如何使用 java 邮件 api 发送任何类型的附件？

Question

我可以发送仅附有文本文件的邮件，而且我使用的是文件路径。我想要一个代码使用文件 inputstream

发送任何类型的附件

我可以发送仅附有文本文件的邮件，而且我正在使用文件。

messageBodyPart = new MimeBodyPart();
         String filename = "/home/manisha/file.txt";
         DataSource source = new FileDataSource(filename);
         messageBodyPart.setDataHandler(new DataHandler(source));
         messageBodyPart.setFileName(filename);
         multipart.addBodyPart(messageBodyPart);

我希望代码使用 java api.

发送任何类型的附件

Answer 1

事实证明，ByteArrayDataSource 可用于发送任何类型的流。除了流之外，您还需要指定 mime 类型，因为没有它就无法知道类型。如果 InputStream 表示 jpeg 图像，您将使用 "image/jpeg" 作为传递给 ByteArrayDataSource 的类型。

知道ByteArrayDataSource会把InputStream完全读入字节数组中进行处理。如果 InputStream 非常大，则可能会消耗大量内存。再一次，大多数电子邮件系统限制附件大小。

请注意，此代码尚未准备好生产，需要错误/异常处理。

    messageBodyPart = new MimeBodyPart();
    String filename = "/home/manisha/file.txt";
    //
    // FileInputStream is just for the example. You can use other InputStreams as well.
    //
    InputStream inputStream = new FileInputStream(filename);

    DataSource source;
    try (InputStream inputStream = new FileInputStream(filename)) {
        source = new ByteArrayDataSource(inputStream, "text/plain;charset=UTF-8");
    }
    messageBodyPart.setDataHandler(new DataHandler(source));
    messageBodyPart.setFileName(filename);
    multipart.addBodyPart(messageBodyPart);

    // Send the complete message parts
    message.setContent(multipart);

[编辑] 下面是一些测试 InputStream 是否有数据的代码。您可以使用上面的源调用它以打印出输入流中的字节数。

private static void printDataSourceByteCount(DataSource source) throws IOException {
    try (InputStream is = source.getInputStream()) {

        long totalBytesRead = 0;
        byte [] buffer = new byte[2048];
        int bytesRead = is.read(buffer);
        while(bytesRead > 0) {
            totalBytesRead += bytesRead;
            bytesRead = is.read(buffer);
        }
        System.out.println(String.format("Read %d bytes", totalBytesRead));
    }
}

[编辑] 这是我使用测试 pdf 的功能齐全的示例。只要将 MIME 类型更改为 "text/plain".

，文本文件也能正常工作

public static void main(String[] args) {

    // Recipient's email ID needs to be mentioned.
    String to = "<to email>";

    // Sender's email ID needs to be mentioned
    String from = "<from email>";

    final String username = "<email server username>";// change accordingly
    final String password = "<email server password>";// change accordingly

    // Set to your email server
    String host = "mail.acme.com";

    Properties props = new Properties();
    props.put("mail.smtp.auth", "true");
    props.put("mail.smtp.starttls.enable", "false");
    props.put("mail.smtp.host", host);
    props.put("mail.smtp.port", "25");

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

    try {
        // Create a default MimeMessage object.
        Message message = new MimeMessage(session);

        // Set From: header field of the header.
        message.setFrom(new InternetAddress(from));

        // Set To: header field of the header.
        message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(to));

        // Set Subject: header field
        message.setSubject("Testing Subject");

        // Create the message part
        BodyPart messageBodyPart = new MimeBodyPart();

        // Now set the actual message
        messageBodyPart.setText("Hello. Attached is a very important PDF.");

        // Create a multipar message
        Multipart multipart = new MimeMultipart();

        // Set text message part
        multipart.addBodyPart(messageBodyPart);

        // Part two is attachment
        messageBodyPart = new MimeBodyPart();
        String filename = "/Users/rick/Tmp/test.pdf";

        DataSource source;
        try (InputStream inputStream = new FileInputStream(filename)) {
            source = new ByteArrayDataSource(inputStream, "application/pdf");
        }

        printDataSourceByteCount(source);

        messageBodyPart.setDataHandler(new DataHandler(source));
        messageBodyPart.setFileName("SecretsOfTheUniverse.pdf");
        multipart.addBodyPart(messageBodyPart);

        // Send the complete message parts
        message.setContent(multipart);

        // Send message
        Transport.send(message);

        System.out.println("Sent message successfully....");

    } catch (MessagingException e) {
        // TODO handle the error
        e.printStackTrace();
    } catch (FileNotFoundException e) {
        // TODO handle the error
        e.printStackTrace();
    } catch (IOException e) {
        // TODO handle the error
        e.printStackTrace();
    }
}

如何使用 java 邮件 api 发送任何类型的附件？

How to send any type of attachment using java mail api?

java

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email-attachments