Transport.send(消息)无法在下面的代码中工作.. netbeans卡在运行部分.它不会继续下去......它永远挂在那里

Question

我曾尝试编写使用Java发送电子邮件的代码.但是这段代码不起作用.当代码执行时,它会卡在transport.send(消息)上.它永远停留在那里.此外,我不确定其余代码是否正确.

  //first from, to, subject, & text values are set
    public class SendMail {
    private String from;
    private String to;
    private String subject;
    private String text;


    public SendMail(String from, String to, String subject, String text){
        this.from = from;
        this.to = to;
        this.subject = subject;
        this.text = text;
    }

    //send method is called in the end 
    public void send(){

        Properties props = new Properties();
        props.put("mail.smtp.host", "smtp.gmail.com");
        props.put("mail.smtp.port", "465");

        Session mailSession = Session.getDefaultInstance(props);
        Message simpleMessage = new MimeMessage(mailSession);

        InternetAddress fromAddress = null;
        InternetAddress toAddress = null;
        try {
            fromAddress = new InternetAddress(from);
            toAddress = new InternetAddress(to);
        } catch (AddressException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        try {
            simpleMessage.setFrom(fromAddress);
            simpleMessage.setRecipient(RecipientType.TO, toAddress);
            simpleMessage.setSubject(subject);
                    simpleMessage.setText(text);
            Transport.send(simpleMessage);  // this is where code hangs     
        } catch (MessagingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }       
    }
}

Answer 1

我遇到了完全相同的问题,其他人报告了间歇性故障.原因是带有SMTP的Transport.send有两个无限超时,这可能导致您的进程挂起!

来自SUN文档:

mail.smtp.connectiontimeout int套接字连接超时值,以毫秒为单位.默认为无限超时.

mail.smtp.timeout int套接字I/O超时值,以毫秒为单位.默认为无限超时.

要不永远"挂起",您可以明确地设置它们:

来自SUN:属性始终设置为字符串; Type列描述了如何解释字符串.例如,使用

    props.put("mail.smtp.port", "888");

请注意,如果您使用"smtps"协议访问SMTP over SSL,则所有属性都将命名为"mail.smtps.*".

因此,如果设置两个超时,则应该得到一个"MessagingException",您可以使用try/catch处理它,而不是让进程挂起.

假设您正在使用smtp,请添加以下内容,其中t1和t2是您的超时时间:

    props.put("mail.smtp.connectiontimeout", "t1");
    props.put("mail.smtp.timeout", "t2");

当然,这不会解决超时的根本原因,但它可以让您优雅地处理问题.

感谢Siegfried Goeschl关于Apache Commons的帖子

PS:我遇到的问题的根本原因似乎与我在旅行时使用的网络连接有关.显然,连接导致SMTP超时,我没有与任何其他连接.

Answer 2

请尝试这个，

    public class SMTPDemo {

  public static void main(String args[]) throws IOException,
      UnknownHostException {
    String msgFile = "file.txt";
    String from = "java2s@java2s.com";
    String to = "yourEmail@yourServer.com";
    String mailHost = "yourHost";
    SMTP mail = new SMTP(mailHost);
    if (mail != null) {
      if (mail.send(new FileReader(msgFile), from, to)) {
        System.out.println("Mail sent.");
      } else {
        System.out.println("Connect to SMTP server failed!");
      }
    }
    System.out.println("Done.");
  }

  static class SMTP {
    private final static int SMTP_PORT = 25;

    InetAddress mailHost;

    InetAddress localhost;

    BufferedReader in;

    PrintWriter out;

    public SMTP(String host) throws UnknownHostException {
      mailHost = InetAddress.getByName(host);
      localhost = InetAddress.getLocalHost();
      System.out.println("mailhost = " + mailHost);
      System.out.println("localhost= " + localhost);
      System.out.println("SMTP constructor done\n");
    }

    public boolean send(FileReader msgFileReader, String from, String to)
        throws IOException {
      Socket smtpPipe;
      InputStream inn;
      OutputStream outt;
      BufferedReader msg;
      msg = new BufferedReader(msgFileReader);
      smtpPipe = new Socket(mailHost, SMTP_PORT);
      if (smtpPipe == null) {
        return false;
      }
      inn = smtpPipe.getInputStream();
      outt = smtpPipe.getOutputStream();
      in = new BufferedReader(new InputStreamReader(inn));
      out = new PrintWriter(new OutputStreamWriter(outt), true);
      if (inn == null || outt == null) {
        System.out.println("Failed to open streams to socket.");
        return false;
      }
      String initialID = in.readLine();
      System.out.println(initialID);
      System.out.println("HELO " + localhost.getHostName());
      out.println("HELO " + localhost.getHostName());
      String welcome = in.readLine();
      System.out.println(welcome);
      System.out.println("MAIL From:<" + from + ">");
      out.println("MAIL From:<" + from + ">");
      String senderOK = in.readLine();
      System.out.println(senderOK);
      System.out.println("RCPT TO:<" + to + ">");
      out.println("RCPT TO:<" + to + ">");
      String recipientOK = in.readLine();
      System.out.println(recipientOK);
      System.out.println("DATA");
      out.println("DATA");
      String line;
      while ((line = msg.readLine()) != null) {
        out.println(line);
      }
      System.out.println(".");
      out.println(".");
      String acceptedOK = in.readLine();
      System.out.println(acceptedOK);
      System.out.println("QUIT");
      out.println("QUIT");
      return true;
    }
  }
}