不能使用gmail-smtp和javamail发送电子邮件？

Question

I'm using Javamail to sned the email from my gmail to others but the system couldn't send it. It keeps on saying it couldn't load main class.

The code I got was a demo code so I think it's not the problem. Anyhow, I'm posting it here.

package Email;

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 SendMailTLS {

    public static void main(String[] args) {

        final String username = "abc@gmail.com";
        final String password = "abc";

        Properties props = new Properties();
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.starttls.enable", "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("abc@gmail.com"));
            message.setRecipients(Message.RecipientType.TO,
                InternetAddress.parse("def@gmail.com"));
            message.setSubject("Testing Subject");
            message.setText("Dear Mail Crawler,"
                + "\n\n No spam to my email, please!");

            Transport.send(message);

            System.out.println("Done");

        } catch (MessagingException e) {
            throw new RuntimeException(e);
        }
    }
}

Now, I've set my CLASSPATH with all the jar in D:\\... and also the place where I store my .java file. There's no space in the link. When I compiled, the program did it just fine. The problem started when I tried to run the code.

`

PS D:\Documents\java> javac SendMailTLS.java
PS D:\Documents\java> java SendMailTLS
Error: Could not find or load main class SendMailTLS
PS D:\Documents\java>
PS D:\Documents\java> java Email.SendMailTLS
Error: Could not find or load main class Email.SendMailTLS
PS D:\Documents\java>
PS D:\Documents\java> java .Email.SendMailTLS
Error: Could not find or load main class .Email.SendMailTLS
PS D:\Documents\java>
PS D:\Documents\java> java -cp D:\Documents\java\ Email.SendMailTLS
Error: Could not find or load main class Email.SendMailTLS
PS D:\Documents\java>
PS D:\Documents\java> java -cp D:\Documents\java\ SendMailTLS
Error: Could not find or load main class SendMailTLS
PS D:\Documents\java>
`

Any idea why it's like this?

Thanks a lot in advance.

Zestos.

Answer 1

You declare your class to be in the package "Email". The class loader will search for this class in a subdirectory "Email", not in the current directory. Create a directory "Email" in a directory of your classpath, or under the current directory, and move your class there. Then call the class as Email.SendMailTLS

Alternatively just remove the package statement from your class.

BTW, naming convention is to keep the package name in lowercase.

Answer 2

像这样将属性mail.smtp.starttls.enable的值更改为false：

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