java - Spring MVC java邮件IMAP，如何在thymeleaf中显示通过表单收到的电子邮件列表？

Question

我正在制作一个电子邮件客户端应用程序，为此我使用 Spring MVC 和“javax.mail”邮件 API，以及用于 View 的 thymeleaf。我已经将服务配置为通过 IMAP 读取消息，到目前为止一切顺利，我遇到的问题是，当我尝试通过 View 中的表单显示电子邮件列表时，我只能看到列表中的一项，尽管在debug 可以看到指定文件夹(收件箱)中的所有邮件都列出来了。那么如何通过thymeleaf中的表单显示“收件箱”文件夹的电子邮件列表呢？

public class ReadDto {

    private String from;
    private String subject;
    private Date sentDate;

    public ReadDto() {
    }

    public ReadDto(String from, String subject, Date sentDate) {
        this.from = from;
        this.subject = subject;
        this.sentDate = sentDate;
    }

    public String getFrom() {
        return from;
    }

    public void setFrom(String from) {
        this.from = from;
    }

    public String getSubject() {
        return subject;
    }

    public void setSubject(String subject) {
        this.subject = subject;
    }

    public Date getSentDate() {
        return sentDate;
    }

    public void setSentDate(Date sentDate) {
        this.sentDate = sentDate;
    }
}

我的服务:

public interface EmailReadService {
    ReadDto downloadEmails();
}

实现:

    @Override
    public ReadDto downloadEmails(){

        ReadDto readDto = new ReadDto();

        if (getLoginSession()==null){
            logger.error("Session error!");
        }

        try {
            store = getLoginSession().getStore(emailAccountComponent.getProtocol());
            store.connect(connectService.javaMailSenderImpl.getHost(),
                        connectService.javaMailSenderImpl.getUsername(),
                        connectService.javaMailSenderImpl.getPassword());

            folder = store.getFolder(emailAccountComponent.getFolder());
            folder.open(Folder.READ_ONLY);

            Message[] messages = folder.search(new FlagTerm(new Flags(Flags.Flag.SEEN), false));
            for (Message message: messages){
                readDto.setFrom(Arrays.toString(message.getFrom()));
                readDto.setSubject(message.getSubject());
                readDto.setSentDate(message.getSentDate());
            }
            folder.close(false);
            store.close();
        } catch (NoSuchProviderException ex) {
            System.out.println("No provider.");
            ex.printStackTrace();
        } catch (MessagingException ex) {
            System.out.println("Could not connect to the message store");
            ex.printStackTrace();
        }

        return readDto;
    }

我的 Controller

    @GetMapping("/read")
    public String getEmails(Model model){
        ReadDto readDto = emailReadService.downloadEmails();
        model.addAttribute("emails", readDto);
        return READ_VIEW;
    }

在 View 中:

<div class="container">
    <div class="card-body">
        <table class="table table-striped table-dark">
            <thead>
            <tr>
                <th>From</th>
                <th>Subject</th>
                <th>Sent date</th>
                <th></th>
            </tr>
            </thead>
            <tbody>
            <tr th:each="readDto: ${emails}">
                <td><span th:text="${emails.from}"> From </span></td>
                <td><span th:text="${emails.subject}"> Subject </span></td>
                <td><span th:text="${emails.sentDate}"> Sent date </span></td>

            </tr>
            </tbody>
        </table>
    </div>
</div>

Answer 1

而不是这个:

<tr th:each="readDto: ${emails}">
    <td><span th:text="${emails.from}"> From </span></td>
    <td><span th:text="${emails.subject}"> Subject </span></td>
    <td><span th:text="${emails.sentDate}"> Sent date </span></td>
</tr>

您需要使用这个:

<tr th:each="readDto : ${emails}">
    <td><span th:text="${readDto.from}"> From </span></td>
    <td><span th:text="${readDto.subject}"> Subject </span></td>
    <td><span th:text="${readDto.sentDate}"> Sent date </span></td>
</tr>

readDto 变量代表 ${emails} 集合中的每个对象。

然后，在此之后，您需要确保从此处填充 readDTO 对象...

ReadDto readDto = emailReadService.downloadEmails();

...实际上是一个集合而不是单个对象。它需要是这样的:

public interface EmailReadService {
    List<ReadDto> downloadEmails();
}

现在，您的代码通过上述接口(interface)返回一封电子邮件:

for (Message message: messages){
    readDto.setFrom(Arrays.toString(message.getFrom()));
    readDto.setSubject(message.getSubject());
    readDto.setSentDate(message.getSentDate());
}

因此，您需要在创建这些 readDto 对象时将它们存储在列表中。