java mail Base64 encoded string to image attachment

Question

I have a base64 encoded string which is posted using JSON into a Spring form.

data:image/png;base64,iVBORw0KGg......etc

I want to add this

Answer 1

With the answer of @jmehrens I was able to attach a file, but they couldn't be opened. Turned out you need to set the datatype seperately and remove it from the given fileContent String:

{
   String dataType = StringUtils.substringBetween(file, "data:", ";base64,"); // extract data type (dataType = "image/png") 
base64EncodedFileContent = fileContent.replaceFirst("data:.*;base64,", ""); // remove prefix from fileContent String (base64EncodedFileContent = "iVBORw0KGg......etc"

    MimeBodyPart filePart = new PreencodedMimeBodyPart("base64");
    filePart.setContent(base64EncodedFileContent, dataType);
    filePart.setFileName(fileName);

    return filePart;
 }