新增mapper

+package com.yohoufo.dal.order;
+
+import com.yohoufo.dal.order.model.ExpressCompany;
+
+import java.util.List;
+
+/**
+ * @author kun.wang
+ * @date 2018/9/25
+ */
+public interface ExpressCompanyMapper {
+
+    /**
+     * 查询全部的快递公司信息
+     * @return
+     */
+    List<ExpressCompany> queryAllExpressCompany();
+}

+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
+<mapper namespace="com.yohoufo.dal.order.ExpressCompanyMapper">
+
+    <resultMap id="expressCompany" type="com.yohoufo.dal.order.model.ExpressCompany">
+        <id property="id" column="id"/>
+        <result property="companyName" column="company_name"/>
+    </resultMap>
+
+    <select id="queryAllExpressCompany" resultMap="expressCompany">
+        select id, company_name
+        from express_company
+    </select>
+
+</mapper>