Android : how to set mime type as image/jpeg in multipart file upload in android

Am building an app which requires file uploading to the server .I used multer (node modules) at the server end , The file is uploaded successfully and file is in the uploads folder ,The problem is i need to parse the file based on the mimetype , But when i Upload the mimetype for each file is application/octet-stream

File sourceFile = new File(filePath);
entity.addPart("file", new FileBody(sourceFile));
totalSize = entity.getContentLength();
httppost.setEntity(entity);

I wanna manually set the mimetype of the file while uploading it into the server.