即使字符串爲UTF-8，電子郵件主題也會設置爲CP1252編碼

Question

文件new1.txt包含作爲主題發送的UTF-8字符串。但收到的電子郵件將顯示CP1252格式的字符串。但是，如果我通過運行配置 - >常用選項卡並將控制檯編碼設置爲UTF-8來設置控制檯編碼，則可以在收到的電子郵件中正確查看UTF-string。我使用谷歌服務器爲這個測試：

不工作： ℃〜¥æœ¬：合作伙伴名稱：？？ã，¢ã,¹ãƒãƒ©ã,¼ãƒã，«æªå¼ä¼šç¤¾：

工作： 日本：合作伙伴名稱：アストラゼネカ株式會社

我的代碼： final String username =「xxxxx@gmail.com」; final String password =「xxxxxx」;

Properties props = new Properties(); 
    props.put("mail.smtp.host", "smtp.gmail.com"); 
    props.put("mail.smtp.socketFactory.port", "465"); 
    props.put("mail.smtp.socketFactory.class", 
      "javax.net.ssl.SSLSocketFactory"); 
    props.put("mail.smtp.auth", "true"); 
    props.put("mail.smtp.port", "465"); 

    Session session = Session.getInstance(props, 
     new javax.mail.Authenticator() { 
      protected PasswordAuthentication getPasswordAuthentication() { 
       return new PasswordAuthentication(username,password); 
      } 
     }); 

    try { 
     File fileDir = new File("c:\\new1.txt"); 

     BufferedReader in = new BufferedReader(
      new InputStreamReader(
         new FileInputStream(fileDir), "UTF-8")); 

     String str; 
     String str1 =""; 

     while ((str = in.readLine()) != null) { 
      str1 += str; 
     } 

     Message message = new MimeMessage(session); 
     MimeMultipart mp = new MimeMultipart(); 
     message.setFrom(new InternetAddress("xxxxx@gmail.com")); 
     message.setRecipients(Message.RecipientType.TO, 
      InternetAddress.parse("xxxx@xxxxx.com")); 
     message.setSubject(str1); 
     MimeBodyPart body = new MimeBodyPart(); 
     body.setContent("This is a Test EMail. Please ignore", "text/html"); 
     body.setDisposition(MimeBodyPart.INLINE); 
     mp.addBodyPart(body); 
     byte[] attachmentData = str1.getBytes(); 
     DataHandler dh = new DataHandler(new ByteArrayDataSource(attachmentData,"application/octet-stream")); 
     MimeBodyPart attachment = new MimeBodyPart(); 
     attachment.setDataHandler(dh); 
     attachment.setDisposition(MimeBodyPart.ATTACHMENT); 
     attachment.setFileName("new1.txt"); 
     mp.addBodyPart(attachment); 

     message.setContent(mp); 
     Transport.send(message); 

     System.out.println("Done"); 

感謝 馬杜

以下是我在J2EE應用程序所做的代碼更改。在這裏它添加3個文件作爲附件。 3個文件之一是主題本身。在附件（Subject.txt）中，conent很好。

MimeMessage message = new MimeMessage(s); 

    .... 

    message.setSubject(subject,"UTF-8");// MimeUtility.encodeText(subject,"UTF-8", "B")); 

    ... 

      MimeBodyPart body = new MimeBodyPart(); 
      body.setContent(sm.getMailBody(), "text/html; charset=UTF-8"); 
      body.setDisposition(MimeBodyPart.INLINE); 
      mp.addBodyPart(body); 

The debug message. I could not add it as text

Answer 1

除需要使用MimeUtility.encodeText()進行編碼。

但是正如Bill Shannon所指出的那樣：不要通過手動編碼來代替它，請調用MimeMessage.setSubject(String subject, String charset)。否則，setSubject將在內部對產生的字符串進行平臺編碼，這可能會導致麻煩。

一件事：

byte[] attachmentData = str1.getBytes(); 

檢索字節平臺編碼 - 這可能不是UTF-8。嘗試

byte[] attachmentData = str1.getBytes(Charset.forName("utf-8")); 

Answer 2

聲明消息是MimeMessage，然後使用setSubject method that allows you to specify the charset。