refactor code

src/main/java/com/peanut/modules/book/service/ExpressCompanyService.java

@@ -0,0 +1,23 @@
+package com.peanut.modules.book.service;
+
+import com.baomidou.mybatisplus.extension.service.IService;
+import com.peanut.modules.book.entity.ExpressCompany;
+import com.peanut.modules.book.vo.ExpressCompanyVo;
+import org.springframework.stereotype.Service;
+
+import java.util.List;
+
+/**
+ * @Description: 快递公司服务层
+ * @Author: Cauchy
+ * @CreateTime: 2023/10/16
+ */
+@Service
+public interface ExpressCompanyService extends IService<ExpressCompany> {
+    /**
+     * 获取快递公司列表
+     *
+     * @return List
+     */
+    List<ExpressCompanyVo> getExpressCompanyList();
+}