java 下载邮件附件

以下是使用Java下载邮件附件的示例代码：

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Properties;

import javax.mail.BodyPart;
import javax.mail.Folder;
import javax.mail.Message;
import javax.mail.MessagingException;
import javax.mail.Multipart;
import javax.mail.Session;
import javax.mail.Store;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMultipart;
import javax.mail.internet.MimeUtility;

public class EmailAttachmentDownloader {
    public static void main(String[] args) {
        String host = "your_host";
        String username = "your_username";
        String password = "your_password";
        String folderName = "INBOX";
        String saveDirectory = "path_to_save_directory";

        Properties properties = new Properties();
        properties.put("mail.store.protocol", "imaps");

        try {
            Session session = Session.getDefaultInstance(properties, null);
            Store store = session.getStore();
            store.connect(host, username, password);

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

            Message[] messages = folder.getMessages();

            for (int i = 0; i < messages.length; i++) {
                Message message = messages[i];
                Multipart multipart = (Multipart) message.getContent();

                for (int j = 0; j < multipart.getCount(); j++) {
                    BodyPart bodyPart = multipart.getBodyPart(j);
                    if (bodyPart instanceof MimeBodyPart) {
                        MimeBodyPart mimeBodyPart = (MimeBodyPart) bodyPart;
                        if (MimeUtility.isAttachment(mimeBodyPart)) {
                            String fileName = MimeUtility.decodeText(mimeBodyPart.getFileName());
                            File file = new File(saveDirectory + File.separator + fileName);
                            FileOutputStream fos = new FileOutputStream(file);
                            mimeBodyPart.saveFile(file);
                            fos.close();
                        }
                    }
                }
            }

            folder.close(false);
            store.close();
        } catch (MessagingException | IOException e) {
            e.printStackTrace();
        }
    }
}

请注意，您需要将代码中的"your_host"，"your_username"，"your_password"和"path_to_save_directory"替换为您自己的实际值。