFile4(string path, string fileName)
        {
            Response.Clear();
            Response.ContentType = "application/octet-stream";
            Response.AddHeader("Content-Disposition", "attachment;filename=" + System.Web.HttpUtility.UrlEncode(fileName));
            Response.TransmitFile(path);
        }

 JSWindow打开文件 

   public void getFile3(string path)
        {
            Response.Write("<script>window.open('" + path + "')</script>");//文件打开可以下载，图片打开就是在线预览
        }

方法调用函数如下：

  protected void btnn_Click(object sender, EventArgs e)
        {
            Button btn = (Button)sender;
            //var aa = Request.MapPath("../Pages/uploadfiles");//Request对象获取绝对路径
            var filesArr = Directory.GetFiles(Server.MapPath("../Pages/uploadfiles"));//Server对象获取绝对路径
            var tempArr = filesArr[1].Split('\\');
            var jsdownLoadUrl = "../Pages/uploadfiles/" + tempArr[tempArr.Length - 1];
            var fileName = "图片下载";
            switch (btn.ID)
            {
                case "btn1":
                    getFile(filesArr[0], fileName);
                    break;
                case "btn2":
                    getFile1(filesArr[0], fileName);
                    break;
                case "btn3":
                    getFile2(filesArr[0], fileName);
                    break;
                case "btn4":
                    getFile3(jsdownLoadUrl);
                    break;
                case "btn5":
                    getFile4(filesArr[0], fileName);
                    break;
                default:
                    break;
            }

        }