(Java) The MIME Content-Type Header Field

Explains the ContentType property and the Content-Type header field including the various attributes that may be included.

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import com.chilkatsoft.*;

public class ChilkatExample {

  static {
    try {
        System.loadLibrary("chilkat");
    } catch (UnsatisfiedLinkError e) {
      System.err.println("Native code library failed to load.\n" + e);
      System.exit(1);
    }
  }

  public static void main(String argv[])
  {
    // Every part in a MIME messsage should include a Content-Type header field.
    // The Content-Type indicates the type of content contained in the MIME part.
    // For example: text/plain, image/jpeg, application/pdf, application/json, multipart/mixed, etc.

    // Multipart content types are those where the MIME part's body is composed of N inner MIME messages,
    // separated by a boundary string.
    // This is how MIME gets a nested, tree-like structure.  The most common multipart MIME types
    // are (for email related MIME) multipart/mixed, multipart/alternative, and multipart/related,
    // and for HTTP related MIME, it is multipart/form-data.

    boolean success;
    CkMime mime = new CkMime();

    // The Content-Type header field can be set or modified in two ways.
    // 1) By setting the ContentType, Micalg, Name, Charset, Boundary, or Protocol properties.
    //    Setting the ContentType property sets the primary value (such as "text/plain") of the header field.
    //    Each of the other properties listed above will replace or add a particular attribute value.

    // 2) By setting the entire contents of the ContentType header with the SetHeaderField method.
    //    This updates each of the Content-Type related properties.

    // For example:
    mime.put_ContentType("text/plain");
    mime.put_Charset("utf-8");

    // The Content-Type header field contains this:
    //     Content-Type: text/plain; charset=utf-8
    System.out.println(mime.getEntireHead());
    System.out.println("-");

    mime.SetHeaderField("Content-Type","image/jpeg; name=\"kitty.jpg\"");
    // The Content-Type header field now contains this:
    //     Content-Type: image/jpeg; name="kitty.jpg"
    System.out.println(mime.getEntireHead());
    System.out.println("-");

    // Notice how the properties have been updated:
    System.out.println("ContentType property: " + mime.contentType());
    System.out.println("Charset property: " + mime.charset());
    System.out.println("Name property: " + mime.name());
    System.out.println("-");

    // To change a particular attribute value, set the property.
    mime.put_Name("doggy.jpg");
    System.out.println(mime.getEntireHead());
    System.out.println("-");

    // To remove an attribute value from the Content-Type header,
    // set the property to an empty string.
    mime.put_Name("");
    System.out.println(mime.getEntireHead());
    System.out.println("-");
  }
}