我正在嘗試向我的郵件發件人添加一個附件按鈕。我正在使用 JavaMail Mail、activation 和 additionalnal 庫。我的發件人被分成 3 個文件：允許用戶設置郵件內容的MainActivity編輯文本SendMail允許我設置發件人，以及從編輯文本到郵件的內容并發送存儲發送者地址和密碼以及接收者地址等信息的配置這是我的實際郵件發件人的代碼，它可以正確發送郵件但沒有附件。發送郵件.javapackage com.myapp.attch_mail;import android.annotation.SuppressLint;import android.app.ProgressDialog;import android.content.Context;import android.os.AsyncTask;import android.widget.Toast;import java.util.Properties;import javax.mail.Message;import javax.mail.MessagingException;import javax.mail.PasswordAuthentication;import javax.mail.Session;import javax.mail.Transport;import javax.mail.internet.InternetAddress;import javax.mail.internet.MimeMessage;public class SendMail extends AsyncTask<Void,Void,Void> {private Context context;private String subject;private String message;private ProgressDialog progressDialog;SendMail(Context context, String subject, String message){    this.context = context;    this.subject = subject;    this.message = message;}@Overrideprotected void onPreExecute() {    super.onPreExecute();    progressDialog = ProgressDialog.show(context,"Envoi en cours","Veuillez patienter...",false,false);}@Overrideprotected void onPostExecute(Void aVoid) {    super.onPostExecute(aVoid);    progressDialog.dismiss();    Toast.makeText(context,"Message sent",Toast.LENGTH_LONG).show();}@Overrideprotected Void doInBackground(Void... params) {    Properties props = new Properties();    props.put("mail.smtp.host", "smtp.gmail.com");    props.put("mail.smtp.socketFactory.port", "465");    props.put("mail.smtp.socketFactory.class", "javax.net.ssl.SSLSocketFactory");    props.put("mail.smtp.auth", "true");    props.put("mail.smtp.port", "465");    Session session = Session.getDefaultInstance(props,            new javax.mail.Authenticator() {                protected PasswordAuthentication getPasswordAuthentication() {                    return new PasswordAuthentication(Config.EMAIL_SENDER, Config.PASSWORD);                }            });