如何上传文件并将其保存到使用C＃进一步preVIEW一个流？ [英] How can I upload a file and save it to a Stream for further preview using C#?
问题描述
有没有上传文件，将其保存到一个流的方式，此流我会暂时保存在一个会话，并在最后，我会尽量preVIEW这个上传的文件就是在这个会议？ ？
Is there a way to upload a file, save it to a Stream, this Stream I will save it temporarily in a Session and, at last, I will try to preview this uploaded file that is in this Session??
例如，一个PDF文件。
For example, a pdf file.
谢谢！
EDITED
下面就是我想要做的：
HttpPostedFileBase hpf = Request.Files[0] as HttpPostedFileBase;
byte[] buffer = new byte[hpf.InputStream.Length];
MemoryStream ms = new MemoryStream(buffer);
ms.Read(buffer, 0, (int)ms.Length);
Session["pdf"] = ms.ToArray();
ms.Close();
而在另一种方法，我这样做是：
And in another method, I'm doing this:
byte[] imageByte = null;
imageByte = (byte[])Session["pdf"];
Response.ContentType = "application/pdf";
Response.Buffer = true;
Response.Clear();
Response.BinaryWrite(imageByte);
但没有happends ......我的浏览器，甚至打开一个页面NEM显示PDF文件，但表示说，该文件是不是PDF（或类似文件不与PDF发起一个窗口，我没T理解）
But nothing happends... my browser even opens a nem page to show the pdf file, but a window is shown saying that the file is not a pdf (or something like the file doesn't initiate with pdf, I didn't understand that)
推荐答案
当然是。我上传我的应用文件（PDF /图片）到我的分贝。我的模型对象实际存储文件的字节数组，但其他功能我不得不转换和从视频流，以便即时确定它一样容易保持在流格式。
Sure is. I upload files (PDF/images) to my db in my app. My model object actually stores the file as a byte array but for other functions i have to convert to and from streams so im sure its just as easy to keep it in stream format.
下面是一些code例子（复制粘贴ñ）从我的应用程序 -
Here are some code examples (copy n paste) from my app-
的文件，我用它来移动文件（PDF文件/图片）对象周围：
public class File : CustomValidation, IModelBusinessObject
{
public int ID { get; set; }
public string MimeType { get; set; }
public byte[] Data { get; set; }
public int Length { get; set; }
public string MD5Hash { get; set; }
public string UploadFileName { get; set; }
}
..在 PdfDoc 专为PDF文件类型：
..the PdfDoc type specifically for PDF files:
public class PdfDoc : File
{
public int ID { get; set; }
public int FileID
{
get { return base.ID; }
set { base.ID = value; }
}
[StringLength(200, ErrorMessage = "The Link Text must not be longer than 200 characters")]
public string LinkText { get; set; }
public PdfDoc() { }
public PdfDoc(File file)
{
MimeType = file.MimeType;
Data = file.Data;
Length = file.Length;
MD5Hash = file.MD5Hash;
UploadFileName = file.UploadFileName;
}
public PdfDoc(File file, string linkText)
{
MimeType = file.MimeType;
Data = file.Data;
Length = file.Length;
MD5Hash = file.MD5Hash;
UploadFileName = file.UploadFileName;
LinkText = linkText;
}
}
..接收文件上传多部分POST动作的例子：
.. an example of an action that receives multi-part POST for file uploading:
//
// POST: /Announcements/UploadPdfToAnnouncement/ID
[KsisAuthorize(Roles = "Admin, Announcements")]
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult UploadPdfToAnnouncement(int ID)
{
FileManagerController.FileUploadResultDTO files =
FileManagerController.GetFilesFromRequest((HttpContextWrapper)HttpContext);
if (String.IsNullOrEmpty(files.ErrorMessage) && files.TotalBytes > 0)
{
// add SINGLE file to the announcement
try
{
this._svc.AddAnnouncementPdfDoc(
this._svc.GetAnnouncementByID(ID),
new PdfDoc(files.Files[0]),
new User() { UserName = User.Identity.Name });
}
catch (ServiceExceptions.KsisServiceException ex)
{
// only handle our exceptions
base.AddErrorMessageLine(ex.Message);
}
}
// redirect back to detail page
return RedirectToAction("Detail", "Announcements", new { id = ID });
}
现在你可以看到我将文件对象传递给我的服务在这里，但你可以选择将其添加到会话，并传递一个id回例如preVIEW视图。
Now you can see i pass the file object to my service here but you can choose to add it to the session and pass an id back to the 'preview' view for example.
最后，这里是一个通用的动作我用它来呈现出来的文件给客户端（你可以有类似的东西呈现文件从会话/流）：
Finally, here is a generic action i use to render files out to the client (you could have something similar render the files/stream from the Session):
//
// GET: /FileManager/GetFile/ID
[OutputCache(Order = 2, Duration = 600, VaryByParam = "ID")]
public ActionResult GetFile(int ID)
{
FileService svc = ObjectFactory.GetInstance<FileService>();
KsisOnline.Data.File result = svc.GetFileByID(ID);
return File(result.Data, result.MimeType, result.UploadFileName);
}
编辑：结果
我发现我需要更多的样本来解释上面 -
I noticed i need more samples to explain the above-
对于上面的上传动作， FileUploadResultDTO 类：
For the upload action above, the FileUploadResultDTO class:
public class FileUploadResultDTO
{
public List<File> Files { get; set; }
public Int32 TotalBytes { get; set; }
public string ErrorMessage { get; set; }
}
以及 GetFilesFromRequest 功能：
public static FileUploadResultDTO GetFilesFromRequest(HttpContextWrapper contextWrapper)
{
FileUploadResultDTO result = new FileUploadResultDTO();
result.Files = new List<File>();
foreach (string file in contextWrapper.Request.Files)
{
HttpPostedFileBase hpf = contextWrapper.Request.Files[file] as HttpPostedFileBase;
if (hpf.ContentLength > 0)
{
File tempFile = new File()
{
UploadFileName = Regex.Match(hpf.FileName, @"(/|\\)?(?<fileName>[^(/|\\)]+)$").Groups["fileName"].ToString(), // to trim off whole path from browsers like IE
MimeType = hpf.ContentType,
Data = FileService.ReadFully(hpf.InputStream, 0),
Length = (int)hpf.InputStream.Length
};
result.Files.Add(tempFile);
result.TotalBytes += tempFile.Length;
}
}
return result;
}
最后（我希望我现在需要的一切）这个的readFully 功能。这不是我的设计。我是从网上 - 流读取可能会非常棘手。我觉得这个功能是完全读取流最成功的方式：
And finally (i hope i have everything you need now) this ReadFully function. It's not my design. I got it from the net - stream reading can be tricky. I find this function is the most successful way to completely read a stream:
/// <summary>
/// Reads data from a stream until the end is reached. The
/// data is returned as a byte array. An IOException is
/// thrown if any of the underlying IO calls fail.
/// </summary>
/// <param name="stream">The stream to read data from</param>
/// <param name="initialLength">The initial buffer length</param>
public static byte[] ReadFully(System.IO.Stream stream, long initialLength)
{
// reset pointer just in case
stream.Seek(0, System.IO.SeekOrigin.Begin);
// If we've been passed an unhelpful initial length, just
// use 32K.
if (initialLength < 1)
{
initialLength = 32768;
}
byte[] buffer = new byte[initialLength];
int read = 0;
int chunk;
while ((chunk = stream.Read(buffer, read, buffer.Length - read)) > 0)
{
read += chunk;
// If we've reached the end of our buffer, check to see if there's
// any more information
if (read == buffer.Length)
{
int nextByte = stream.ReadByte();
// End of stream? If so, we're done
if (nextByte == -1)
{
return buffer;
}
// Nope. Resize the buffer, put in the byte we've just
// read, and continue
byte[] newBuffer = new byte[buffer.Length * 2];
Array.Copy(buffer, newBuffer, buffer.Length);
newBuffer[read] = (byte)nextByte;
buffer = newBuffer;
read++;
}
}
// Buffer is now too big. Shrink it.
byte[] ret = new byte[read];
Array.Copy(buffer, ret, read);
return ret;
}
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