Java秒杀简单设计二：数据库表和Dao层设计

Java秒杀简单设计二：数据库表Dao层设计

上一篇中搭建springboot项目环境和设计数据库表  https://www.cnblogs.com/taiguyiba/p/9791431.html

在此基础上设计数据库表Dao层代码

1.数据库表设计

项目涉及到两张表，seckill:秒杀库存表，success_killed:秒杀成功明细表

seckill:秒杀库存表

CREATE TABLE `seckill`  (
  `seckill_id` bigint() NOT NULL AUTO_INCREMENT COMMENT '商品库存ID',
  `name` varchar() CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '商品名称',
  `number` int() NOT NULL COMMENT '库存数量',
  `create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
  `start_time` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00' COMMENT '秒杀开始时间',
  `end_time` timestamp NOT NULL DEFAULT '0000-00-00 00:00:00' COMMENT '秒杀结束时间',
  PRIMARY KEY (`seckill_id`) USING BTREE,
  INDEX `idx_start_time`(`start_time`) USING BTREE,
  INDEX `idx_end_time`(`end_time`) USING BTREE,
  INDEX `idx_create_time`(`create_time`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT =  CHARACTER SET = utf8 COLLATE = utf8_general_ci COMMENT = '秒杀库存表';

插入数据：

INSERT INTO `seckill` VALUES (, '1000元秒杀iphone6', , '2018-10-14 22:36:57', '2016-01-01 00:00:00', '2016-01-02 00:00:00');
INSERT INTO `seckill` VALUES (, '800元秒杀ipad', , '2018-10-14 22:36:57', '2016-01-01 00:00:00', '2016-01-02 00:00:00');
INSERT INTO `seckill` VALUES (, '6600元秒杀mac book pro', , '2018-10-14 22:36:57', '2016-01-01 00:00:00', '2016-01-02 00:00:00');
INSERT INTO `seckill` VALUES (, '7000元秒杀iMac', , '2018-10-14 22:36:57', '2016-01-01 00:00:00', '2016-01-02 00:00:00');

success_killed:秒杀成功明细表

CREATE TABLE `success_killed`  (
  `seckill_id` bigint() NOT NULL COMMENT '秒杀商品ID',
  `user_phone` bigint() NOT NULL COMMENT '用户手机号',
  `state` tinyint() NOT NULL DEFAULT - COMMENT '状态标识:-1:无效 0:成功 1:已付款 2:已发货',
  `create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '创建时间',
  PRIMARY KEY (`seckill_id`, `user_phone`) USING BTREE,
  INDEX `idx_create_time`(`create_time`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci COMMENT = '秒杀成功明细表';

2.Dao设计

首先在 SeckillApplication.java文件中添加Mapper扫描注解@MapperScan("com.seckill.dao")

package com.seckill;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan("com.seckill.dao")
public class SeckillApplication {

    public static void main(String[] args) {
        SpringApplication.run(SeckillApplication.class, args);
    }
}

创建SeckillDao.java文件：

包括减库存、查询、使用存储过程秒杀等方法

package com.seckill.dao;

import java.util.Date;
import java.util.List;
import java.util.Map;

import org.apache.ibatis.annotations.Param;

import com.seckill.entity.Seckill;

public interface SeckillDao {

    /**
     * 减库存
     * @param seckillId
     * @param killTime
     * @return 如果影响行数>1，表示更新库存的记录行数
     */
    int reduceNumber(@Param("seckillId") long seckillId,@Param("killTime") Date killTime);
    /**
     * 根据id查询秒杀的商品信息
     * @param seckillId
     * @return
     */
    Seckill queryById(@Param("seckillId") long seckillId);
    /**
     * 根据偏移量查询秒杀商品列表
     * @param offset
     * @param limit
     * @return
     */
    List<Seckill> queryAll(@Param("offset") int offset,@Param("limit")int limit);
    /**
     * 使用存储过程执行秒杀
     * @param paramMap
     */
    void killByProcedure(Map<String,Object> paramMap);

}

 注意：Java没有保存形参的记录，queryAll(int offset,int limit) ==> queryAll(arg0,arg1),所以在多个参数的时候，需要使用注解：@Param

创建 SuccessKilledDao.java文件

package com.seckill.dao;

import org.apache.ibatis.annotations.Param;

import com.seckill.entity.SuccessKilled;

public interface SuccessKilledDao {

    /**
     * 插入购买明细，可过滤重复
     * @param seckillId
     * @param userPhone
     * @return 插入的行数
     */
    int insertSuccessKilled(@Param("seckillId") long seckillId,@Param("userPhone") long userPhone);
    /**
     * 根据秒杀商品ID查询明细SuccessKilled对象， 携带了Seckill秒杀产品对象
     * @param seckillId
     * @param userPhone
     * @return
     */
    SuccessKilled queryByIdWithSeckill(@Param("seckillId") long seckillId,@Param("userPhone") long userPhone);
}

创建SeckillDao.xml文件

<?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.seckill.dao.SeckillDao">
    <update id="reduceNumber">
        UPDATE seckill
        SET number = number -
        WHERE seckill_id = #{seckillId}
        AND start_time <![CDATA[ <= ]]> #{killTime}
        AND end_time >= #{killTime}
        AND number >
    </update>

    <select id="queryById" resultType="Seckill" parameterType="long">
        SELECT *
        FROM seckill
        WHERE seckill_id = #{seckillId}
    </select>

    <select id="queryAll" resultType="Seckill">
        SELECT *
        FROM seckill
        ORDER BY create_time DESC
        limit #{offset},#{limit}
    </select>
    <!-- 使用mybatis调用存储过程 -->
    <select id="killByProcedure" statementType="CALLABLE">
        call execute_seckill(
            #{seckillId,jdbcType=BIGINT,mode=IN},
            #{phone,jdbcType=BIGINT,mode=IN},
            #{killTime,jdbcType    =TIMESTAMP,mode=IN},
            #{result,jdbcType=INTEGER,mode=OUT}
        )
    </select>
</mapper>

SuccessKilledDao.xml文件

<?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.seckill.dao.SuccessKilledDao">
    <insert id="insertSuccessKilled">
        <!--当出现主键冲突时(即重复秒杀时)，会报错;不想让程序报错，加入ignore-->
        INSERT ignore INTO success_killed(seckill_id,user_phone,state)
        VALUES (#{seckillId},#{userPhone},0)
    </insert>

    <select id="queryByIdWithSeckill" resultType="SuccessKilled">
        <!--根据seckillId查询SuccessKilled对象，并携带Seckill对象-->
        <!--如何告诉mybatis把结果映射到SuccessKill属性同时映射到Seckill属性-->
        <!--可以自由控制SQL语句-->
        SELECT
            sk.seckill_id,
            sk.user_phone,
            sk.create_time,
            sk.state,
            s.seckill_id "seckill.seckill_id",
            s.name "seckill.name",
            s.number "seckill.number",
            s.start_time "seckill.start_time",
            s.end_time "seckill.end_time",
            s.create_time "seckill.create_time"
        FROM success_killed sk
        INNER JOIN seckill s ON sk.seckill_id = s.seckill_id
        WHERE sk.seckill_id=#{seckillId} and sk.user_phone=#{userPhone}
    </select>
</mapper>