Optimizing Java Email Sending: Tips and Practical Methods to Improve Email Transmission Efficiency

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

public class EmailSender {
    public static void main(String[] args) {
        // 配置SMTP服务器信息
        Properties props = new Properties();
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.host", "smtp.example.com");
        props.put("mail.smtp.port", "587");

        // 创建会话
        Session session = Session.getDefaultInstance(props,
            new javax.mail.Authenticator() {
                protected PasswordAuthentication getPasswordAuthentication() {
                    return new PasswordAuthentication("your_username", "your_password");
                }
            });

        try {
            // 创建邮件消息
            Message message = new MimeMessage(session);
            message.setFrom(new InternetAddress("sender@example.com"));
            message.setRecipients(Message.RecipientType.TO,
                InternetAddress.parse("recipient@example.com"));
            message.setSubject("邮件标题");
            message.setText("邮件正文");

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

            System.out.println("邮件发送成功！");
        } catch (MessagingException e) {
            System.out.println("邮件发送失败：" + e.getMessage());
        }
    }
}

import org.apache.commons.pool2.ObjectPool;
import org.apache.commons.pool2.impl.GenericObjectPool;
import javax.mail.*;

public class ConnectionPool {
    private static final int MAX_CONNECTIONS = 10;
    private static final String SMTP_HOST = "smtp.example.com";
    private static final int SMTP_PORT = 587;
    private static final String USER_NAME = "your_username";
    private static final String PASSWORD = "your_password";

    public static void main(String[] args) {
        Properties props = new Properties();
        props.put("mail.smtp.auth", "true");
        props.put("mail.smtp.host", SMTP_HOST);
        props.put("mail.smtp.port", SMTP_PORT);

        GenericObjectPool<Transport> pool = new GenericObjectPool<>(new TransportFactory(props, USER_NAME, PASSWORD));
        pool.setMaxTotal(MAX_CONNECTIONS);

        try {
            Transport transport = pool.borrowObject();

            Message message = new MimeMessage(Session.getDefaultInstance(props, null));
            // 设置邮件消息...

            transport.sendMessage(message, message.getAllRecipients());

            pool.returnObject(transport);

            System.out.println("邮件发送成功！");
        } catch (Exception e) {
            System.out.println("邮件发送失败：" + e.getMessage());
        }
    }
}

class TransportFactory extends BasePooledObjectFactory<Transport> {
    private final Properties properties;
    private final String userName;
    private final String password;

    public TransportFactory(Properties properties, String userName, String password) {
        this.properties = properties;
        this.userName = userName;
        this.password = password;
    }

    @Override
    public Transport create() throws Exception {
        Session session = Session.getInstance(properties, new Authenticator() {
            @Override
            protected PasswordAuthentication getPasswordAuthentication() {
                return new PasswordAuthentication(userName, password);
            }
        });
        return session.getTransport();
    }

    @Override
    public PooledObject<Transport> wrap(Transport transport) {
        return new DefaultPooledObject<>(transport);
    }

    @Override
    public void destroyObject(PooledObject<Transport> p) throws Exception {
        p.getObject().close();
    }
}