如何使用 MimeMessageHelper 发送带附件的电子邮件？

Question

我无法正确发送带有附件的电子邮件。我正在使用 Gradle 和 Spring 5。一切都设置正确，因为我已经在发送带有文本和 html 的电子邮件。一段时间后，我向客户发送的文本要求超出了电子邮件的限制，因此我需要将纯文本提取到 CSV 文件中，并将其作为附件发送到电子邮件中。 看起来我只收到了文件的一部分，而不是完整的文件？

代码：

for(Entry<String, List<LabDipRequest>> entry : userNotificationMap.entrySet())
    {                           
        javaMailSender.send(mimeMessage -> {
            MimeMessageHelper messageHelper = new MimeMessageHelper(mimeMessage, true);
            messageHelper.setFrom(fromEmail);
            messageHelper.setTo(entry.getKey());
            messageHelper.setSubject("Exception Report");
            String val = ldReport.generateLabDipExceptionReport(entry.getValue());
            messageHelper.setText(val);
            FileSystemResource file = new FileSystemResource(new File("ExceptionReport.csv"));
            messageHelper.addAttachment("ExceptionReport.csv", file);
        });
    }

电子邮件正文无法正确发送。 这是我在电子邮件收件箱中收到的原始消息：

主题：报告
MIME 版本：1.0
内容类型： 多部分/混合；
边界="----=_Part_0_927559004.1603720386263"

如果提供任何额外的说明，我还会输出一个日志：

DEBUG: JavaMail version 1.6.2
DEBUG: successfully loaded resource: /META-INF/javamail.default.address.map
DEBUG: getProvider() returning javax.mail.Provider[TRANSPORT,smtp,com.sun.mail.smtp.SMTPTransport,Oracle]
DEBUG SMTP: useEhlo true, useAuth true
DEBUG SMTP: trying to connect to host "smtp.gmail.com", port 25, isSSL false
220 smtp.gmail.com <hidden> - gsmtp
DEBUG SMTP: connected to host "smtp.gmail.com", port: 25
EHLO mongo.<hidden>.com
250-smtp.gmail.com at your service, [<hidden>]
250-SIZE 35882577
250-8BITMIME
250-STARTTLS
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
DEBUG SMTP: Found extension "SIZE", arg "35882577"
DEBUG SMTP: Found extension "8BITMIME", arg ""
DEBUG SMTP: Found extension "STARTTLS", arg ""
DEBUG SMTP: Found extension "ENHANCEDSTATUSCODES", arg ""
DEBUG SMTP: Found extension "PIPELINING", arg ""
DEBUG SMTP: Found extension "CHUNKING", arg ""
DEBUG SMTP: Found extension "SMTPUTF8", arg ""
STARTTLS
220 2.0.0 Ready to start TLS
EHLO mongo.<hidden>.com
250-smtp.gmail.com at your service, [<hidden>]
250-SIZE 35882577
250-8BITMIME
250-AUTH LOGIN <hidden>
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
DEBUG SMTP: Found extension "SIZE", arg "35882577"
DEBUG SMTP: Found extension "8BITMIME", arg ""
DEBUG SMTP: Found extension "AUTH", arg "<hidden>"
DEBUG SMTP: Found extension "ENHANCEDSTATUSCODES", arg ""
DEBUG SMTP: Found extension "PIPELINING", arg ""
DEBUG SMTP: Found extension "CHUNKING", arg ""
DEBUG SMTP: Found extension "SMTPUTF8", arg ""
DEBUG SMTP: protocolConnect login, host=smtp.gmail.com, user=dummyaccount@gmail.com, password=<non-null>
DEBUG SMTP: Attempt to authenticate using mechanisms: <hidden>
DEBUG SMTP: Using mechanism LOGIN
DEBUG SMTP: AUTH LOGIN command trace suppressed
DEBUG SMTP: AUTH LOGIN succeeded
DEBUG SMTP: use8bit false
MAIL FROM:<dummyaccount@gmail.com>
250 2.1.0 OK <hidden>.33 - gsmtp
RCPT TO:<dummyaccount@gmail.com>
250 2.1.5 OK <hidden>.33 - gsmtp
DEBUG SMTP: Verified Addresses
DEBUG SMTP:   dummyaccount@gmail.com
DATA
354  Go ahead <hidden>.33 - gsmtp
Date: Mon, 26 Oct 2020 10:38:17 -0400 (EDT)
From: dummyaccount@gmail.com
To: dummyaccount@gmail.com
Message-ID: <<hidden>@mongo.<hidden>.com>
Subject: Report
MIME-Version: 1.0
Content-Type: multipart/mixed;
        boundary="----=_Part_0_190448734.1603723096935"

.
250 2.0.0 OK  1603723099 <hidden>.33 - gsmtp
DEBUG SMTP: message successfully delivered to mail server
QUIT
221 2.0.0 closing connection <hidden>.33 - gsmtp

Answer 1

我几乎可以肯定问题出在错误的文件路径上。仅将 FileSystemResource 与 mime 消息一起使用。试试这个代码：

@SneakyThrows
@Async
public void sendEmailWithAttachment(String pathToAttachment) {
    MimeMessage message = emailSender.createMimeMessage();

    MimeMessageHelper helper = new MimeMessageHelper(message, true);

    helper.setSubject(yourSubject);
    helper.setText(yourContent);
    helper.setTo(yourTo);
    helper.setFrom(yourFrom);

    FileSystemResource file = new FileSystemResource(new File(pathToAttachment));
    helper.addAttachment("LabDip", file);

    emailSender.send(message);
}