RFC822 电子邮件 - 格式化程序 - Android/iOS - 创建没有会话或主机的 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RFC822之后的那个字段，但是我找不到它。

我需要什么？

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

我尝试了什么？

问题是它们是面向会话的，我没有凭据或主机。

更新

我需要 this 之类的东西，但我想要 String dataRFC822 = message.getRFC822String();

之类的东西，而不是使用 message.writeTo(...)

// 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

您可以使用 ByteArrayOutputStream，它是 OutputStream 的一个实现，它写入 byte 数组。您可以创建一个实例并将其传递给您方法上的 writeTo(OutputStream)，然后从那里调用 ByteArrayOutputStream 上的 toString 以检索消息的 String 表示。

ByteArrayOutputStream out = new ByteArrayOutputStream();
message.writeto(out);
String s = out.toString();

Answer 2

您可以手动制作一个 RFC822 兼容字符串，如果您不附加文件或绝对需要多部分 mime 消息，则更简单：

String makeRfc822email(String from, String to, String subject, String message) {
  StringBuilder builder = new StringBuilder();
  builder.append("From: ");
  builder.append(from);
  builder.append("\n");

  builder.append("To: ");
  builder.append(to);
  builder.append("\n");

  builder.append("Subject: ");
  builder.append(subject);
  builder.append("\n\n");  // Blank line before message.

  builder.append(message);

  return builder.toString();
}

Answer 3

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

诀窍是您不需要会话对象的凭据，只要您不真正使用它连接到服务器即可。然后我就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--

RFC822 电子邮件 - 格式化程序 - Android/iOS - 创建没有会话或主机的 MimeMessage

RFC822 email - Formatter - Android/iOS - create MimeMessage without session or host

java

android

objective-c

email

rfc822

我需要什么？

我尝试了什么？

更新