Create email with body and attachments for binary payload with Java mapping

package sample;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.xml.bind.DatatypeConverter;
import com.sap.aii.mapping.api.AbstractTransformation;
import com.sap.aii.mapping.api.StreamTransformationException;
import com.sap.aii.mapping.api.TransformationInput;
import com.sap.aii.mapping.api.TransformationOutput;

public class MyBinaryMessageAsAttachment extends AbstractTransformation {

  String attachmentName = "file.pdf";
  String boundary = "-" + "-" + "AaZz"; //
  String contentType = "multipart/mixed; boundary=\"" + boundary + "\"";
  String mailContent = "This is a sample file";
  String CRLF = "\r\n";

  public void transform (TransformationInput arg0, TransformationOutput arg1)  
                        throws StreamTransformationException {

    InputStream in = arg0.getInputPayload().getInputStream();
    OutputStream out = arg1.getOutputPayload().getOutputStream();
    try {
        // create the declaration of the MIME parts
        //First part
        String output = "-" + "-" + boundary + CRLF
               + "Content-Type: text/plain; charset=UTF-8" + CRLF
               + "Content-Disposition: inline" + CRLF + CRLF
               + mailContent // this should be some more useful text
               + CRLF + CRLF
    
        //Second part
               + "-" + "-" + boundary + CRLF
               + "Content-Transfer-Encoding: base64" + CRLF
               + "Content-Type: application/pdf; name=" 
               + attachmentName + CRLF
               + "Content-Disposition: attachment; filename=" 
               + attachmentName + CRLF + CRLF;
        out.write(output.getBytes());

        // convert InputStream to Byte array
        byte[] input = new byte[in.available()];
        in.read(input);
    
        // convert payload to base64
        output = DatatypeConverter.printBase64Binary(input);

        // split lines after 76 rows
        output = addLinefeeds(output);
        out.write(output.getBytes());

        // last boundary
        output = CRLF + CRLF + "-" + "-" + boundary + "-" + "-" + CRLF;
        out.write(output.getBytes());

        // set content type to message header
        arg1.getOutputHeader().setContentType(contentType);
    } catch (IOException e) {
        throw new StreamTransformationException(e.getMessage());
    }

  }




  public String addLinefeeds(String str) {

    StringBuffer result = new StringBuffer(str);
    int n = 76; // split by 76 characters (maximum of numbers in lines)
    int l = str.length();
    int i = n;

    while (l > n) {
        result.insert(i, CRLF);
        i = i + n + 2;
        l = l - n;
    }
    return result.toString();
  }

}

—-AaZz

Content-Type: text/plain; charset=UTF-8

Content-Disposition: inline

This is a sample file

—-AaZz

Content-Transfer-Encoding: base64

Content-Type: application/pdf; name=file.pdf

Content-Disposition: attachment; filename=file.pdf

PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iVVRGLTgiPz4KPGNmZGk6Q29tcHJvYmFudGUg

cnRlPSIxNjA4Ni4xMyI+PC9jZmRpOlRyYXNsYWRvPjwvY2ZkaTpUcmFzbGFkb3M+PC9jZmRpOklt

cHVlc3Rvcz48Y2ZkaTpDb21wbGVtZW50bz48L2NmZGk6Q29tcGxlbWVudG8+PC9jZmRpOkNvbXBy

b2JhbnRlPg==

—-AaZz–