java - RFC822 电子邮件 - Formatter - Android/iOS - 创建没有 session 或主机的 MimeMessage

Question

我有以下电子邮件:

Subject = Hello!
Body = Bla bla bla bla.
Recipients = "carlos@mail.com", "mike@mail.com"

现在我想解析遵循 RFC822 的那些字段，但找不到它。

我需要什么？

所有字段(主题、正文、收件人)-> 格式化程序(java 和/或 objective-c)-> 根据 RC822 的字符串

我尝试了什么？

• > https://code.google.com/archive/p/javamail-android/
• mime4j

问题是它们是面向 session 的，我没有凭据或主机。

更新

我需要像 this 这样的东西但不是使用 message.writeTo(...) 我想要类似 String dataRFC822 = message.getRFC822String();

// Recipient's email ID needs to be mentioned.
      String to = "destinationemail@gmail.com";

      // Sender's email ID needs to be mentioned
      String from = "fromemail@gmail.com";

      // Get the Session object. Which I have not and I don't want it.
      Session session = Session.getInstance(props,
         new javax.mail.Authenticator() {
            protected PasswordAuthentication getPasswordAuthentication() {
               return new PasswordAuthentication(username, password);
            }
         });

      try {
         // Create a default MimeMessage object.
         Message message = new MimeMessage(session);

         // Set From: header field of the header.
         message.setFrom(new InternetAddress(from));

         // Set To: header field of the header.
         message.setRecipients(Message.RecipientType.TO,
            InternetAddress.parse(to));

         // Set Subject: header field
         message.setSubject("Testing Subject");

         // Create the message part
         BodyPart messageBodyPart = new MimeBodyPart();

         // Now set the actual message
         messageBodyPart.setText("This is message body");

         // Create a multipar message
         Multipart multipart = new MimeMultipart();

         // Set text message part
         multipart.addBodyPart(messageBodyPart);

         // Part two is attachment
         messageBodyPart = new MimeBodyPart();
         String filename = "/home/manisha/file.txt";
         DataSource source = new FileDataSource(filename);
         messageBodyPart.setDataHandler(new DataHandler(source));
         messageBodyPart.setFileName(filename);
         multipart.addBodyPart(messageBodyPart);

         // Send the complete message parts
         message.setContent(multipart);

         //instead write it on a stream i I want get back the string formated according to rfc822
         message.writeTo(...);


      } catch (MessagingException e) {
         throw new RuntimeException(e);
      }

Answer 1

正如@Shadowfacts 所指出的，您可以使用 ByteArrayOutputStream。

诀窍是您不需要 session 对象的凭据，只要您不真正使用它来连接服务器即可。然后我只是重新使用了你的大部分代码:

String to = "destinationemail@gmail.com";
String from = "fromemail@gmail.com";

// Empty properties and null credentials makes a valid session.
Properties props = new Properties();
Session session = Session.getInstance(props, null);

Message message = new MimeMessage(session);
message.setFrom(new InternetAddress(from));
message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(to));
message.setSubject("Testing Subject");
BodyPart messageBodyPart = new MimeBodyPart();
messageBodyPart.setText("This is message body");

Multipart multipart = new MimeMultipart();
multipart.addBodyPart(messageBodyPart);

messageBodyPart = new MimeBodyPart();
String filename = "/etc/hostname";
DataSource source = new FileDataSource(filename);
messageBodyPart.setDataHandler(new DataHandler(source));
messageBodyPart.setFileName(filename);
multipart.addBodyPart(messageBodyPart);

message.setContent(multipart);

ByteArrayOutputStream baos = new ByteArrayOutputStream();
message.writeTo(baos);
String rfc822message = baos.toString();
System.out.print(rfc822message);

我得到的结果:

From: fromemail@gmail.com
To: destinationemail@gmail.com
Message-ID: <392292416.1.1481815905219@nitoshpas>
Subject: Testing Subject
MIME-Version: 1.0
Content-Type: multipart/mixed; 
boundary="----=_Part_0_59559151.1481815905197"

------=_Part_0_59559151.1481815905197
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit

This is message body
------=_Part_0_59559151.1481815905197
Content-Type: application/octet-stream; name="/etc/hostname"
Content-Transfer-Encoding: 7bit
Content-Disposition: attachment; filename="/etc/hostname"

nitoshpas

------=_Part_0_59559151.1481815905197--