将附件内容流写入光盘上的文件时跳过前导字节 [英] Skip Leading Bytes When Writing Attachment Content Stream To File On The Disc

问题描述

大家好，

我在将附件内容流保存到文件时遇到问题，问题是保存的文件包含前导字节，特别是在我的情况下有三个问号??? 。

问题似乎很简单，但我不确定它背后是什么，是写入文件的BOM（字节顺序标记）还是流的前缀长度？

我尝试了几种方法，但是所有方法都有相同的结果：

这是我用过的方法：

第一个：

  public   void  saveAttachment（System.Net.Mail.Attachment attachment）
 {
 StreamReader reader =  new  StreamReader（attachment.ContentStream）; 
 File.WriteAllText（attachment.Name，reader.ReadToEnd（））; 
} 

第二个（类似于第一个）：

  public   void  saveAttachment（System.Net.Mail.Attachment attachment）
 {
 StreamWriter writer =  new  StreamWriter（attachment.Name）; 
 StreamReader reader =  new  StreamReader（attachment.ContentStream）; 
 writer.Write（reader.ReadToEnd（））; 
 writer.Close（）; 
} 

基于 link ：

  public   void  saveMailAttachment（System.Net.Mail.Attachment attachment）
 {
  byte  [] allBytes =  new   byte  [attachment.ContentStream.Length]; 
 
  int  bytesRead = attachment.ContentStream.Read（allBytes， 0 ，（  int ）attachment.ContentStream.Length）; 
 
  string  destinationFile = attachment.Name; 
 
 BinaryWriter writer =  new  BinaryWriter（ new  FileStream（destinationFile，FileMode.OpenOrCreate ，FileAccess.Write，FileShare.None））; 
 writer.Write（allBytes）; 
 writer.Close（）; 
} 

我试过玩字节数组，但我不认为这是解决问题的一种非常可靠的方法，非常感谢任何帮助。

提前谢谢。

解决方案

如果你总是有3，正好3个文件开头的标记字符，根据你的第二个实现，有一个非常简单的方法来实现它：

  public   void  saveAttachment（System.Net.Mail.Attachment attachment）
 {
 使用（ var  writer =  new  StreamWriter（attachment.Name））
 {
 使用（ var  reader =  new  StreamReader（attachment.ContentStream））
 {
  //  设置流指针 
 reader.BaseStream.Seek（ 3 ，SeekOrigin.Begin）; 
 writer.Write（reader.Read（））; 
 writer.Close（）; 
} 
} 
} 

免费配置逻辑。 ：）

Hi all,
I'm facing a problem with saving attachment content stream to a file, the problem is that the saved files contains leading bytes, specifically in my case three question marks ??? .
The problem seems simple but i'm not sure what is behind it , is it BOM (Byte Order Mark) written to the file or is it prefix length of the stream ?
I've tried several ways , but with all had the same results:
Here is my used methods:
First one:

public void saveAttachment(System.Net.Mail.Attachment attachment)
        {
            StreamReader reader = new StreamReader(attachment.ContentStream);
            File.WriteAllText(attachment.Name, reader.ReadToEnd());
        }

Second one (similar to the first):

public void saveAttachment(System.Net.Mail.Attachment attachment)
        {
            StreamWriter writer = new StreamWriter(attachment.Name);
            StreamReader reader = new StreamReader(attachment.ContentStream);
            writer.Write(reader.ReadToEnd());
            writer.Close();
        }

Third method based on the link :

public void saveMailAttachment(System.Net.Mail.Attachment attachment)
{
    byte[] allBytes = new byte[attachment.ContentStream.Length];

    int bytesRead = attachment.ContentStream.Read(allBytes, 0, (int)attachment.ContentStream.Length);

    string destinationFile = attachment.Name;

    BinaryWriter writer = new BinaryWriter(new FileStream(destinationFile, FileMode.OpenOrCreate, FileAccess.Write, FileShare.None));
    writer.Write(allBytes);
    writer.Close();
}

I tried playing with the bytes array , but i don't think it's a very reliable way to solve the problem , any help would be very appreciated.
Thanks in advance.

解决方案

If you always have 3, and exactly 3, marker characters at the start of the file, there's a very easy way to implement this based on your second implementation:

public void saveAttachment(System.Net.Mail.Attachment attachment)
{
    using(var writer = new StreamWriter(attachment.Name))
    {
        using(var reader = new StreamReader(attachment.ContentStream))
        {
            // Set the stream pointer
            reader.BaseStream.Seek(3, SeekOrigin.Begin);
            writer.Write(reader.Read());
            writer.Close();
        }
    }
}

Dispose logic included free of charge. :)

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