java发送邮件带附件

好的，以下是 Java 发送带附件的邮件的示例代码：

import java.util.Properties;
import javax.mail.Authenticator;
import javax.mail.Message;
import javax.mail.PasswordAuthentication;
import javax.mail.Session;
import javax.mail.Transport;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeBodyPart;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeMultipart;
import javax.mail.internet.MimeUtility;

public class SendEmailWithAttachment {
    public static void main(String[] args) throws Exception {
        // 邮件配置
        String host = "smtp.163.com"; // SMTP 服务器地址
        int port = 25; // SMTP 服务器端口
        String username = "your_email@163.com"; // 发件人邮箱账号
        String password = "your_email_password"; // 发件人邮箱密码
        String from = "your_email@163.com"; // 发件人邮箱地址
        String to = "recipient_email@example.com"; // 收件人邮箱地址
        String subject = "邮件主题";
        String text = "邮件正文";

        // 创建邮件会话
        Properties props = new Properties();
        props.put("mail.smtp.host", host);
        props.put("mail.smtp.port", port);
        props.put("mail.smtp.auth", "true");
        Session session = Session.getDefaultInstance(props, new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(username, password);
            }
        });

        // 创建邮件消息
        MimeMessage message = new MimeMessage(session);
        message.setFrom(new InternetAddress(from));
        message.setRecipients(Message.RecipientType.TO, InternetAddress.parse(to));
        message.setSubject(subject);

        // 创建邮件正文
        MimeBodyPart textPart = new MimeBodyPart();
        textPart.setContent(text, "text/plain;charset=UTF-8");

        // 创建邮件附件
        MimeBodyPart attachmentPart = new MimeBodyPart();
        String attachmentFilePath = "attachment.txt"; // 附件文件路径
        attachmentPart.attachFile(attachmentFilePath);
        attachmentPart.setFileName(MimeUtility.encodeText(attachmentPart.getFileName()));

        // 创建邮件多部分内容
        MimeMultipart multipart = new MimeMultipart();
        multipart.addBodyPart(textPart);
        multipart.addBodyPart(attachmentPart);
        message.setContent(multipart);

        // 发送邮件
        Transport.send(message);

        System.out.println("邮件发送成功");
    }
}

其中，需要将 `host`、`port`、`username`、`password`、`from`、`to`、`subject`、`text` 和 `attachmentFilePath` 替换为实际的值。

需要注意的是，附件文件路径需要使用绝对路径，并且需要保证附件文件存在。另外，为了避免中文文件名乱码，需要使用 `MimeUtility.encodeText()` 方法对附件文件名进行编码。