Java

Get the Content-ID of an Attachment

Demonstrates the Chilkat Email.GetAttachmentContentID method, which returns the Content-ID header field for the Nth attachment. The index is zero-based, so the first attachment is 0. This example adds an attachment and reads its Content-ID (which may be empty when none was assigned).

Background: A Content-ID is a unique identifier for a MIME part. It is essential for inline "related" resources, where HTML references an image by cid:, but ordinary file attachments usually have none. Reading it is useful when inspecting how a message is assembled, or when distinguishing parts that are referenced from the body versus those meant purely as downloadable attachments.

Chilkat Java Downloads

Download Chilkat for Java

Chilkat2 Java

import com.chilkatsoft.chilkat2.Email;

public class ChilkatExample {

    public static void main(String[] args) {
        // Demonstrates the GetAttachmentContentID method, which returns the Content-ID header
        // field for the Nth attachment.  The index is zero-based (the first attachment is 0).

        Email email = new Email();
        email.setSubject("Attachment Content-ID");

        email.addStringAttachment("notes.txt", "Some notes.");

        // Get the Content-ID of the first attachment (may be empty if none was assigned).
        String cid = email.getAttachmentContentID(0);
        System.out.println("Attachment 0 Content-ID: " + cid);
    }
}