feat: register logic refactor

src/main/java/xin/merlin/myplayerbackend/service/MailService.java

@@ -0,0 +1,36 @@
+package xin.merlin.myplayerbackend.service;
+
+import lombok.RequiredArgsConstructor;
+import lombok.extern.slf4j.Slf4j;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.mail.MailException;
+import org.springframework.mail.SimpleMailMessage;
+import org.springframework.mail.javamail.JavaMailSender;
+import org.springframework.stereotype.Service;
+
+@Slf4j
+@Service
+@RequiredArgsConstructor
+public class MailService {
+
+    private final JavaMailSender mailSender;
+
+    @Value("${spring.mail.username}")
+    private String mail;
+
+    public String sendMail(String receiver){
+        try {
+            String code = Double.toString(Math.random()).substring(2,8);
+            SimpleMailMessage message = new SimpleMailMessage();
+            message.setFrom(mail);
+            message.setTo(receiver);
+            message.setSubject("Welcome to use Merlin`s product");
+            message.setText("欢迎使用Merlin.xin产品！ \n"+"您的验证码为："+code+"\n有效期五分钟，请勿泄露！");
+            mailSender.send(message);
+            return code;
+        } catch (MailException e) {
+            log.error("e: ", e);
+            throw new RuntimeException(e);
+        }
+    }
+}