JavaMail -如何读取实际的消息内容，而不是"javax.mail.internet.MimeMultipart“

import javax.mail.*;
import javax.mail.internet.*;

public class ReadEmail {
    public static void main(String[] args) {
        // 邮箱配置
        String host = "your_host";
        String username = "your_username";
        String password = "your_password";

        try {
            // 创建会话
            Properties props = new Properties();
            props.setProperty("mail.imap.host", host);
            props.setProperty("mail.imap.port", "993");
            props.setProperty("mail.imap.ssl.enable", "true");
            Session session = Session.getInstance(props);

            // 连接邮箱
            Store store = session.getStore("imap");
            store.connect(host, username, password);

            // 打开收件箱
            Folder inbox = store.getFolder("INBOX");
            inbox.open(Folder.READ_ONLY);

            // 获取邮件消息
            Message[] messages = inbox.getMessages();

            // 遍历消息
            for (Message message : messages) {
                // 获取消息内容
                Object content = message.getContent();

                // 判断消息类型
                if (content instanceof String) {
                    // 简单文本消息
                    String text = (String) content;
                    System.out.println("Text: " + text);
                } else if (content instanceof Multipart) {
                    // 复杂消息
                    Multipart multipart = (Multipart) content;
                    for (int i = 0; i < multipart.getCount(); i++) {
                        BodyPart bodyPart = multipart.getBodyPart(i);
                        if (bodyPart.isMimeType("text/plain")) {
                            // 文本部分
                            String text = (String) bodyPart.getContent();
                            System.out.println("Text: " + text);
                        } else if (bodyPart.isMimeType("text/html")) {
                            // HTML部分
                            String html = (String) bodyPart.getContent();
                            System.out.println("HTML: " + html);
                        } else if (bodyPart instanceof MimeBodyPart) {
                            // 附件部分
                            MimeBodyPart mimeBodyPart = (MimeBodyPart) bodyPart;
                            System.out.println("Attachment: " + mimeBodyPart.getFileName());
                        }
                    }
                }
            }

            // 关闭连接
            inbox.close(false);
            store.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}