基于SpringMVC+Spring+MyBatis实现秒杀系统【数据库接口】

前言

       该篇教程主要关注MyBatis实现底层的接口，把MyBatis交给Spring来托管。数据库连接池用的c3p0。数据库用的MySQL。主要有2个大类：秒杀商品的查询、秒杀明细的插入。

准备工作

      1、数据库脚本。先初始化数据库，这里主要有2张表：seckill【秒杀商品表】、success_killed【秒杀记录明细表】。success_killed采用双主键seckill_id、user_phone。同一个商品同一个手机号只能秒杀一次，如果通过非法手段通过业务接口的话，则重复插入秒杀记录明细时会返回0。

-- 创建数据库
CREATE DATABASE seckill;
-- 使用数据库
use seckill;
CREATE TABLE seckill(
`seckill_id` BIGINT NOT NUll AUTO_INCREMENT COMMENT '商品库存ID',
`name` VARCHAR(120) NOT NULL COMMENT '商品名称',
`number` int NOT NULL COMMENT '库存数量',
`start_time` TIMESTAMP  NOT NULL COMMENT '秒杀开始时间',
`end_time`   TIMESTAMP   NOT NULL COMMENT '秒杀结束时间',
`create_time` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间',
PRIMARY KEY (seckill_id),
key idx_start_time(start_time),
key idx_end_time(end_time),
key idx_create_time(create_time)
)ENGINE=INNODB AUTO_INCREMENT=1000 DEFAULT CHARSET=utf8 COMMENT='秒杀库存表';

-- 初始化数据
INSERT into seckill(name,number,start_time,end_time)
VALUES
('1000元秒杀iphone6',100,'2016-01-01 00:00:00','2016-01-02 00:00:00'),
('800元秒杀ipad',200,'2016-01-01 00:00:00','2016-01-02 00:00:00'),
('6600元秒杀mac book pro',300,'2016-01-01 00:00:00','2016-01-02 00:00:00'),
('7000元秒杀iMac',400,'2016-01-01 00:00:00','2016-01-02 00:00:00');

-- 秒杀成功明细表
-- 用户登录认证相关信息(简化为手机号)
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 -1 COMMENT '状态标识:-1:无效 0:成功 1:已付款 2:已发货',
`create_time` TIMESTAMP NOT NULL COMMENT '创建时间',
PRIMARY KEY(seckill_id,user_phone),/*联合主键*/
KEY idx_create_time(create_time)
)ENGINE=INNODB DEFAULT CHARSET=utf8 COMMENT='秒杀成功明细表';

　  2、实现MyBatis配置文件并且交由Spring托管

mybatis-config.xml

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE configuration
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
<settings>
<!--使用jdbc的getGeneratedKeys获取自增主键值-->
<setting name="useGeneratedKeys" value="true"/>
<!--使用列别名替换列名，默认值true-->
<setting name="useColumnLabel" value="true"/>
<!--开启驼峰命名法 字段名seckill_Id 对应属性名seckillId -->
<setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>
</configuration>

spring-dao.xml

   这里关键是sqlsessionfactory的配置，需要指定mybatis全局配置文件、mapper.xml文件位置。

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd">

<!--1、配置数据库相关参数-->
<context:property-placeholder location="classpath:jdbc.properties"/>

<!--2、配置数据库连接池-->
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
<property name="driverClass" value="${jdbc.driver}"/>
<property name="jdbcUrl" value="${jdbc.url}"/>
<property name="user" value="${jdbc.username}"/>
<property name="password" value="${jdbc.password}"/>

<!--数据库连接池最大连接数-->
<property name="maxPoolSize" value="30" />
<!--数据库连接池最小连接数-->
<property name="minPoolSize" value="10"/>
<!--关闭连接后不自动commit-->
<property name="autoCommitOnClose" value="false"/>
<!--获取连接超时时间-->
<property name="checkoutTimeout" value="1000"/>
<!--当获取连接失败时重试次数-->
<property name="acquireRetryAttempts" value="3"/>
</bean>

<!--3、配置SqlSessionFactory-->
<bean id="sessionfactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<property name="dataSource" ref="dataSource"/>
<!--mybatis全局配置文件-->
<property name="configLocation" value="classpath:mybatis-config.xml"/>
<!--扫描entity包-->
<property name="typeAliasesPackage" value="com.seckill.entity"/>
<!--扫描sql xml文件-->
<property name="mapperLocations" value="classpath:mapper/*.xml"/>
</bean>

<!--4、配置扫描Dao接口包，动态实现dao接口注入到spring容器-->
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<!--需要扫描的dao接口-->
<property name="basePackage" value="com.seckill.dao"/>
<!--注入sqlsessionfactory-->
<property name="sqlSessionFactoryBeanName" value="sessionfactory"/>
</bean>
</beans>

秒杀底层接口实现

1、实现接口。这里注意Param注解，当方法只有一个参数时不用指定，如果你需要给mapper里传多个参数则指定，也可以用HashMap传参。

public interface SeckillDao {

/**减库存**/
int reduceNumber(@Param("seckillId") long seckillId,@Param("killTime") Date killTime);

/**查询秒杀商品详情**/
Seckill queryById(long seckillId);

/**查询所有秒杀商品**/
List<Seckill> queryAll(@Param("offset") int offset,@Param("limit") int limit);

}

public interface SuccessKillDao {

/**
* 插入秒杀商品明细
* **/
int insertSuccessKilled(@Param("seckillId") long seckillId,@Param("userPhone")  long userPhone);

/**
* 根据商品id查询商品秒杀明细，并且同时返回商品明细
* **/
SuccessKilled queryByIdWithSeckill(@Param("seckillId") long seckillId,@Param("userPhone")  long userPhone);

}

2、秒杀实现。也就是mapper目录下的*.xml文件。

SeckillDao.xml

<?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-1
where seckill_Id=#{seckillId}
and start_time <![CDATA[ <= ]]> #{killTime}
and end_time <![CDATA[ >= ]]> #{killTime}
and number>0
</update>

<select id="queryById" resultType="Seckill">
select seckill_id,name,number,start_time,end_time,create_time
from seckill
where seckill_id=#{seckillId}
</select>

<select id="queryAll" resultType="Seckill">
select seckill_id,name,number,start_time,end_time,create_time
from seckill
order by create_time
limit #{offset},#{limit}
</select>
</mapper>

SuccessKillDao.xml

<?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.SuccessKillDao">

<!--主键重复时不再插入数据-->
<insert id="insertSuccessKilled">

insert ignore into  success_killed (seckill_id,user_Phone,state) values (#{seckillId},#{userPhone},0)
</insert>

<select id="queryByIdWithSeckill" resultType="SuccessKilled">
select
sk.seckill_id,
sk.user_Phone,
sk.state,
sk.create_time,
s.seckill_id "seckill.seckill_id",
s.name "seckill.name",
s.number "seckill.number",
s.create_time "seckill.create_time",
s.start_time "seckill.start_time",
s.end_time "seckill.end_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>

  3、OK，准备工作就绪，可以实现单元测试的方法了。