java - 如何使用java从另一个类调用文件对象并通过电子邮件将其作为附件发送？

Question

我有一个 A 类，其中有文件对象和另一个 B 类，用于发送带有附件的电子邮件。我尝试做的是，从 classB 中的 classA 获取文件对象，并通过电子邮件作为附件发送。

当我执行代码时，它会以附件形式发送文件，但在电子邮件中，该文件没有名称。

A类:

import java.io.File;
import javax.mail.MessagingException;

public class A{
    public void A(){
       System.out.println("Sending the file...");
       File file = new File("c:\\temp\\FileA.txt");
    }   
}

B类:

public class B {
    public static void B(File file) throws MessagingException {
        String host = "smtp.gmail.com";
        String Password = "***";
        String from = "***@gmail.com";
        String toAddress = "***@gmail.com";

        //Here i don t want to use this file
        //String filename = "C:/file.txt";

        // Get system properties
        Properties props = System.getProperties();
        props.put("mail.smtp.host", host);
        props.put("mail.smtps.auth", "true");
        props.put("mail.smtp.starttls.enable", "true");
        Session session = Session.getInstance(props, null);

        MimeMessage message = new MimeMessage(session);
        message.setFrom(new InternetAddress(from));
        message.setRecipients(Message.RecipientType.TO, toAddress);
        message.setSubject("Attachment TEST ");

        BodyPart messageBodyPart = new MimeBodyPart();
        messageBodyPart.setText("coucou the file is here");

        Multipart multipart = new MimeMultipart();
        multipart.addBodyPart(messageBodyPart);

        messageBodyPart = new MimeBodyPart();

        DataSource source = new FileDataSource(file);

        messageBodyPart.setDataHandler(new DataHandler(source));
        //messageBodyPart.setFileName(file);

        multipart.addBodyPart(messageBodyPart);

        message.setContent(multipart);

        try {
            Transport tr = session.getTransport("smtps");
            tr.connect(host, from, Password);
            tr.sendMessage(message, message.getAllRecipients());
            System.out.println("Mail Sent Successfully");
            tr.close();
        } catch (SendFailedException sfe) {
            System.out.println(sfe);
        }
    }
    public static void main(String args[]) throws MessagingException{
        B file = new B();
    }
}

我应该怎样做才能获取电子邮件中的确切文件名？谢谢

Answer 1

当您定义了一个具有类名称(在 B 类内部)的方法时，我不明白您的代码是如何运行的。构造函数没有返回类型

您的代码存在问题:-

1)file变量是A类构造函数中的局部变量，应该声明为实例字段

import java.io.File;
import javax.mail.MessagingException;

public class A{

    File file;
    public void A() throws IOException{

     System.out.println("Sending the file...");
     file = new File("c:\\temp\\FileA.txt");
    }   
}

2)您定义了一个具有类名称的方法(在B类中)。构造函数没有返回类型

3)设置附件名称已被注释掉。取消注释并传递一个 String 而不是 File Object 。

messageBodyPart.setFileName(file.getName());

B 类的最终代码(不过我还没有在 IDE 中编译它:)

public class B {

    public B(A aa) throws MessagingException {

        File file = aa.file;

        String host = "smtp.gmail.com";
        String Password = "***";
        String from = "***@gmail.com";
        String toAddress = "***@gmail.com";

        //Here i don t want to use this file
        //String filename = "C:/file.txt";

        // Get system properties
        Properties props = System.getProperties();
        props.put("mail.smtp.host", host);
        props.put("mail.smtps.auth", "true");
        props.put("mail.smtp.starttls.enable", "true");
        Session session = Session.getInstance(props, null);

        MimeMessage message = new MimeMessage(session);

        message.setFrom(new InternetAddress(from));

        message.setRecipients(Message.RecipientType.TO, toAddress);

        message.setSubject("Attachment TEST ");

        BodyPart messageBodyPart = new MimeBodyPart();

        messageBodyPart.setText("coucou the file is here");

        Multipart multipart = new MimeMultipart();

        multipart.addBodyPart(messageBodyPart);

        messageBodyPart = new MimeBodyPart();

        DataSource source = new FileDataSource(file);

        messageBodyPart.setDataHandler(new DataHandler(source));

        messageBodyPart.setFileName(file.getName());

        multipart.addBodyPart(messageBodyPart);

        message.setContent(multipart);

        try {
            Transport tr = session.getTransport("smtps");
            tr.connect(host, from, Password);
            tr.sendMessage(message, message.getAllRecipients());
            System.out.println("Mail Sent Successfully");
            tr.close();

        } catch (SendFailedException sfe) {

            System.out.println(sfe);
        }
    }
    public static void main(String args[]) throws MessagingException{

        A aaa = new A();
        B file = new B(aaa);
    }
}