Java Email Sending Utility Using Spring and JavaMail

The post shares a complete Java tutorial for sending emails via SMTP using Spring and the JavaMail library. It begins with the required Maven dependency for javax.mail:

<!-- javax.mail -->
<dependency>
    <groupId>com.sun.mail</groupId>
    <artifactId>javax.mail</artifactId>
    <version>1.6.0</version>
</dependency>

Next, the necessary SMTP configuration properties are listed, which should be placed in the application’s configuration file:

mail.smtp.auth=true
mail.transport.protocol=smtp
mail.send.charset=UTF-8
mail.smtp.port=465
mail.is.ssl=true
mail.host=smtp.163.com
[email protected]
mail.auth.password=
mail.smtp.timeout=5000

The core of the tutorial is the EmailUtils component. It reads the above properties at startup, builds a JavaMailSenderImpl instance, and provides a static sendEmail method that supports multiple recipients, CC, HTML content, and file attachments. The implementation handles SSL socket factories, constructs a MimeMessage, and logs any failures.

package cn.aduu.utils;

import com.sun.mail.util.MailSSLSocketFactory;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.env.Environment;
import org.springframework.mail.javamail.JavaMailSenderImpl;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.springframework.stereotype.Component;

import javax.annotation.PostConstruct;
import javax.mail.internet.MimeMessage;
import java.io.File;
import java.security.GeneralSecurityException;
import java.util.List;
import java.util.Map;
import java.util.Properties;

/**
 * Email utility class for sending messages.
 */
@Component
public class EmailUtils {
    private static final Logger logger = LoggerFactory.getLogger(EmailUtils.class);

    @Autowired
    private Environment env;

    private static String auth;
    private static String host;
    private static String protocol;
    private static int port;
    private static String authName;
    private static String password;
    private static boolean isSSL;
    private static String charset;
    private static String timeout;

    @PostConstruct
    public void initParam() {
        auth = env.getProperty("mail.smtp.auth");
        host = env.getProperty("mail.host");
        protocol = env.getProperty("mail.transport.protocol");
        port = env.getProperty("mail.smtp.port", Integer.class);
        authName = env.getProperty("mail.auth.name");
        password = env.getProperty("mail.auth.password");
        charset = env.getProperty("mail.send.charset");
        isSSL = env.getProperty("mail.is.ssl", Boolean.class);
        timeout = env.getProperty("mail.smtp.timeout");
    }

    /**
     * Send an email.
     * @param subject   Email subject
     * @param toUsers   Recipients
     * @param ccUsers   CC recipients (optional)
     * @param content   HTML content
     * @param attachfiles List of attachments (name & file path)
     */
    public static boolean sendEmail(String subject, String[] toUsers, String[] ccUsers,
                                    String content, List<Map<String, String>> attachfiles) {
        boolean flag = true;
        try {
            JavaMailSenderImpl javaMailSender = new JavaMailSenderImpl();
            javaMailSender.setHost(host);
            javaMailSender.setUsername(authName);
            javaMailSender.setPassword(password);
            javaMailSender.setDefaultEncoding(charset);
            javaMailSender.setProtocol(protocol);
            javaMailSender.setPort(port);

            Properties properties = new Properties();
            properties.setProperty("mail.smtp.auth", auth);
            properties.setProperty("mail.smtp.timeout", timeout);
            if (isSSL) {
                MailSSLSocketFactory sf = null;
                try {
                    sf = new MailSSLSocketFactory();
                    sf.setTrustAllHosts(true);
                    properties.put("mail.smtp.ssl.enable", "true");
                    properties.put("mail.smtp.ssl.socketFactory", sf);
                } catch (GeneralSecurityException e) {
                    e.printStackTrace();
                }
            }
            javaMailSender.setJavaMailProperties(properties);

            MimeMessage mailMessage = javaMailSender.createMimeMessage();
            MimeMessageHelper messageHelper = new MimeMessageHelper(mailMessage, true);
            messageHelper.setTo(toUsers);
            if (ccUsers != null && ccUsers.length > 0) {
                messageHelper.setCc(ccUsers);
            }
            messageHelper.setFrom(authName);
            messageHelper.setSubject(subject);
            messageHelper.setText(content, true);

            if (attachfiles != null && attachfiles.size() > 0) {
                for (Map<String, String> attachfile : attachfiles) {
                    String attachfileName = attachfile.get("name");
                    File file = new File(attachfile.get("file"));
                    messageHelper.addAttachment(attachfileName, file);
                }
            }
            javaMailSender.send(mailMessage);
        } catch (Exception e) {
            logger.error("发送邮件失败!", e);
            flag = false;
        }
        return flag;
    }
}

To verify the utility, a simple Spring REST controller is provided. Calling the /sendEmail endpoint triggers EmailUtils.sendEmail with a test HTML message.

package cn.aduu.web;

import cn.aduu.utils.EmailUtils;
import com.fasterxml.jackson.core.JsonProcessingException;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

/**
 * Test controller for sending email.
 */
@RestController
public class EmailController {
    private static final Logger logger = LoggerFactory.getLogger(EmailController.class);

    @RequestMapping("sendEmail")
    public String sendEmail() throws JsonProcessingException {
        boolean isSend = EmailUtils.sendEmail(
                "这是一封测试邮件",
                new String[]{"[email protected]"},
                null,
                "<h3><a href='http://www.baidu.com'>百度一下，你就知道</a></h3>",
                null);
        return "发送邮件:" + isSend;
    }
}

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