Java高并发秒杀API之DAO层实现（一）

一 项目搭建和业务分析

1.前述

根据慕课网http://www.imooc.com/u/2145618/courses?sort=publish学习笔记

主要用到的技术: bootstrap,springMVC，spring，mybatis，mysql,redis,存储过程

一下为开发完成后的展示

2.前期项目准备

官网	地址
logback	https://logback.qos.ch/manual/configuration.html
spring	http://docs.spring.io/spring/docs
mybatis	http://www.mybatis.org/mybatis-3/zh/index.html

maven命令创建项目骨架

mvn archetype:create _DgroupId=org.seckill -DartifactId=seckill _DarchetypeArtifactId=maven-archetype-webapp

创建的web.xml是2.3的版本，默认不支持jstl表达式，可以去tomcat的examples下WEB-INF中web.xml中把3.1的头拷贝出来替换

<web-app xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" version="3.0"
metadata-complete="true">

（这个是3.0版也可以凑乎用）

补全目录结构



进入pom.xml,修改junit的版本为4.11 4使用注解，3使用编程

<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>

补全其他依赖

<!--  日志 slf4j  log4j logback  common-logging
slf4j 是接口
使用 slf4j+logback
-->
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.12</version>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-core</artifactId>
<version>1.1.1</version>
</dependency>
<dependency>
<!--实现slf4j 并整合 -->
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>1.1.1</version>
</dependency>
<!-- 数据库相关依赖 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.35</version>
</dependency>
<dependency>
<groupId>c3p0</groupId>
<artifactId>c3p0</artifactId>
<version>0.9.1.2</version>
</dependency>
<!--2.dao框架:MyBatis依赖-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.3.0</version>
</dependency>
<!--mybatis自身实现的spring整合依赖-->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>1.2.3</version>
</dependency>
<dependency>
<groupId>taglibs</groupId>
<artifactId>standard</artifactId>
<version>1.1.2</version>
</dependency>
<dependency>
<groupId>jstl</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
<dependency>
<groupId>com.fasterxml.jackson.core</groupId>
<artifactId>jackson-databind</artifactId>
<version>2.5.4</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>javax.servlet-api</artifactId>
<version>3.1.0</version>
</dependency>

<!--4:spring依赖-->
<!--1)spring核心依赖-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>4.1.7.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>4.1.7.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>4.1.7.RELEASE</version>
</dependency>
<!--2)spring dao层依赖-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-jdbc</artifactId>
<version>4.1.7.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-tx</artifactId>
<version>4.1.7.RELEASE</version>
</dependency>
<!--3)springweb相关依赖-->

113be
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>4.1.7.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>4.1.7.RELEASE</version>
</dependency>
<!--4)spring test相关依赖-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>4.1.7.RELEASE</version>
</dependency>
<!-- redis -->
<dependency>
<groupId>redis.clients</groupId>
<artifactId>jedis</artifactId>
<version>2.7.3</version>
</dependency>
<!-- protostuff序列化依赖 -->
<dependency>
<groupId>com.dyuproject.protostuff</groupId>
<artifactId>protostuff-core</artifactId>
<version>1.0.8</version>
</dependency>
<dependency>
<groupId>com.dyuproject.protostuff</groupId>
<artifactId>protostuff-runtime</artifactId>
<version>1.0.8</version>
</dependency>

<dependency>
<groupId>commons-collections</groupId>
<artifactId>commons-collections</artifactId>
<version>3.2</version>
</dependency>

3.秒杀业务分析

商家- - - -库存- - - -用户

商家添加库存，用户减库存，核心库存的处理

用户购买成功时需要减库存，记录购买明细，需要事务一致，完成数据落地

难点 :多用户竞争

流程

1.开启事务

2.update更新库存

3.insert 插入购买明细

4.commit

锁竞争在 第二步，update更新库存

其他用户在减库存时，只能在commit之后减库存

4.表设计

create database seckill;
--使用数据库
use seckill;

--创建秒杀数据表
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';

AUTO_INCREMENT 从1000开始

注意：

timestamp有两个属性，分别是CURRENT_TIMESTAMP 和ON UPDATE CURRENT_TIMESTAMP两种，设置为timestamp时会自动分配这两个属性中的一个属性。

1. CURRENT_TIMESTAMP

当要向数据库执行insert操作时，如果有个timestamp字段属性设为 CURRENT_TIMESTAMP，则无论这个字段有没有set值都插入当前系统时间

2. ON UPDATE CURRENT_TIMESTAMP

当执行update操作是，并且字段有ON UPDATE CURRENT_TIMESTAMP属性。则字段无论值有没有变化，它的值也会跟着更新为当前UPDATE操作时的时间。

-- 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'

5.实体编写

在entity下写对应的实体Seckill，SuccessKilled

在dao层写对应接口SeckillDao，SuccessKilledDao

SeckillDao

package org.seckill.dao;

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

import org.apache.ibatis.annotations.Param;
import org.seckill.entity.Seckill;

public interface SeckillDao {
//减库存
int reduceNumber(@Param("seckillId")long seckillId,@Param("killTime")Date killTime);
//根据id查询秒杀对象
Seckill queryById(long seckillId);
//根据偏移量查询秒杀商品列表
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);
}

SuccessKilledDao

package org.seckill.dao;

import org.apache.ibatis.annotations.Param;
import org.seckill.entity.SuccessKilled;

public interface SuccessKilledDao {
//插入购买明细，可过滤重复
int insertSuccessKilled(@Param("seckillId")long seckilled,@Param("userPhone")long userPhone);
//根据id查询successkiled 并携带秒杀产品对象实体
SuccessKilled queryByIdWithSeckill(@Param("seckillId")long seckilled,@Param("userPhone")long userPhone);
}

mybatis 数据库和java对象做映射

有两种实现一种写在xml中，另一种写在注解中

实现接口 一种是mapper实现，一种是api实现

在resource下写mybatis的配置文件mybatis-config.xml

在官网的入门中找配置和mapper的配置

<?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>
<!-- p配置全局属性 -->
<settings>
<!-- 使用jdbc的getGeneratedKeys  获取数据库自增主键值 -->
<setting name="useGeneratedKeys" value="true"/>
<!-- 使用列别名 替换列名 -->
<setting name="useColumnLabel" value="true"/>
<!--开启驼峰命名转换  -->
<setting name="mapUnderscoreToCamelCase" value="true"/>
</settings>
</configuration>

mapper配置

<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.seckill.dao.SeckillDao">
<!--目的:为dao接口方法提供sql语句配置
即针对dao接口中的方法编写我们的sql语句-->

</mapper>

SeckillDao.xml

<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.seckill.dao.SeckillDao">
<!--目的:为dao接口方法提供sql语句配置
即针对dao接口中的方法编写我们的sql语句-->

<update id="reduceNumber">
UPDATE seckill
SET number = number-1
WHERE seckill_id=#{seckillId}
AND start_time <![CDATA[ <= ]]> #{killTime}
AND end_time >= #{killTime}
AND number > 0;
</update>

<select id="queryById" resultType="Seckill" parameterType="long">
SELECT *
FROM seckill
WHERE seckill_id=#{0}
</select>

<select id="queryAll" resultType="Seckill" >
SELECT *
FROM seckill
ORDER BY create_time DESC
limit #{offset},#{limit}
</select>

<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>

<= 用

<![CDATA[ <= ]]>

替换，xml验证不报错

SuccessKilledDao.xml

<!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="org.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>

left join(左联接) 返回包括左表中的所有记录和右表中联结字段相等的记录

right join(右联接) 返回包括右表中的所有记录和左表中联结字段相等的记录

inner join(等值连接) 只返回两个表中联结字段相等的行

6.mybatis整合spring

使用spring 更少的类扫描和mapper扫描，自动实现dao接口，自动注入spring容器中

coding

resource下创建spring目录

创建spring-dao.xml

7.单元测试

SeckillDaoTest

package org.seckill.dao;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.seckill.entity.Seckill;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

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

/**
*
* 配置spring和junit整合，这样junit在启动时就会加载spring容器
*/
@RunWith(SpringJUnit4ClassRunner.class)
//告诉junit spring的配置文件
@ContextConfiguration({"classpath:spring/spring-dao.xml"})
public class SeckillDaoTest {

//注入Dao实现类依赖
@Autowired
private SeckillDao seckillDao;

@Test
public void queryById() throws Exception {
try{
long seckillId=1000;
Seckill seckill=seckillDao.queryById(seckillId);
System.out.println("alaala");
System.out.println(seckill.getName());
System.out.println(seckill);
}catch(Exception e){
e.printStackTrace();
}
}

@Test
public void queryAll() throws Exception {
try{
List<Seckill> seckills=seckillDao.queryAll(0,100);
for (Seckill seckill : seckills)
{
System.out.println(seckill);
}
}catch(Exception e){
e.printStackTrace();
}
}

@Test
public void reduceNumber() throws Exception {
try{
long seckillId=1000;
Date date=new Date();
int updateCount=seckillDao.reduceNumber(seckillId,date);
System.out.println(updateCount);
}catch(Exception e){
e.printStackTrace();
}
}

}

SuccessKilledDaoTest

package org.seckill.dao;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.seckill.entity.SuccessKilled;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import javax.annotation.Resource;

import static org.junit.Assert.*;

/**
*
*/
@RunWith(SpringJUnit4ClassRunner.class)
//告诉junit spring的配置文件
@ContextConfiguration({"classpath:spring/spring-dao.xml"})
public class SuccessKilledDaoTest {

@Resource
private SuccessKilledDao successKilledDao;

@Test
public void testInsertSuccessKilled() throws Exception {

long seckillId=1000L;
long userPhone=13476191877L;
int insertCount=successKilledDao.insertSuccessKilled(seckillId,userPhone);
System.out.println("insertCount="+insertCount);
}

@Test
public void TestqueryByIdWithSeckill() throws Exception {
try{
long seckillId=1000L;
long userPhone=13476191877L;
SuccessKilled successKilled=successKilledDao.queryByIdWithSeckill(seckillId,userPhone);
System.out.println(successKilled);
System.out.println(successKilled.getSeckill());
}catch (Exception e){
e.printStackTrace();
}

}

}