java - 如何在java中创建utf-8编码的文件，以便在 Notepad++ /记事本或任何其他文本编辑器中打开时显示为UTF-8编码

Question

我尝试使用不同的阅读器使用java创建UTF-8文件。但是创建后，当我打开文件时，它不会被读取为UTF-8编码(我在 Notepad++ 中打开它，它是没有BOM的UTF-8 )。

File fileDir = new File("c:\\temp\\test.txt");

Writer out1 = new BufferedWriter(
    new OutputStreamWriter(
    new FileOutputStream(fileDir), 
    Charset.forName("UTF-8").newEncoder())
);

Writer out = new OutputStreamWriter(
    new FileOutputStream(fileDir), 
    Charset.forName("UTF-8")
);
out.append("Website UTF-8").append("\r\n");
out.append("?? UTF-8").append("\r\n");
out.append("??????? UTF-8").append("\r\n");

out.flush();
out.close();

Answer 1

您正确地以 UTF-8 编码写入文件。 (请注意，您没有使用 out1，而且没有必要)。

Notepad++ 告诉您该文件是“UTF-8 without BOM”。为什么你认为这不是 UTF-8？

BOM代表byte order mark 。它是一个特殊的 Unicode 字符，用于指示文件中的字节是采用小端顺序还是大端顺序。但对于UTF-8来说它没有任何意义，不推荐使用。来自维基百科文章:

The UTF-8 representation of the BOM is the byte sequence 0xEF,0xBB,0xBF. A text editor or web browser interpreting the text as ISO-8859-1 or CP1252 will display the characters  for this.

The Unicode Standard permits the BOM in UTF-8, but does not require nor recommend its use. Byte order has no meaning in UTF-8, so its only use in UTF-8 is to signal at the start that the text stream is encoded in UTF-8. The BOM may also appear when UTF-8 data is converted from other encodings that use a BOM.

是否有特殊原因需要包含 BOM？如果没有，那就不用担心。某些 Java XML 解析器无法正确处理 UTF-8 BOM，并且当您尝试解析以 UTF-8 编码且以 BOM 开头的 XML 文档时，会出现错误。