获取集合

List list();

	<mapper namespace="com.hd.dao.DeviceMapper">
		<!--id: 对应java方法名-->
		<!--resultType： 对应java方法返回类型-->
	    <select id="list" resultType="Device">
	        select * from   tb_device
	    </select>
	</mapper>

获取对象

User findUserByName(String name);

	<mapper namespace="com.hd.dao.UserMapper">
		<!--parameterType: 参数类型-->
	    <select id="findUserByName" parameterType="String" resultType="User">
	        select * from  tb_user where name = #{name}
	    </select>
	</mapper>

Mybatis mapper.xml