用java语言给需要付款的人发送邮件：您有订单待支付，请及时处理；如果发送三次依然没有支付，则取消该订单

可以使用JavaMail API来实现给需要付款的人发送邮件。以下是一个简单的示例代码：

import java.util.Properties;
import javax.mail.*;
import javax.mail.internet.*;

public class PaymentReminder {
    public static void main(String[] args) {
        final String username = "your_email@example.com";
        final String password = "your_email_password";

        Properties props = new Properties();
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.starttls.enable", "true");
        props.put("mail.smtp.host", "smtp.example.com");
        props.put("mail.smtp.port", "587");

        Session session = Session.getInstance(props,
          new javax.mail.Authenticator() {
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(username, password);
            }
          });

        try {
            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress("your_email@example.com"));
            message.setRecipients(Message.RecipientType.TO,
                InternetAddress.parse("recipient_email@example.com"));
            message.setSubject("Payment Reminder");
            message.setText("Dear customer,"
                + "\n\nYou have an order waiting for payment. Please process it as soon as possible. If the payment is not received after three reminders, the order will be cancelled.");

            Transport.send(message);

            System.out.println("Payment reminder email sent successfully!");

        } catch (MessagingException e) {
            throw new RuntimeException(e);
        }
    }
}

在上面的代码中，需要将`your_email@example.com`和`your_email_password`替换为你自己的邮箱地址和密码，将`smtp.example.com`替换为你的SMTP服务器地址。同时，需要将`recipient_email@example.com`替换为需要发送邮件的收件人邮箱地址。

当你运行这个程序时，它将会发送一封邮件给收件人，提醒他们有一个订单需要支付。如果三次提醒后仍未支付，订单将会被取消。