Java

Set a MIME Header Field

Demonstrates the Chilkat Mime.SetHeaderField method, which sets a single header field. The first argument is the field name and the second is the value. All existing occurrences are removed and one replacement is inserted, or a new field is added if none exists.

Background: For headers that should appear exactly once — Subject, From, Content-Type — this is the method to use, because it guarantees a single occurrence no matter how many times you call it. That idempotence is the key difference from AddHeaderField, which would leave duplicates behind. Setting an empty value removes the field.

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Chilkat2 Java

import com.chilkatsoft.chilkat2.ChilkatException;
import com.chilkatsoft.chilkat2.Mime;

public class ChilkatExample {

    public static void main(String[] args) {
        // Demonstrates the Mime.SetHeaderField method, which sets a single header field.  The 1st argument
        // is the field name and the 2nd is the value.  All existing occurrences are removed and one
        // replacement is inserted (or a new field is added if none exists).

        Mime mime = new Mime();

        try {
            mime.setBodyFromPlainText("Hello.");

            // Unlike AddHeaderField, SetHeaderField ensures exactly one field with this name.
            mime.setHeaderField("Subject", "Weekly Report");

            // Setting it again replaces the previous value rather than adding a duplicate.
            mime.setHeaderField("Subject", "Weekly Report (revised)");
        } catch (ChilkatException e) {
            System.out.println(e.getLastErrorText());
            return;
        }

        String subject = mime.getHeaderField("Subject");
        if (subject == null) {
            System.out.println(mime.getLastErrorText());
            return;
        }

        System.out.println("Subject: " + subject);
    }
}