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backend/src/main/java/com/example/demo/common/EmailSenderService.java

@@ -0,0 +1,57 @@
+package com.example.demo.common;
+
+import jakarta.mail.internet.MimeMessage;
+import org.springframework.beans.factory.annotation.Value;
+import org.springframework.mail.javamail.JavaMailSender;
+import org.springframework.mail.javamail.MimeMessageHelper;
+import org.springframework.stereotype.Service;
+
+@Service
+public class EmailSenderService {
+    private final JavaMailSender mailSender;
+    private final EmailProperties props;
+
+    @Value("${spring.mail.username:}")
+    private String mailUsername;
+
+    public EmailSenderService(JavaMailSender mailSender, EmailProperties props) {
+        this.mailSender = mailSender;
+        this.props = props;
+    }
+
+    public void sendPlainText(String to, String subject, String content) {
+        if (to == null || to.isBlank()) throw new IllegalArgumentException("收件人邮箱不能为空");
+        if (subject == null) subject = "";
+        if (content == null) content = "";
+        try {
+            MimeMessage message = mailSender.createMimeMessage();
+            MimeMessageHelper helper = new MimeMessageHelper(message, false, "UTF-8");
+            helper.setFrom(resolveFromAddress());
+            helper.setTo(to.trim());
+            helper.setSubject(composeSubject(subject));
+            helper.setText(content, false);
+            mailSender.send(message);
+        } catch (IllegalStateException | IllegalArgumentException e) {
+            throw e;
+        } catch (Exception e) {
+            throw new RuntimeException("发送邮件失败: " + e.getMessage(), e);
+        }
+    }
+
+    private String composeSubject(String subject) {
+        String prefix = props.getSubjectPrefix();
+        if (prefix == null || prefix.isBlank()) return subject;
+        return prefix + " " + subject;
+    }
+
+    private String resolveFromAddress() {
+        String from = props.getFrom();
+        if (from == null || from.isBlank()) from = mailUsername;
+        if (from == null || from.isBlank()) {
+            throw new IllegalStateException("邮件服务未配置，请设置 MAIL_USERNAME/MAIL_PASSWORD 以及 MAIL_FROM 或 spring.mail.username");
+        }
+        return from.trim();
+    }
+}
+
+