Dart Requires Chilkat v11.0.0+

Create Binary MIME

See more MIME Examples

Demonstrates how to create and save a multipart/mixed MIME document where the parts (a JPG and a PDF) are NOT base64 encoded, but are instead binary. Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  final mime = CkMime();

  mime.setBodyFromPlainText('This is the plain text body.');
  mime.convertToMultipartMixed();
  mime.appendPartFromFile('qa_data/jpg/penguins.jpg');
  mime.appendPartFromFile('qa_data/pdf/fishing.pdf');

  // At this point, when saved, the MIME bodies will be base64 encoded.
  mime.saveMime('qa_output/sample.txt');

  // We now have the following MIME where everything is base64 encoded:
  // The code that follows shows how to eliminate the base64 to make this binary MIME.

  // 	Content-Type: multipart/mixed; boundary="------------000207060703080505060404"
  // 
  // 	--------------000207060703080505060404
  // 	Content-Type: text/plain
  // 	Content-Transfer-Encoding: 7bit
  // 
  // 	This is the plain text body.
  // 	--------------000207060703080505060404
  // 	Content-Disposition: attachment; filename="penguins.jpg"
  // 	Content-Type: image/jpeg; name="penguins.jpg"
  // 	Content-Transfer-Encoding: base64
  // 
  // 	/9j/4AAQSkZJRgABAgEAYABgAAD/7gAOQWRvYmUAZAAAAAAB/+ESCEV4aWYAAE1NACoAAAAIAAcB
  // 	MgACAAAAFAAAAGIBOwACAAAABwAAAHZHRgADAAAAAQAEAABHSQADAAAAAQA/AACcnQABAAAADgAA
  // 	...
  // 	800a1MlLipJHlyU9en7sqVPkBK+gBj+o+1E91Ld7iJk0pJDO5PmDk4FOGOHy6S3JW120W1uCJ5M0
  // 	PBa54edOFAc8ePX/2Q==
  // 
  // 	--------------000207060703080505060404
  // 	Content-Disposition: attachment; filename="fishing.pdf"
  // 	Content-Type: application/pdf; name="fishing.pdf"
  // 	Content-Transfer-Encoding: base64
  // 
  // 	JVBERi0xLjMKJcfsj6IKNSAwIG9iago8PC9MZW5ndGggNiAwIFIvRmlsdGVyIC9GbGF0ZURlY29k
  // 	ZT4+CnN0cmVhbQp4nM1c288cNxVX09A0myq35tom7bSl8E1hp76P/YpASIiXlEg8tDwVKEJfilIe
  // 	...
  // 	MDRGMT48OTlENkRFQzExQjkzNjA0Mjc1RUFCNzIyMjI4RjA0RjE+XQo+PgpzdGFydHhyZWYKMjk0
  // 	MzY5CiUlRU9GCg==
  // 
  // 	--------------000207060703080505060404--
  // 

  // To make it binary MIME (getting rid of the base64), set the Encoding property to "binary"
  // for the JPG and PDF parts.

  final jpgPart = CkMime();
  mime.partAt(1, jpgPart);

  jpgPart.encoding = 'binary';

  final pdfPart = CkMime();
  mime.partAt(2, pdfPart);

  pdfPart.encoding = 'binary';

  // Now save it.  If you try to view this MIME in a text editor,
  // the JPG and PDF parts will be garbled and unintelligible. That's because
  // the bytes do not represent characters.
  mime.saveMime('qa_output/sampleBinary.mim');

  // The MIME now contains this:

  // 	Content-Type: multipart/mixed; boundary="------------000207060703080505060404"
  // 
  // 	--------------000207060703080505060404
  // 	Content-Type: text/plain
  // 	Content-Transfer-Encoding: 7bit
  // 
  // 	This is the plain text body.
  // 	--------------000207060703080505060404
  // 	Content-Disposition: attachment; filename="penguins.jpg"
  // 	Content-Type: image/jpeg; name="penguins.jpg"
  // 	Content-Transfer-Encoding: binary
  // 
  // 	<Binary Data Here>
  // 
  // 	--------------000207060703080505060404
  // 	Content-Disposition: attachment; filename="fishing.pdf"
  // 	Content-Type: application/pdf; name="fishing.pdf"
  // 	Content-Transfer-Encoding: binary
  // 
  // 	<Binary Data Here>
  // 
  // 	--------------000207060703080505060404--
  // 

  // Can we load this binary MIME into an Email object?
  final binData = CkBinData();
  // Write the binary MIME into binData;
  mime.getMimeBd(binData);

  final email = CkEmail();
  // Load the email from the binData.
  email.setFromMimeBd(binData);

  // Note: Many email clients may not be able to correctly process emails
  // using the binary encoding.  Thunderbird has trouble.  Windows Live Mail
  // worked OK.
  email.subject = 'Binary MIME Email';
  email.from = 'admin@chilkatsoft.com';
  email.addTo('Chilkat', 'support@chilkatsoft.com');
  email.saveEml('qa_output/binaryEmail.eml');

  // Chilkat does not recommend trying to use binary MIME for email.
  // Binary MIME is typically used in HTTP for uploads and downloads.
  // 

  // Also, binary MIME is not representable in a string.  
  // If we try to get the MIME as a string, then it must be encoded
  // using base64.

  // Chilkat automatically changes binary encodings to base64
  // when there's an attempt to get the MIME as a string.
  final sb = CkStringBuilder();
  email.getMimeSb(sb);
  sb.writeFile('qa_output/email_fromSb.eml', 'utf-8', false);

  // Likewise, if we try to get the MIME as a string from the Mime object, 
  // it cannot contain non-character data in a binary encoding.  The binary
  // bytes MUST be in base64.  The act of trying to retrieve the MIME in string
  // format will force Chilkat to convert binary encodings (for non-text parts)
  // to base64.
  mime.getMimeSb(sb);
  sb.writeFile('qa_output/mime_fromSb.eml', 'utf-8', false);

  // However, the above use of base64 is just for the purpose of making the MIME
  // string friendly.  If we save the MIME to a file, it's still binary:
  mime.saveMime('qa_output/mime_binary.mime');
}