Java

Add a Related File to an HTML Email

Demonstrates the Chilkat Email.AddRelatedFile method, which adds the contents of a local file as a related MIME resource and returns the generated Content-ID. The returned value is the bare Content-ID — no angle brackets and no cid: prefix — so if it returns CID-123@example, the HTML reference is cid:CID-123@example. Because the Content-ID is generated by the call, this example adds the image first, then builds the HTML body in a StringBuilder — using a placeholder in the <img> tag that is replaced with the returned Content-ID — and passes the result to SetHtmlBody.

Background: To embed an image so it displays inside an HTML email (rather than being downloaded from a web server), you add it as a "related" part and reference it from the HTML with a cid: URL that matches the part's Content-ID. Since Chilkat assigns that ID when you add the file, the natural order is: add the related file, capture the returned ID, then build the <img src="cid:..."> reference from it. A StringBuilder makes assembling and updating the HTML convenient.

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import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Email;
import com.chilkatsoft.chilkat2.StringBuilder;

public class ChilkatExample {

    public static void main(String[] args) {
        // Demonstrates the AddRelatedFile method, which adds a local file as a related MIME
        // resource (such as an image displayed by an HTML body) and returns the generated
        // Content-ID.  The HTML references the item using cid:<Content-ID>.

        Email email = new Email();
        email.setSubject("Email with a related image");

        // Add the image file as a related item first.  The return value is the bare Content-ID
        // (no angle brackets and no "cid:" prefix).
        String cid;
        try {
            cid = email.addRelatedFile("qa_data/images/logo.png");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Build the HTML body in a StringBuilder, using a placeholder where the image's
        // Content-ID will go.
        StringBuilder sbHtml = new StringBuilder();
        sbHtml.append("<html><body><img src=\"cid:PLACEHOLDER_CID\"/></body></html>");

        // Replace the placeholder with the actual Content-ID returned by AddRelatedFile.
        int numReplaced = sbHtml.replace("PLACEHOLDER_CID", cid);

        // Set the HTML body from the StringBuilder result.
        email.setHtmlBody(sbHtml.getAsString());

        System.out.println("Related Content-ID = " + cid);
        System.out.println("NumRelatedItems = " + email.getNumRelatedItems());

        // Note: The path "qa_data/images/logo.png" is a relative local filesystem path,
        // relative to the current working directory of the running application.
    }
}