Java 必须首先发出STARTTLS命令。-gsmtp；使用gmail帐户发送带有附件的电子邮件

我是编程新手，很抱歉解释得不清楚。我尝试了谷歌上几乎所有可用的答案。但无法找出出现错误的原因。此代码的目的是附加文件并将其发送到电子邮件地址。我没有任何电子邮件服务器

import java.util.Properties;    
import javax.activation.DataHandler;
import javax.activation.DataSource;
import javax.activation.FileDataSource;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;

public class SendEmailMain {

public static void main(String[] args) {

    final String username = "myusername@gmail.com";
    final String password = "mypassword";
    String emailID = "receiversUserName@yahoo.com";

    Properties props = new Properties();
    props.put("mail.smtp.starttls.enable", true);
    props.put("mail.smtp.auth", true);
    props.put("mail.smtp.host", "smtp.gmail.com");
    props.put("mail.smtp.port", "587");

    Session session = Session.getInstance(props,
            new javax.mail.Authenticator() {
                protected PasswordAuthentication getPasswordAuthentication() {
                    return new PasswordAuthentication(username, password);
                }
            });

    try {

        Message message = new MimeMessage(session);
        message.setFrom(new InternetAddress(username));
        message.setRecipients(Message.RecipientType.TO,
                InternetAddress.parse(emailID));
        message.setSubject("Testing Subject");
        message.setText("PFA");

        MimeBodyPart messageBodyPart = new MimeBodyPart();

        Multipart multipart = new MimeMultipart();

        messageBodyPart = new MimeBodyPart();
        String file = "snap1.jpg";
        String fileName = "attachmentName";
        DataSource source = new FileDataSource(file);
        messageBodyPart.setDataHandler(new DataHandler(source));
        messageBodyPart.setFileName(fileName);
        multipart.addBodyPart(messageBodyPart);

        message.setContent(multipart);

        System.out.println("Sending");

        Transport.send(message);

        System.out.println("Done");

    } catch (MessagingException e) {
        e.printStackTrace();
    }
}
}

eclipse控制台中的错误消息

Sending
com.sun.mail.smtp.SMTPSendFailedException: 530 5.7.0 Must issue a STARTTLS command first. of6sm3574020lbb.11 - gsmtp
at com.sun.mail.smtp.SMTPTransport.issueSendCommand(SMTPTransport.java:1388)
at com.sun.mail.smtp.SMTPTransport.mailFrom(SMTPTransport.java:959)
at com.sun.mail.smtp.SMTPTransport.sendMessage(SMTPTransport.java:583)
at javax.mail.Transport.send0(Transport.java:169)
at javax.mail.Transport.send(Transport.java:98)
at me.screenful.screenshot.ScreenShotTaker.SendEmailMain.main(SendEmailMain.java:70)

---

我已经找到了它不起作用的原因。因为我把谷歌的代码复制到了我的项目中。在代码中

props.put("mail.smtp.starttls.enable", true);
props.put("mail.smtp.auth", true);

值true不是用倒逗号表示的。应该是这样的

props.put("mail.smtp.starttls.enable", "true");
props.put("mail.smtp.auth", "true");

如果出现错误，“530 5.7.0必须首先发出STARTTLS命令。”在运行时。
在IDE中：

右键单击项目。单击运行方式，然后单击运行配置

您可以在VM参数框的（X）=参数选项卡中设置参数“-Dmail.smtp.starttls.enable=true”

单击运行按钮

或

在命令提示下：

您正在为java程序提供参数

java-Dmail.smtp.starttls.enable=true.java