如何正确保存和打开文件（不破坏文件） [英] How to save and open files correctly ( without destroying file )

问题描述

这是我的代码：

this is my code :

private void BtnDisplay_Click(object sender, EventArgs e)
        {
            if (GridFile.CurrentCell == null)
            {
                MessageBox.Show("select a row");
                return;
            }
            DataTable dt = new DataTable();
            int SelectedRow = GridFile.CurrentCell.RowIndex;
            string OriginalPath = GridFile.SelectedRows[0].Cells[2].Value.ToString();
            string tempsafefilename = GridFile.SelectedRows[0].Cells[5].Value.ToString();
            saveFileDialog1.FileName = OriginalPath;
            string FileName = saveFileDialog1.FileName;
            //.......
            if (File.Exists(FileName))
            {
                Process.Start(FileName);
            }
            else
            {
 
byte[] FileData = new byte[32768];
               FileData = (byte[])DS.Tables["TeacherFile"].Rows[SelectedRow]["FileData"];
                String newfile = @"D:\Temp";
                DirectoryInfo l_dDirInfo = new DirectoryInfo(newfile);
                if (l_dDirInfo.Exists == false)
                {
                    Directory.CreateDirectory(newfile);
                }
 
                string NewPath = newfile + "\\" + tempsafefilename;
 

                    //FileStream fStream = new FileStream(NewPath, FileMode.Create);
 
                    //while (fStream.Read(FileData, 0, FileData.Length) > 0)
                    //{
                    //    Process.Start(NewPath);
                    //}
                   
                    using (FileStream fStream = new FileStream(NewPath, FileMode.Create))
                    {
                        fStream.Write(FileData, 0, FileData.Length);
                        FileData = ReadToEnd(fStream);
                        fStream.Write(FileData, 0, FileData.Length);
                        Process.Start(NewPath);
                    }
 
 public static byte[] ReadToEnd(System.IO.Stream stream)
        {
            long originalPosition = 0;
 
            if (stream.CanSeek)
            {
                originalPosition = stream.Position;
                stream.Position = 0;
            }
 
            try
            {
                byte[] readBuffer = new byte[4096];
 
                int totalBytesRead = 0;
                int bytesRead;
 
                while ((bytesRead = stream.Read(readBuffer, totalBytesRead, readBuffer.Length - totalBytesRead)) > 0)
                {
                    totalBytesRead += bytesRead;
 
                    if (totalBytesRead == readBuffer.Length)
                    {
                        int nextByte = stream.ReadByte();
                        if (nextByte != -1)
                        {
                            byte[] temp = new byte[readBuffer.Length * 2];
                            Buffer.BlockCopy(readBuffer, 0, temp, 0, readBuffer.Length);
                            Buffer.SetByte(temp, totalBytesRead, (byte)nextByte);
                            readBuffer = temp;
                            totalBytesRead++;
                        }
                    }
                }
 

                byte[] buffer = readBuffer;
                if (readBuffer.Length != totalBytesRead)
                {
                    buffer = new byte[totalBytesRead];
                    Buffer.BlockCopy(readBuffer, 0, buffer, 0, totalBytesRead);
                }
                return buffer;
            }
            finally
            {
                if (stream.CanSeek)
                {
                    stream.Position = originalPosition;
                }
            }
        }
        //....OKKKKKK
        byte[] ReadFile(string sPath)
        {
 

            FileStream fStream = new FileStream(sPath, FileMode.Open, FileAccess.Read);
            byte[] buffer = new byte[32768];
            int read = 0;
            int chunk;
            fStream.Position = 3147483648;
            while ((chunk = fStream.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 = fStream.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;
        }

我的程序所做的是将文件（任何文件 - 电影 - 音乐 - zip ...）转换为代码（0和1） - 我想）并将其保存到我的SQL数据库中。现在，当我点击（打开文件 - 显示）按钮时，它会显示文件，但文件已被销毁。下面的链接是veronica movie的图片（大约700 MB）我用我的软件保存它，当我点击打开时，我的软件打开了文件，但它已损坏，KMPlayer向我显示这些代码。怎么解决？请帮帮我。



https://i.imgsafe.org/ f52cc7409c.png [ ^ ]



我尝试了什么：



i我的旧代码在这里：



http://snipsave.com/user/profile/johnnyflow#14098

what my program does, is that convert a file (any file- movie - music - zip...) to the codes (0 and 1 - I think) and save it to my SQL database. now when I click on (open file - show) button it show me the file but the file is destroyed. the below link is a picture of "veronica movie" ( it's about 700 MB) I save it with my software and when I clicked on open, my software opened the file but it was corrupted and the KMPlayer show me those codes. how to fix it? please help me.

https://i.imgsafe.org/f52cc7409c.png[^]

What I have tried:

i put my old codes here :

http://snipsave.com/user/profile/johnnyflow#14098

推荐答案

你很可能不是'保存数据库中的正确数据，或者您没有检索它并再次正确保存它。

在SQL中保存文件的最简单方法是将其直接加载到字节数组中，保存：

The chances are that you aren't saving the right data in the DB, or you aren't retrieving it and saving it again properly.
The easiest way to save a file in SQL is to load it directly into a byte array, and save that:

byte[] data = File.readAllBytes(pathToFile);

将字节写回文件也很简单：

And to write the bytes back to a file is also trivial:

File.WriteAllBytes(pathToFile, data);

这里有关于如何保存和检索数据的信息：为什么我得到参数无效。我从数据库中读取图像时出现异常？ [ ^ ] - 它基于图像，但视频数据的原理完全相同。



但是......我不会将视频数据存储在数据库中：它是大数据，它会导致系统出现很多瓶颈以保存和检索它。

相反，将视频存储为文件并将文件位置存储在数据库中。

我这样做的方法是使用File将文件复制到带有Guid文件名的已知位置。复制然后将基于Guid的路径加上原始文件名存储在数据库中。

然后，您可以使用File.Copy重新创建原始文件，以便在需要时将其重新放回。

There is info on how to save and retrieve it to the DB here: Why do I get a "Parameter is not valid." exception when I read an image from my database?[^] - it's based aroung images, but the principles are exactly the same for video data.

But...I wouldn't store video data in a database: it's big data and it will cause a lot of bottlenecks on your system to save and retrieve it.
Instead, store the video as a file and store the file location in the DB.
The way I'd do it is to copy the file to a "known" location with a Guid filename using File.Copy and then store the Guid-based path plus the original file name in the DB.
You can then recreate the original by using File.Copy to put it back when needed.

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