小賴的實戰記錄

下載附件參考

https://www.codejava.net/java-ee/javamail/download-attachments-in-e-mail-messages-using-javamail

先判斷是否有附件，看ContentType是否為multipart

String contentType = message.getContentType();

if(contentType.contains("multipart")){
    //JUST DO IT
}

然後取得內容並轉成Mutipart，並輸入為檔案

Multipart multiPart = (Multipart)message.getContent();
for (int j = 0; j < multiPart.getCount(); j++) {
	 MimeBodyPart part = (MimeBodyPart) multiPart.getBodyPart(j);
	 if (Part.ATTACHMENT.equalsIgnoreCase(part.getDisposition())) {
	      // this part is attachment
	      // code to save attachment...
	      String destFilePath = downloadDir + "/"+ part.getFileName();
	      FileOutputStream output = new FileOutputStream(destFilePath);
	      InputStream input = part.getInputStream();
	        				 
	      byte[] buffer = new byte[4096];
	        				  
	      int byteRead;
	        				  
	      while ((byteRead = input.read(buffer)) != -1) {
	        	output.write(buffer, 0, byteRead);
	      }
	      output.close();
	  }
}

然後就，完成了。