准备工作

开启SMTP服务

前往你的邮箱网站，以网易邮箱为例，打开网易邮箱地址，登录你的邮箱，进入邮箱管理后台界面。点击“设置”》》“POP3/SMTP/IMAP”后，点击开启SMTP服务即可。

技术实现

Spring Boot 发送邮件验证码的功能，主要用到了spring-boot-starter-mail工具包实现邮件的发送功能，利用junit-vintage-engine工具包实现了html邮件模板功能，利用easy-captcha工具包生成随机验证码 的功能！

引入依赖

     <!--引入mail依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-mail</artifactId>
        </dependency>
         <!--mail模板-->
         <dependency>
            <groupId>org.junit.vintage</groupId>
            <artifactId>junit-vintage-engine</artifactId>
            <scope>test</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.hamcrest</groupId>
                    <artifactId>hamcrest-core</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
          <!--验证码-->
        <dependency>
            <groupId>com.github.whvcse</groupId>
            <artifactId>easy-captcha</artifactId>
            <version>1.6.2</version>
        </dependency>

相关配置

然后再spring的配置文件中，设置mail相关配置：

spring:
  mail:
    host: smtp.yeah.com
    username: 你的邮箱
    password: 邮箱授权码
    default-encoding: UTF-8
    protocol: smtp
    properties:
      mail:
        smtp:
           auth: true # 启用SMTP认证
           starttls:
              enabled: true # 启用SMTP认证
              required: true # 必须采用加密链接

代码实现

创建一个MailService类，实现邮件发送的功能，代码如下：

import com.tarzan.nav.modules.admin.service.sys.SysConfigService;
import com.tarzan.nav.utils.DateUtil;
import lombok.extern.slf4j.Slf4j;
import org.antlr.stringtemplate.StringTemplate;
import org.antlr.stringtemplate.StringTemplateGroup;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.mail.javamail.JavaMailSender;
import org.springframework.mail.javamail.MimeMessageHelper;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Component;

import javax.annotation.Resource;
import javax.mail.MessagingException;
import javax.mail.internet.InternetAddress;
import javax.mail.internet.MimeMessage;
import javax.mail.internet.MimeUtility;
import java.io.UnsupportedEncodingException;
import java.util.Objects;


/**
 * @author lsyong
 */
@Component("mailService")
@Slf4j
public class MailService {

	private static final StringTemplateGroup templateGroup;
	@Resource
	private  SysConfigService sysConfigService;

	static{
		String classpath = Objects.requireNonNull(MailService.class.getClassLoader().getResource("")).getPath();
		templateGroup = new StringTemplateGroup("mailTemplates", classpath + "/mailTemplates");
	}
	
	public static String IMG_BASE_URL;
	public static String ACTIVATE_CONTEXT="http:";
	public static String RESET_PWD_CONTEXT;

	@Value("${spring.mail.username}")
	private String username;
    @Resource
    private JavaMailSender mailSender;


    private void sendMail(String to, String subject, String body) {
    	MimeMessage mail = mailSender.createMimeMessage();	
    	try {
    		MimeMessageHelper helper = new MimeMessageHelper(mail, true, "utf-8");
			helper.setFrom(new InternetAddress(MimeUtility.encodeText(sysConfigService.getSiteName())+"<"+username+">").toString());
			helper.setTo(to);
			helper.setSubject(subject);
			helper.setText(body, true);
			helper.setSentDate(DateUtil.now());
			mailSender.send(mail);
		} catch (MessagingException|UnsupportedEncodingException e) {
			log.error(e.getMessage());
		}
	}
    
    /**
     * send activation mail to
     * @param to,key
     */
    public void sendAccountActivationEmail(String to, String key){
    	StringTemplate activation_temp = templateGroup.getInstanceOf("activation");
    	activation_temp.setAttribute("img_base_url", IMG_BASE_URL);
    	activation_temp.setAttribute("email", to);
    	activation_temp.setAttribute("href", ACTIVATE_CONTEXT+key+"?email="+to);
    	activation_temp.setAttribute("link", ACTIVATE_CONTEXT+key+"?email="+to);
    	sendMail(to, sysConfigService.getSiteName()+"账户激活", activation_temp.toString());
    }

	@Async
	public void sendEmailCode(String to, String code){
		StringTemplate activation_temp = templateGroup.getInstanceOf("verificationCode");
		activation_temp.setAttribute("img_base_url", IMG_BASE_URL);
		activation_temp.setAttribute("email", to);
		activation_temp.setAttribute("code", code);
		sendMail(to, sysConfigService.getSiteName()+"邮箱验证码", activation_temp.toString());
	}
    
    /**
     * send change password link to
     * @param to,key
     */
    public void sendResetPwdEmail(String to, String key){
    	StringTemplate activation_temp = templateGroup.getInstanceOf("resetpwd");
    	activation_temp.setAttribute("img_base_url", IMG_BASE_URL);
    	activation_temp.setAttribute("href", RESET_PWD_CONTEXT+"?key="+key+"&email="+to);
    	activation_temp.setAttribute("link", RESET_PWD_CONTEXT+"?key="+key+"&email="+to);
    	sendMail(to, sysConfigService.getSiteName()+"账户密码重置", activation_temp.toString());
    }
}