Scheduled Email Sending with Spring Boot, JavaMail, and HttpClient

The author was inspired by a JavaScript love‑confession example and decided to implement a similar feature using Java.

The project is a Maven‑based Spring Boot application that adds mail sending, HTTP client, and scheduling capabilities.

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.3.2.RELEASE</version>
</parent>
<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-mail</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context-support</artifactId>
    </dependency>
    <!-- httpclient dependency -->
    <dependency>
        <groupId>org.apache.httpcomponents</groupId>
        <artifactId>httpclient</artifactId>
        <version>4.5.12</version>
    </dependency>
</dependencies>
<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <configuration>
                <fork>true</fork>
            </configuration>
        </plugin>
    </plugins>
</build>

Before coding, the author enables POP3/SMTP service in the email provider and obtains an authorization code.

spring:
  mail:
    username: [email protected]  # your email address
    password: xxxxxxx        # SMTP/POP3/IMAP authorization code
    host: smtp.qq.com        # mail server address
    properties:
      mail:
        smtp:
          auth: true          # enable SMTP authentication
    port: 587

# recipient configuration
she:
  mail: [email protected]

The main application class activates scheduling:

@EnableScheduling
@SpringBootApplication
public class BiaoBaiApp {
    public static void main(String[] args) {
        SpringApplication.run(BiaoBaiApp.class, args);
    }
}

A SendMessage component uses JavaMailSender to send plain‑text emails and contains a static method that retrieves a random sentence from https://chp.shadiao.app/api.php via Apache HttpClient.

@Component
public class SendMessage {
    @Autowired
    private JavaMailSender mailSender;
    @Value("${spring.mail.username}")
    private String from;
    @Value("${she.mail}")
    private String[] sheMail;

    public void sendMessage(String subject, String message) {
        try {
            MimeMessage mimeMessage = mailSender.createMimeMessage();
            MimeMessageHelper helper = new MimeMessageHelper(mimeMessage);
            helper.setFrom(from);
            helper.setTo(sheMail);
            helper.setSubject(subject);
            helper.setText(message);
            mailSender.send(helper.getMimeMessage());
        } catch (MessagingException e) {
            e.printStackTrace();
        }
    }

    /** Remote fetch of the message */
    public static String getOneS() {
        try {
            HttpClient client = HttpClients.createDefault();
            HttpGet get = new HttpGet("https://chp.shadiao.app/api.php");
            HttpResponse response = client.execute(get);
            HttpEntity entity = response.getEntity();
            String responseString = EntityUtils.toString(entity, "utf-8");
            return responseString;
        } catch (IOException e) {
            throw new RuntimeException("Failed to fetch sentence from website");
        }
    }
}

A scheduled task runs daily at 17:20, obtains the sentence, and sends the email.

@Component
public class MyScheduled {
    @Autowired
    private SendMessage sendMessage;

    // Execute every day at 17:20
    @Scheduled(cron = "0 20 17 * * *")
    public void dsrw() {
        String message = sendMessage.getOneS();
        sendMessage.sendMessage("Message from QingCha DanZhou! ❤", message);
    }
}

After building the jar, the author suggests opening port 587 (and optionally HTTP/HTTPS ports) on the server, then running the application in the background on Linux with nohup java -jar your.jar >test.log & or scheduling it via Windows Task Scheduler. nohup java -jar your.jar >test.log & For a richer email appearance, the author provides an optional method to send HTML content.

public void sendHtmlMessage(String subject, String message) {
    try {
        MimeMessage mimeMessage = mailSender.createMimeMessage();
        MimeMessageHelper helper = new MimeMessageHelper(mimeMessage);
        helper.setFrom(from);
        helper.setTo(sheMail);
        helper.setSubject(subject);
        helper.setText(message, true); // true enables HTML
        mailSender.send(helper.getMimeMessage());
    } catch (MessagingException e) {
        e.printStackTrace();
    }
}

The full source code is shared via a Baidu Cloud link (https://pan.baidu.com/s/17z1Pjs1iP9CDd7IYuGohYA, extraction code: 4rxp) for readers to explore and improve.