通过 GMailSender 发送带有附件的电子邮件？

Question

我一直在阅读博客并尝试了多种实现，但仍然无法将图像附加到我使用 java 通过 GMail 发送的电子邮件中。我下载了所有 jar 并添加了 GMailSender.java、GMailAuthenticator.java 和 JSSEProvider.java，并且我能够正常发送常规电子邮件。我尝试这样做的方式如下所示，中间被注释掉的部分是我希望添加图像的部分。下面是我尝试执行此命令时 logcat 上的输出。当然我错过了一些非常简单的东西。有人可以向我指出吗？提前致谢。

    public synchronized void sendMail(String subject, String body, String sender, String recipients) throws Exception {  
        try {  
            Thread.currentThread().setContextClassLoader(getClass().getClassLoader());  
        MimeMessage message = new MimeMessage(session);  
        DataHandler handler = new DataHandler(new ByteArrayDataSource(body.getBytes(), "text/plain"));  
        message.setSender(new InternetAddress(sender));  
        message.setSubject(subject);  
        message.setDataHandler(handler);  

        /*  
        // Create your new message part  
        BodyPart imgPart = new MimeBodyPart();  

        // Create a related multi-part to combine the parts  
        MimeMultipart multipart = new MimeMultipart("related");  
        multipart.addBodyPart(imgPart);

        String fileName = "http://.../sampleBarcode.png";  

        ClassLoader classLoader = Thread.currentThread().getContextClassLoader();  
        if (classLoader == null) {  
                classLoader = this.getClass().getClassLoader();  
            if (classLoader == null) {  
                System.out.println("IT IS NULL AGAIN!!!!");  
            }  
        }  

        DataSource ds = new URLDataSource(classLoader.getResource(fileName));  
        imgPart.setDataHandler(new DataHandler(ds));  
        imgPart.setHeader("Content-ID", "<logoimg_cid>");  

        multipart.addBodyPart(imgPart);  

        message.setContent(multipart);  
        */  

        if(recipients.indexOf(',') > 0) {  
                message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(recipients));  
        }  
        else message.setRecipient(Message.RecipientType.TO, new InternetAddress(recipients));  

        Transport.send(message);  
        }  
        catch(Exception e){Log.e("EMAIL_ERROR",e.getMessage(), e);}  
    }   

null  
java.lang.NullPointerException  
    at javax.activation.URLDataSource.getContentType(URLDataSource.java:91)  
    at javax.activation.DataHandler.getContentType(DataHandler.java:218)  
    ...  
    ...  
    (plus some more)  

Answer 1

我修改了该函数以接受文件参数并将其附加到电子邮件中，如下所示

public synchronized void sendMail(String subject, String body, String sender, String recipients, File attachment) throws Exception {
    try{
    MimeMessage message = new MimeMessage(session);
    message.setSender(new InternetAddress(sender));
    message.setSubject(subject);

    MimeBodyPart mbp1 = new MimeBodyPart();
    mbp1.setText(body);

    MimeBodyPart mbp2 = new MimeBodyPart();
    FileDataSource fds = new FileDataSource(attachment);
    mbp2.setDataHandler(new DataHandler(fds));
    mbp2.setFileName(fds.getName());

    Multipart mp = new MimeMultipart();
    mp.addBodyPart(mbp1);
    mp.addBodyPart(mbp2);

    message.setContent(mp);

    if (recipients.indexOf(',') > 0)
        message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(recipients));
    else
        message.setRecipient(Message.RecipientType.TO, new InternetAddress(recipients));
    Transport.send(message);
    }catch(Exception e){

    }
}