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SpringMVC集成Mybatis高并发秒杀系统(1)-DAO

我是小小懒 2022-11-22 阅读 79
springxmljava虚拟化云计算


1.文章为转载翻译​​高并发秒杀系统实例​​​,有侵权请及时通知.
一.根据业务需求选取jar包.
DAO层采用Mybatis，交由SpringIOC容器管理，数据源c3p0管理,mysql数据库所以初步选择的包种有:
Spring4.1.7,
Mybatis
mybatis-spring整合包
c3p0及其依赖
mysql驱动包

主要掌握:

1.如何基于只写接口和配置完成DAO层，即不用写DAO层的实例类？

2.如何处理mybatis和spring的整合配置

3.常见的问题解决方案

一.结果

SpringMVC集成Mybatis高并发秒杀系统(1)-DAO_xml


SeckillDao

package org.seckill.dao;

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

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

public interface SeckillDao {
    /**
     * 减少库存
     * @param seckillId
     * @param killTime
     * @return >1则返回更新的行数
     */
    int reduceNumber(@Param("seckillId")long seckillId,@Param("killTime")Date killTime);    
    Seckill queryById(long seckillId); 
    /**
     * 分页获取全部
     * @param offset 起始位置
     * @param limit  单页条数
     * @return
     */
    List<Seckill> queryAll(@Param("offset")int offset,@Param("limit")int limit);   
}

SuccessKilledDao.java

package org.seckill.dao;

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

public interface SuccessKilledDao {
 int insertSucessKilled(@Param("seckillId")long seckillId,@Param("userPhone")long userPhone);

 /**
  * 通过id获取成功秒杀单信息对象，和取得秒杀对象
  * @param seckillId
  * @return
  */
 SuccessKilled queryByIdwithSeckill(long seckillId);
}

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="org.seckill.dao.SeckillDao">
    <update id="reduceNumber">
        <![CDATA[
            update 
              seckill 
            set 
              number = number-1 
            where seckill_id = #{seckillId} 
            and start_time <= #{killTime} 
            and end_time >= #{killTime}
            and number > 0
        ]]>
    </update>


    <select id="queryById" resultType="Seckill" parameterType="long">
     <![CDATA[
        select seckill_id,name,number,start_time,end_time,create_time 
        from seckill
        where seckill_id = #{seckillId}

     ]]>
    </select>

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

SuccessKilledDao.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="org.seckill.dao.SuccessKilledDao">
    <insert id="insertSucessKilled">
        <![CDATA[
            insert ignore into success_killed(seckill_id,user_phone)
            values(#[seckillId],#{userPhone})
        ]]>
    </insert>

    <select id="queryByIdwithSeckill" resultType="SuccessKilled">
        <![CDATA[
            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}
        ]]>
    </select>
</mapper>

Seckill.java

package org.seckill.entity;

import java.util.Date;

public class Seckill {
    private long seckillId;

    private String name;

    private int number;

    private Date startTime;

    private Date endTime;

    private Date creatTime;
    //省略get,set方法和toString
}

SuccessKilled.java

package org.seckill.entity;

import java.util.Date;

public class SuccessKilled {
    private long seckillId;

    private long userPhone;

    private short state;

    private Date createTime;

    //拓展多对一
    private Seckill seckill;
    //getter,setter,toString...
}

SeckillDaoTest.java

package org.seckill.test;

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

import javax.annotation.Resource;

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

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:spring-dao.xml")
public class SeckillDaoTest {
//  @Resource 测试注入成功
//  private  SqlSessionFactoryBean ssfb;

//  @Resource  注入成功
//  private  ComboPooledDataSource cpd;

//  @Resource  注入成功
//  private  MapperScannerConfigurer ddd;

//  @Resource   注入成功
//  private  MapperScannerConfigurer ddd;

    @Resource
    private SeckillDao seckillDao;
    @Test
    public void testReduceNumber() {
        try{
            int i = seckillDao.reduceNumber(1000l, new Date());
            System.out.println(i);
            }catch (Exception e) {
                System.out.println("出问题了");
                e.printStackTrace();
            }
    }

    @Test
    public void testQueryById() {
        try{
            Seckill seckill = seckillDao.queryById(1000);
            System.out.println(seckill);
            }catch (Exception e) {
                System.out.println("出问题了");
                e.printStackTrace();
            }
    }

    @Test
    public void testQueryAll() {
        try{
            List<Seckill> seckillList = seckillDao.queryAll(1, 10);
            System.out.println(seckillList.size());
            }catch (Exception e) {
                System.out.println("出问题了");
                e.printStackTrace();
            }
    }
}

jdbc.properties

driver=com.mysql.jdbc.Driver
url=jdbc:mysql://127.0.0.1:3306/seckill?useUnicode=true&characterEncoding=utf8
uname=root
password=123

log4j.properties

# Configure logging for testing: optionally with log file
log4j.rootLogger=WARN, stdout
# log4j.rootLogger=WARN, stdout, logfile

log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%d %p [%c] - %m%n

log4j.appender.logfile=org.apache.log4j.FileAppender
log4j.appender.logfile.File=target/spring.log
log4j.appender.logfile.layout=org.apache.log4j.PatternLayout
log4j.appender.logfile.layout.ConversionPattern=%d %p [%c] - %m%n

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>
    <!-- 配置全局属性 -->
    <settings>
        <!-- 使用generatedKeys去获取自增主键值 -->
        <setting name="useGeneratedKeys" value="true"></setting>
        <!-- 使用列别名替代列名 -->
        <setting name="useColumnLabel" value="true"></setting>
        <!-- 开启驼峰命名转换 -->
        <setting name="mapUnderscoreToCamelCase" value="true"></setting>
    </settings>
  </configuration>

spring-dao.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:context="http://www.springframework.org/schema/context"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
    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.配置数据库信息 -->
    <context:property-placeholder location="classpath:jdbc.properties"/>

    <!-- 2.配置数据池 -->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="driverClass" value="${driver}" />
        <property name="jdbcUrl" value="${url}" />
        <property name="user" value="${uname}" />
        <property name="password" value="${password}" />

        <!-- C3P0私有属性 -->
        <property name="maxPoolSize" value="30" />
        <property name="minPoolSize" value="10" />
        <property name="autoCommitOnClose" value="false" />
        <property name="checkoutTimeout" value="5000" />
        <!-- 获取连接失败重试次数 -->
        <property name="acquireRetryAttempts" value="9" />
    </bean>

<!-- 3.配置工厂 -->
    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
        <property name="dataSource" ref="dataSource" />
        <property name="configLocation" value="classpath:mybatis-config.xml" />
        <property name="typeAliasesPackage" value="org.seckill.entity" />
        <property name="mapperLocations" value="classpath:org/seckill/dao/mapper/*Dao.xml" />
    </bean>

  <!-- 4：配置扫描Dao接口的包，动态实现Dao接口，注入到Spring容器中 -->
    <bean id="ddd" class="org.mybatis.spring.mapper.MapperScannerConfigurer">
        <!--这里是今天要说的重点-->
        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"></property>
        <!-- 给出需要扫描的Dao接口包 -->
        <property name="basePackage" value="org.seckill.dao"></property>
    </bean>
</beans>

数据库mysql

/*1.创建数据库*/
CREATE DATABASE seckill;
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'秒杀开启时间',
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),
index 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,'2017-11-01 00:00:00','2017-11-02 00:00:00');

insert into seckill(name,number,start_time,end_time)
values('500元秒杀ipad2',200,'2017-11-01 00:00:00','2017-11-02 00:00:00');

insert into seckill(name,number,start_time,end_time)
values('300元秒杀小米4',300,'2017-11-01 00:00:00','2017-11-02 00:00:00');

insert into seckill(name,number,start_time,end_time)
values('200元秒杀红米note',400,'2017-11-01 00:00:00','2017-11-02 00:00:00');


/*  */
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'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';

二.解析
1.@Param(“”) 形参标识怎么使用？
当在mapper里的输入参数有两个时，就必须在接口的形参里增加Param注解，不然无法在执行sql语句时辨识，虽然接口形参写的十分明确，但是java对形参的保存基本是没有的，offset和limit相当于arg1,arg2,在select语句#取值的时候会分辨不清，必须用Param注解标识.

2.offset和limit有什么使用意义呢?
准备一张有十条数据以上的的表，执行语句select * from table limit 8,10
表达的含义是，从第八条数据开始显示数据，一直显示十条，即分页功能offset=8,limit=10

3.

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}

可以发现，对sickill对象的赋值也是把sickill对象的内属性一个一个的赋上去的，先是经过驼峰转换，把下划线替换成后字母大写，再根据属性映射装配给sickill对象,之所以加隐号是为了避免解析器误解，驼峰转换被注解说明在mybatis-config.xml

7.执行过程中遇到过的问题与解决方案

1.各种ClassNotFound，从提示里选中找不到的类，百度一哈属于什么jar包，补一哈子就行了，比如放入了c3p0包之后，报mchange什么什么找不到，就知道了c3p0还依赖一个mchange-commons-java-xxx.jar,
2.No appenders could be found for logger,没配置log4.properties时就报出这样的错.
3.context:property-placeholder标签未声明异常,xml文件总有红叉
头上面增加:
​​​http://www.springframework.org/schema/context​​​ ​​http://www.springframework.org/schema/context/spring-context.xsd​​​
4.最重要的最重要的找了很久的错误的
jdbc.properties里的用户名属性千万不要写username,这样在取${username}的时候怕是取的是windows环境变量下的username了，还有数据源ComboPooledDataSource的属性是user而不是username，这一点一定要跟其他数据源分清。

5.bug修改

SpringMVC集成Mybatis高并发秒杀系统(1)-DAO_spring_02


内嵌驼峰转换好像总是会报错，当SuccessKilled里的seckill对象也需要驼峰内置转换的时候会报错，修改一下:

<select id="queryByIdwithSeckill" resultMap="getSuccessKilled">
        <![CDATA[
        select 
              sk.seckill_id,
              sk.user_phone,
              sk.create_time,
              sk.state,
              s.seckill_id,
              s.name,
              s.number,
              s.start_time,
              s.end_time,
              s.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>
    <resultMap type="org.seckill.entity.SuccessKilled" id="getSuccessKilled">
        <id property="seckillId" column="sk.seckill_id"/>
        <result property="userPhone" column="sk.user_phone"/>
        <result property="state" column="sk.state"/>
        <result property="createTime" column="sk.create_time"/>
        <association property="seckill" javaType="org.seckill.entity.Seckill">
            <id property="seckillId" column="s.seckill_id"/>
            <result property="name" column="s.name"/>
            <result property="number" column="s.number"/>
            <result property="startTime" column="s.start_timee"/>
            <result property="endTime" column="s.end_time"/>
            <result property="creatTime" column="s.create_time"/>
        </association>  
    </resultMap>

搞定


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