使用java mail api读取电子邮件时出现字符编码问题

import javax.mail.*;
import javax.mail.internet.*;
import java.nio.charset.Charset;
import java.util.Properties;

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

        // 创建会话
        Properties props = new Properties();
        props.setProperty("mail.store.protocol", "imaps");
        Session session = Session.getInstance(props);

        // 连接到邮箱
        Store store = session.getStore();
        store.connect(host, username, password);

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

        // 获取邮件列表
        Message[] messages = inbox.getMessages();

        // 遍历邮件并解析内容
        for (Message message : messages) {
            String subject = message.getSubject();
            String from = InternetAddress.toString(message.getFrom());
            String content = getTextFromMessage(message);

            // 处理邮件内容的逻辑
            // ...

            System.out.println("Subject: " + subject);
            System.out.println("From: " + from);
            System.out.println("Content: " + content);
        }

        // 关闭连接
        inbox.close(false);
        store.close();
    }

    private static String getTextFromMessage(Message message) throws Exception {
        if (message.isMimeType("text/plain")) {
            return message.getContent().toString();
        } else if (message.isMimeType("multipart/*")) {
            MimeMultipart mimeMultipart = (MimeMultipart) message.getContent();
            return getTextFromMimeMultipart(mimeMultipart);
        }
        return "";
    }

    private static String getTextFromMimeMultipart(MimeMultipart mimeMultipart) throws Exception {
        StringBuilder result = new StringBuilder();
        int count = mimeMultipart.getCount();
        for (int i = 0; i < count; i++) {
            BodyPart bodyPart = mimeMultipart.getBodyPart(i);
            if (bodyPart.isMimeType("text/plain")) {
                result.append(bodyPart.getContent());
                break; // 只获取第一个文本部分
            } else if (bodyPart.isMimeType("text/html")) {
                String html = (String) bodyPart.getContent();
                result.append(html);
            } else if (bodyPart.getContent() instanceof MimeMultipart) {
                result.append(getTextFromMimeMultipart((MimeMultipart) bodyPart.getContent()));
            }
        }
        return result.toString();
    }
}