Write text files without Byte Order Mark (BOM)?

问题:

I am trying to create a text file using VB.Net with UTF8 encoding, without BOM. Can anybody help me, how to do this?
I can write file with UTF8 encoding but, how to remove Byte Order Mark from it?

edit1: I have tried code like this;

    Dim utf8 As New UTF8Encoding()     Dim utf8EmitBOM As New UTF8Encoding(True)     Dim strW As New StreamWriter("c:\temp\bom\1.html", True, utf8EmitBOM)     strW.Write(utf8EmitBOM.GetPreamble())     strW.WriteLine("hi there")     strW.Close()          Dim strw2 As New StreamWriter("c:\temp\bom\2.html", True, utf8)         strw2.Write(utf8.GetPreamble())         strw2.WriteLine("hi there")         strw2.Close()

1.html get created with UTF8 encoding only and 2.html get created with ANSI encoding format.

Simplified approach - http://whatilearnttuday.blogspot.com/2011/10/write-text-files-without-byte-order.html

回答1:

In order to omit the byte order mark (BOM), your stream must use an instance of UTF8Encoding other than System.Text.Encoding.UTF8 (which is configured to generate a BOM). There are two easy ways to do this:

1. Explicitly specifying a suitable encoding:

1. Call the UTF8Encoding constructor with False for the encoderShouldEmitUTF8Identifier parameter.

2. Pass the UTF8Encoding instance to the stream constructor.

' VB.NET: Dim utf8WithoutBom As New System.Text.UTF8Encoding(False) Using sink As New StreamWriter("Foobar.txt", False, utf8WithoutBom)     sink.WriteLine("...") End Using

// C#: var utf8WithoutBom = new System.Text.UTF8Encoding(false); using (var sink = new StreamWriter("Foobar.txt", false, utf8WithoutBom)) {     sink.WriteLine("..."); }

2. Using the default encoding:

If you do not supply an Encoding to StreamWriter's constructor at all, StreamWriter will by default use an UTF8 encoding without BOM, so the following should work just as well:

' VB.NET: Using sink As New StreamWriter("Foobar.txt")     sink.WriteLine("...") End Using

// C#: using (var sink = new StreamWriter("Foobar.txt")) {     sink.WriteLine("..."); }

Finally, note that omitting the BOM is only permissible for UTF-8, not for UTF-16.

回答2:

Try this:

Encoding outputEnc = new UTF8Encoding(false); // create encoding with no BOM TextWriter file = new StreamWriter(filePath, false, outputEnc); // open file with encoding // write data here file.Close(); // save and close it

回答3:

Just Simply use the method WriteAllText from System.IO.File.

Please check the sample from File.WriteAllText.

This method uses UTF-8 encoding without a Byte-Order Mark (BOM), so using the GetPreamble method will return an empty byte array. If it is necessary to include a UTF-8 identifier, such as a byte order mark, at the beginning of a file, use the WriteAllText(String, String, Encoding) method overload with UTF8 encoding.

回答4:

Interesting note with respect to this: strangely, the static "CreateText()" method of the System.IO.File class creates UTF-8 files without BOM.

In general this the source of bugs, but in your case it could have been the simplest workaround :)

回答5:

If you do not specify an Encoding when creating a new StreamWriter the default Encoding object used is UTF-8 No BOM which is created via new UTF8Encoding(false, true).

So to create a text file without the BOM use of of the constructors that do not require you to provide an encoding:

new StreamWriter(Stream) new StreamWriter(String) new StreamWriter(String, Boolean)

回答6:

I think Roman Nikitin is right. The meaning of the constructor argument is flipped. False means no BOM and true means with BOM.

You get an ANSI encoding because a file without a BOM that does not contain non-ansi characters is exactly the same as an ANSI file. Try some special characters in you "hi there" string and you'll see the ANSI encoding change to without-BOM.

回答7:

XML Encoding UTF-8 without BOM
We need to submit XML data to the EPA and their application that takes our input requires UTF-8 without BOM. Oh yes, plain UTF-8 should be acceptable for everyone, but not for the EPA. The answer to doing this is in the above comments. Thank you Roman Nikitin.

Here is a C# snippet of the code for the XML encoding:

    Encoding utf8noBOM = new UTF8Encoding(false);       XmlWriterSettings settings = new XmlWriterSettings();       settings.Encoding = utf8noBOM;           …       using (XmlWriter xw = XmlWriter.Create(filePath, settings))       {           xDoc.WriteTo(xw);           xw.Flush();       }