Java

Get a Header Attribute of a Related Item

Demonstrates the Chilkat Email.GetRelatedAttr method, which returns a header-field attribute value from a header field of the Nth related item. The first argument is the zero-based related-item index, the second names a header field, and the third names an attribute within it. This example loads an image from a file into a BinData object, adds it as a related item with AddRelatedBd (capturing the generated Content-ID and referencing it from the HTML), then reads the name attribute of the related item's Content-Type header.

Background: Related items (inline images, style sheets) are MIME parts whose headers may carry named parameters — for instance Content-Type: image/png; name="logo.png". Because an image is binary, it is loaded into a BinData object (here from a file) and added with AddRelatedBd, rather than being treated as text. GetRelatedAttr then extracts one named attribute from a chosen header of a specific related part, the related-item analogue of GetAttachmentAttr, so you don't have to parse the raw header yourself.

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import com.chilkatsoft.chilkat2.BinData;
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 GetRelatedAttr method, which returns a header-field attribute value
        // from a header field of the Nth related item.  The first argument is the zero-based related-item
        // index, the second is the header field name, and the third is the attribute name.

        Email email = new Email();
        email.setSubject("GetRelatedAttr example");

        // Load the image data from a file into a BinData object.
        BinData bdImage = new BinData();
        String cid;
        try {
            bdImage.loadFile("qa_data/images/logo.png");

            // Add the image as a related item from the BinData; capture its generated Content-ID.
            cid = email.addRelatedBd("logo.png", bdImage);
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        // Reference the related item in the HTML body by its Content-ID.
        StringBuilder sbHtml = new StringBuilder();
        sbHtml.append("<html><body><img src=\"cid:PLACEHOLDER_CID\"/></body></html>");
        int numReplaced = sbHtml.replace("PLACEHOLDER_CID", cid);
        email.setHtmlBody(sbHtml.getAsString());

        // Get the "name" attribute of the related item's Content-Type header (index 0).
        String val = email.getRelatedAttr(0, "Content-Type", "name");
        System.out.println("Related item Content-Type name attribute: " + val);

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