java - 将字符串转换为 javax 邮件消息对象

Question

我正在尝试从邮件字符串中获取附件。我认为最好的方法是获取原始字符串，将其转换为 javax 邮件消息，然后按照 this 进行操作。教程。我找不到一种方法来获取原始字符串并将其转换为 javax 邮件消息。附件部分的长度要长得多，但为了简单起见，我把它剪短了。

示例字符串:

X-DateCreated: 7/11/2014 8:12:53 PM (UTC)
X-Received: Secure delivery via Web Service
Thread-Topic: Test attachment
Date: Fri, 11 Jul 2014 16:12:53 -0400
Message-ID: <218685@CM>
thread-index: Ac+hJI371nbUghSdS9eoy8ESMrck3w==
From: <---->
To: <---->
Subject: Test attachment
MIME-Version: 1.0
Content-Type: multipart/mixed;
    boundary="----=_NextPart_000_55BE_01CFA103.0703D820"
Content-Class: urn:content-classes:message
Importance: normal
Priority: normal
X-MimeOLE: Produced By Microsoft MimeOLE V6.2.9200.16384

This is a multi-part message in MIME format.

------=_NextPart_000_55BE_01CFA103.0703D820
Content-Type: text/plain
Content-Transfer-Encoding: 7bit

Test attachment.
------=_NextPart_000_55BE_01CFA103.0703D820
Content-Type: application/octet-stream;
    name="Copyright.docx"
Content-Transfer-Encoding: base64
Content-Disposition: attachment;
    filename="Copyright.docx"
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AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAArJLBasMwDEDvg/2D0b1R2sEYo04v
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AAAhADsvItvGAQAAHgsAABwACAF3b3JkL19yZWxzL2RvY3VtZW50LnhtbC5yZWxzIKIEASigAAEA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAvJXBbtswDIbvBfoOhu6V4rRJtyFOL2uBHnZZU2BX
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Answer 1

好吧，经过一段时间和迈克的回答，我想出了这个解决方案。下面的代码将获取一个字符串，将其转换为 javax Message 对象，然后解析它以提取各种字段并显示它们。希望这对其他人也有帮助!

代码:

try {
    InputStream is = new ByteArrayInputStream(receivedMessage.getBytes(StandardCharsets.UTF_8));
    MimeMessage mime = new MimeMessage(null, is);
    String finalMessage = "From: " + mime.getFrom()[0].toString() + "\n"
    + "To: " + mime.getRecipients(RecipientType.TO)[0] + "\n";
    for (int i = 1; i < mime.getRecipients(RecipientType.TO).length;i++)
        finalMessage = finalMessage + mime.getRecipients(RecipientType.TO)[i] + "\n";
    if (mime.getRecipients(RecipientType.CC) != null && mime.getRecipients(RecipientType.CC).length != 0) {
        finalMessage = finalMessage + "CC: " + mime.getRecipients(RecipientType.CC)[0] + "\n";
        for (int i = 1; i < mime.getRecipients(RecipientType.CC).length;i++)
            finalMessage = finalMessage + mime.getRecipients(RecipientType.CC)[i] + "\n";
    }
    if (mime.getRecipients(RecipientType.BCC)!= null && mime.getRecipients(RecipientType.BCC).length != 0) {
        finalMessage = finalMessage + "BCC: " + mime.getRecipients(RecipientType.BCC)[0] + "\n";
        for (int i = 1; i < mime.getRecipients(RecipientType.BCC).length;i++)
            finalMessage = finalMessage + mime.getRecipients(RecipientType.BCC)[i] + "\n";
    }
    finalMessage = finalMessage + "Subject: " + mime.getSubject() + "\n"
    + "Sent: " + mime.getSentDate() + "\n";
    if (mime.getReceivedDate() != null)
        finalMessage = finalMessage + "Received: " + mime.getReceivedDate() + "\n\n";
    else
        finalMessage = finalMessage + "\n";

    // suppose 'message' is an object of type Message
    String contentType = mime.getContentType();

    if (contentType.contains("multipart")) {
        // this message may contain attachment
        Multipart multiPart = (Multipart) mime.getContent();

        String attachments = "";
        String messageContent = "";

        for (int i = 0; i < multiPart.getCount(); i++) {
            MimeBodyPart part = (MimeBodyPart) multiPart.getBodyPart(i);
            if (Part.ATTACHMENT.equalsIgnoreCase(part.getDisposition())) {
                // this part is attachment
                // code to save attachment...
                attachments = attachments + "Attachment: "+part.getFileName()+"\n"; //Turn this into a link the user can click to download
            }
            else {
                messageContent = messageContent + part.getContent().toString() + "\n";
            }
        }
        finalMessage = finalMessage + messageContent + "\n" + attachments;
    }
    message.setText(finalMessage);
} catch (Exception e4) {
    e4.printStackTrace();
}