最近实在太忙,之前写的《rxjava系列文章》告一段落,还有两篇会在一月中旬补上,感谢大家。这篇文章讲述mybatis搭建DAO层,另外这系列文章是我看完《Java高并发秒杀系列》的课程整理的,所以文章采用的例子也来源于这系列课程。
一.环境/工具
1.开发工具idea
2.数据库MySQL
3.javaweb容器 tomcat
4.构建项目工具maven
关于这几个工具下载安装,环境的搭建就不介绍,自行百度。
二.采用maven 构建项目
采用命令构架,当然也可以采用ide 直接构建。
构建命令:
mvn archetype:generate -DgroupId=org.forezp -DartifactId=minnkill -DarchetypeArtifactId=maven-archetype-webapp
低版本maven需要将generate 改为create.
三.补全SSM框架相关依赖
下面是SSM框架所需的所有框架
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>org.seckill</groupId> <artifactId>seckill</artifactId> <packaging>war</packaging> <version>1.0.0</version> <name>seckill Maven Webapp</name> <url>http://maven.apache.org</url> <dependencies> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>4.11</version> <scope>test</scope> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-api</artifactId> <version>1.5.6</version> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-core</artifactId> <version>1.1.1</version> </dependency> <dependency> <groupId>ch.qos.logback</groupId> <artifactId>logback-classic</artifactId> <version>1.1.1</version> </dependency> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.35</version> <scope>runtime</scope> </dependency> <dependency> <groupId>c3p0</groupId> <artifactId>c3p0</artifactId> <version>0.9.1.2</version> </dependency> <dependency> <groupId>commons-dbcp</groupId> <artifactId>commons-dbcp</artifactId> <version>1.4</version> </dependency> <dependency> <groupId>org.mybatis</groupId> <artifactId>mybatis</artifactId> <version>3.3.0</version> </dependency> <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> <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-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> <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> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-test</artifactId> <version>4.1.7.RELEASE</version> </dependency> <dependency> <groupId>commons-collections</groupId> <artifactId>commons-collections</artifactId> <version>3.2</version> </dependency> </dependencies> <build> <finalName>seckill</finalName> </build></project>
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四.建数据库
仿java高并发秒杀系列》的视频,建了两张表,一张上库存表,一张上秒杀表,我直接贴sql语句了,比较简单。
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 DEFAULT "2016-05-07 13:28:00",`end_time` timestamp NOT NULL DEFAULT "2016-05-07 13:28:00",`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';insert into seckill(name,number,start_time,end_time)VALUES ('1000元秒杀iphone6',100,'2015-11-01 00:00:00','2015-11-02 00:00:00'), ('500元秒杀ipad2',200,'2015-11-01 00:00:00','2015-11-02 00:00:00'), ('300元秒杀小米4',300,'2015-11-01 00:00:00','2015-11-02 00:00:00'), ('200元秒杀红米note',400,'2015-11-01 00:00:00','2015-11-02 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 0 COMMENT '状态标示:-1:无效 0:成功 1:已付款',`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='秒杀明细表';
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五.DAO层实体编写和接口编写
1.创建org.forezp.entity包,根据数据库字段,编写实体。
下面是Seckill库存实体:
public class Seckill { private long seckillId; private String name; private int number; private Date startTime; private Date endTime; private Date createTime; }
- 创建org.forezp.dao包
编写Seckill接口
public interface SeckillDao { int reduceNumber(@Param("seckillId")long seckillId,@Param("killTime")Date killTime); Seckill queryById(long seckillId); List<Seckill> queryAll(@Param("offset")int offset,@Param("limit")int limit);
采用mapper实现接口
在resources目录下创建maaper文件夹,所有的接口实现类放在这里 ,另外项目采用xml的方式实现接口。采用这种方式的好处有很多,比如可以采用包扫描,更少的配置,所有的sql语句都放在这里,有利于统一规范,代码的可维护性和可读性也大大提高。
<?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.forezp.dao.SeckillDao"> <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 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 desc limit #{offset},#{limit} </select></mapper>
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六. mybatis的配置
创建mybatis-config.xml 全局配置:
<?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"> <settings> <setting name="useGeneratedKeys" value="true"/> <setting name="useColumnLabel" value="true"/> <setting name="mapUnderscoreToCamelCase" value="true"/> </settings></configuration>
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创建jdbc.properties文件
数据库配置文件和连接数据库驱动。
driver=com.mysql.jdbc.Driverurl=jdbc:mysql://localhost:3306/seckill?useUnicode=true&characterEncoding=utf8username=rootpassword=123
七.mybatis和spring 整合
直接贴配置文件,文件已经写好了注释。
<?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"> <context:property-placeholder location="classpath:jdbc.properties"/> <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource"> <property name="driverClassName" value="com.mysql.jdbc.Driver"/> <property name="url" value="jdbc:mysql://127.0.0.1:3306/seckill"/> <property name="username" value="root"/> <property name="password" value="123"/> </bean> <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.forezp.entity"/> <property name="mapperLocations" value="classpath:mapper/*.xml"/> </bean> <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/> <property name="basePackage" value="org.forezp.dao"/> </bean></beans>
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就这样mybatis和spring就整合好了,spring 提供了的ioc容器,为我们管理bean,我们不需要管理bean的生命周期.
八.单元测试
采用junit单元测试,spring 对junit做了很好的支持。只需要配置注解久可以了,
/** * 配置spring和junit整合,junit启动时加载springIOC容器 */@RunWith(SpringJUnit4ClassRunner.class)@ContextConfiguration(locations = {"classpath*:spring/spring-dao.xml"})public class SeckillDaoTest { @Test public void reduceNumber() throws Exception { Date killTIme=new Date(); int updateCount =seckillDao.reduceNumber(1000L,killTIme); System.out.println(updateCount); } @Resource private SeckillDao seckillDao; @Test public void queryById() throws Exception { long id=1001; Seckill seckill=seckillDao.queryById(id); System.out.println(seckill.getName()); System.out.println(seckill); /** 500元秒杀ipad2*/ /** Seckill{seckillId=1001, name='500元秒杀ipad2',number=200, startTime=Sun Nov 01 00:00:00 CST 2015, endTime=Mon Nov 02 00:00:00 CST 2015, createTime=Sun Nov 27 10:44:30 CST 2016}*/ } @Test public void queryAll() throws Exception { List<Seckill> seckills=seckillDao.queryAll(0,100); for(Seckill seckill:seckills){ System.out.println(seckill); } }}
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到此为止,mybatis实现数据库的连接,和dao层代码的编写以及mybatis 和spring的整合 。我觉得学习路上虽然很孤单,但如果有一个分享的心态和持续学习的动力,生活也算是充实的,自己成长了,技术也提高了,回报也高了,生活品质也随之提高。所以无论做什么,自己快乐,并且能提高自己的快乐,且以此为目的就够了,祝自己好运。
源码下载