文本文件编码为UTF_8？ [英] Text file encoding to UTF_8?

问题描述

我正在编写一个发送电子邮件附件的Java项目。




在我的测试用例中，我添加了一些日语单词一些Hiraganas和Katakanas到我附加的testfile.txt（我以UTF-8编码保存。 ）




但是当我发送测试邮件给自己时，在打开附件testfile.txt之后，每个日语Chars都变成????

所以我只是想知道为什么会发生这种情况？

谢谢

Allan

PS更具体来说，这里是我的代码。
我正在使用mail.jar发送电子邮件。

这是我如何获取文件：

  / ** 
 *向电子邮件添加附件。 
 * @param filePath 
 * / 
 public void setFile（String filePath）{
 
 attachment = new File（filePath）; 
 
} 
  

以下是我将文件附加到我的MIME邮箱中部分。

  / *如果给出附件，请添加附件。* / 
 if（attachment！= null）{ 
 MimeBodyPart attachmentPart = new MimeBodyPart（）; 
 attachmentPart.attachFile（attachment）; 
 multipart.addBodyPart（attachmentPart）; 
} 
  

解决方案

你需要确保你'使用适当的字符集读取和写入文件。

因此不是这样，这将使用平台的默认字符集：

  Reader reader = new FileReader（/ testfile.txt）; 
 // ... 
  

但更重要的是，使用 InputStreamReader 其中明确指定正确的字符集：

  Reader reader = new InputStreamReader（new FileInputStream（/ testfile.txt），UTF- 8\" ）; 
 // ... 
  

另外，在 Content-键入您必须设置字符集属性的电子邮件附件的标题，您必须使用UTF-8写出附件。由于您使用的邮件API不清楚，因此无法给出更多详细信息。或者，您也可以坚持使用 InputStream / OutputStream ，因为将流内容作为纯字节，因此将不要影响字节代表的字符集。

---

更新：您正在使用Javamail的< a href =http://download.oracle.com/javaee/6/api/javax/mail/internet/MimeBodyPart.html =nofollow> MimeBodyPart ，而不显式指定具有charset属性的内容类型。现在，您依赖邮件客户端是否将内容视为UTF-8。修正如下：

  MimeBodyPart attachmentPart = new MimeBodyPart（）; 
 attachmentPart.attachFile（attachment）; 
 attachmentPart.setHeader（Content-Type，text / plain; charset = utf-8）; 
 multipart.addBodyPart（attachmentPart）; 
  

I'm writing a Java project sending email with attachment.

In my test case, I add some Japanese words "some Hiraganas and Katakanas" to my attached testfile.txt (which I saved in UTF-8 encoding.)

But when I send my test email to myself, after I opened the attached testfile.txt, every Japanese Chars turns to be "????".

So I'm just wondering why this happens...?

Thank you

Allan

P.S. to be more specific, here is my code. I am using mail.jar to send email.

Here is how I get the file:

/**
 * Add an attachment to the Email.
 * @param filePath
 */
public void setFile(String filePath){

    attachment = new File(filePath);

}

and below is how I attach the file into my MIME email part.

/*Add attachment if an attachment is given.*/
    if(attachment != null){
    MimeBodyPart attachmentPart = new MimeBodyPart();
    attachmentPart.attachFile(attachment);
    multipart.addBodyPart(attachmentPart);
    }

解决方案

You need to ensure that you're reading and writing the file using the proper charset.

I.e. thus not so, which would use platform's default charset:

Reader reader = new FileReader("/testfile.txt");
// ...

But more so, using InputStreamReader wherein you explicitly specify the proper charset:

Reader reader = new InputStreamReader(new FileInputStream("/testfile.txt"), "UTF-8");
// ...

Also, in the Content-Type header of the email attachment you have to set the charset attribute and you have to write out the attachment using UTF-8. Further detail can't be given as it's unclear what mail API you're using. Alternatively, you can also stick to using InputStream/OutputStream only as that would stream the content as pure bytes and thus wouldn't affect the charset the bytes represent.

---

Update: you're using Javamail's MimeBodyPart without explicitly specifying the content type with the charset attribute. Now you're dependent on the mail client whether it treats the content as UTF-8 or not. Fix it as follows:

MimeBodyPart attachmentPart = new MimeBodyPart();
attachmentPart.attachFile(attachment);
attachmentPart.setHeader("Content-Type", "text/plain;charset=utf-8");
multipart.addBodyPart(attachmentPart);

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