EmailConfig

EmailService

public class EmailService {
    public void sendEmail(
        if (siteConfig != null) {
            mailSender(siteConfig).send(mimeMessage);
        } else {
            this.javaMailSender.send(mimeMessage);
        }
    }

/*
* Using this method, configuration is updated on the fly when any change happens on DB
*/
    public JavaMailSender mailSender(SiteConfig siteConfig) {
        JavaMailSenderImpl mailSender = new JavaMailSenderImpl();
        mailSender.setHost(siteConfig.getSmtpHost());
        mailSender.setPort(siteConfig.getSmtpPort());
        mailSender.setUsername(siteConfig.getSmtpUsername());
        mailSender.setPassword(siteConfig.getSmtpPassword());
        Properties props = System.getProperties();
        props.put("mail.transport.protocol", "smtp");
        props.put("mail.smtp.auth", siteConfig.isSmtpAuth());
        props.put("mail.smtp.starttls.enable", siteConfig.isSmtpStartTlsEnable());
        props.put("mail.debug", siteConfig.isSmtpDebug());
        mailSender.setJavaMailProperties(props);
        return mailSender;
    }
}    

gistfile1.txt

package com.example.solution.config;

import com.example.solution.entity.SiteConfig;
import com.example.solution.service.SiteConfigService;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.JavaMailSenderImpl;

import java.util.Properties;
/*
* This is a configuration file which overrides SMTP configuration at start up of application
*/

@Configuration
@ConfigurationProperties
public class EmailConfig {

    private final SiteConfigService siteConfigService;


    public EmailConfig(SiteConfigService siteConfigService) {
        this.siteConfigService = siteConfigService;
    }

    @Bean
    public JavaMailSender getJavaMailSender() {
        JavaMailSenderImpl mailSender = new JavaMailSenderImpl();
        SiteConfig siteConfig = siteConfigService.findByName("main");
        if (siteConfig != null) {
            // Set up Gmail config
            mailSender.setHost(siteConfig.getSmtpHost());
            mailSender.setPort(siteConfig.getSmtpPort());

            mailSender.setUsername(siteConfig.getSmtpUsername());
            mailSender.setPassword(siteConfig.getSmtpPassword());

            Properties props = mailSender.getJavaMailProperties();
            props.put("mail.transport.protocol", "smtp");
            props.put("mail.smtp.auth", siteConfig.isSmtpAuth());
            props.put("mail.smtp.starttls.enable", siteConfig.isSmtpStartTlsEnable());
            props.put("mail.debug", siteConfig.isSmtpDebug());

            return mailSender;
        }
        return null;

    }
}