fix: 优化邮件发送服务

- 邮件发送者名称设置为"AIOJ"
- 添加UnsupportedEncodingException异常处理
- 新增RedisKeyConstants常量类统一管理Redis Key

Co-Authored-By: Claude <noreply@anthropic.com>

aioj-backend-user-service/src/main/java/cn/meowrain/aioj/backend/userservice/common/constants/RedisKeyConstants.java

@@ -0,0 +1,16 @@
+package cn.meowrain.aioj.backend.userservice.common.constants;
+
+/**
+ * Redis Key 常量对象 - user-service
+ */
+public class RedisKeyConstants {
+    /**
+     * 邮箱验证码存储 Key 格式: email:code:{email}
+     */
+    public static final String EMAIL_CODE_PREFIX = "email:code:%s";
+
+    /**
+     * 邮箱验证码有效期 (秒) - 1分钟
+     */
+    public static final long EMAIL_CODE_TTL = 60;
+}

aioj-backend-user-service/src/main/java/cn/meowrain/aioj/backend/userservice/service/impl/EmailServiceImpl.java

@@ -13,6 +13,7 @@ import org.springframework.mail.javamail.JavaMailSender;
 import org.springframework.mail.javamail.MimeMessageHelper;
 import org.springframework.stereotype.Service;
 
+import java.io.UnsupportedEncodingException;
 import java.security.SecureRandom;
 import java.util.concurrent.TimeUnit;
 
@@ -107,7 +108,7 @@ public class EmailServiceImpl implements EmailService {
             MimeMessage message = mailSender.createMimeMessage();
             // ⭐ 显式指定 UTF-8 编码，解决中文乱码问题
             MimeMessageHelper helper = new MimeMessageHelper(message, true, "UTF-8");
-            helper.setFrom(FROM_EMAIL);
+            helper.setFrom(FROM_EMAIL,"AIOJ");
             helper.setTo(email);
             helper.setSubject(SUBJECT);
             helper.setText(buildEmailContent(code), true);
@@ -118,6 +119,8 @@ public class EmailServiceImpl implements EmailService {
         }catch (MessagingException e) {
             log.error("验证码邮件发送失败: 邮箱={}", email, e);
             throw new ServiceException("邮件发送失败,请稍后重试");
+        } catch (UnsupportedEncodingException e) {
+            throw new ServiceException("邮件发送失败,请稍后重试");
         }
     }