【JAVA高併發秒殺API之DAO層】課程筆記

時間 2019-11-21

標籤 java 併發秒殺 api dao 課程筆記欄目 Java 简体版

原文原文鏈接

最近在慕課網上學習了【Java高併發秒殺API】系列課程，在此整理課程內容！html

課程收穫：一、學習瞭如何經過maven建立web項目，pom.xml 文件依賴管理。java

二、學習如何整合spring+mybatismysql

三、學習了相關配置文件的書寫。web

1、使用maven建立web項目

建立過程省略。。。spring

建立完畢，目錄結構以下：sql

相關說明：src/main/java下面放 java代碼數據庫

src/main/resources下面放配置文件等。apache

src/test/是相關單元測試的文件。api

能夠新建一個src/test/sql/ 下面存放建立數據庫和表格的SQL源碼mybatis

首先須要修改web.xml中的servlet版本：

<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">

</web-app>

建立完畢以後須要填寫pom.xml文件，經常使用的依賴包已經配置在pom.xml之中，具體以下：

<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>0.0.1-SNAPSHOT</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>

<!-- 1:日誌 java日誌：slf4j, log4j, logback, common-logging

slf4j 是規範/接口

日誌實現：log4j, logback, common-logging

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>1.1.2</version>

</dependency>

<dependency>

<groupId>ch.qos.logback</groupId>

<artifactId>logback-classic</artifactId>

<version>1.1.2</version>

</dependency>

<dependency>

<groupId>mysql</groupId>

<artifactId>mysql-connector-java</artifactId>

<version>5.1.38</version>

<scope>runtime</scope>

</dependency>

<dependency>

<groupId>c3p0</groupId>

<artifactId>c3p0</artifactId>

<version>0.9.1.2</version>

</dependency>

<dependency>

<groupId>org.mybatis</groupId>

<artifactId>mybatis</artifactId>

<version>3.2.8</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>2.7.4</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>4.2.6.RELEASE</version>

</dependency>

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-beans</artifactId>

<version>4.2.6.RELEASE</version>

</dependency>

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-context</artifactId>

<version>4.2.6.RELEASE</version>

</dependency>

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-jdbc</artifactId>

<version>4.2.6.RELEASE</version>

</dependency>

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-tx</artifactId>

<version>4.2.6.RELEASE</version>

</dependency>

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-web</artifactId>

<version>4.2.6.RELEASE</version>

</dependency>

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-webmvc</artifactId>

<version>4.2.6.RELEASE</version>

</dependency>

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-test</artifactId>

<version>4.2.6.RELEASE</version>

</dependency>

</dependencies>

</project>

至此，一個整合spring+mybatis 的 web項目基本搭建完畢！！

2、鏈接數據庫相關配置

以下圖，在src/main/resources 下建立jdbc.properties 文件（驅動、url、用戶名、密碼等設置）

在src/main/resources 下建立mybatis-config.xml 文件（配置mybatis全局屬性）

在src/main/resources下新建文件夾spring和mapper：spring下主要存spring相關配置文件，mapper主要存DAO的相關映射。

在src/main/resources/spring/下建立文件spring-dao.xml 文件（配置鏈接數據庫，整合mybatis配置）

jdbc.properties文件內容：（注意變量名必須這樣寫，不能自定義）

jdbc.driverClass=com.mysql.jdbc.Driver

jdbc.jdbcUrl=jdbc:mysql://localhost:3306/seckill?useUnicode=true&characterEncoding=utf8

jdbc.user=tao

jdbc.password=password

mybatis-config.xml文件內容：

<?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>

<setting name="useGeneratedKeys" value="true"/>

<setting name="useColumnLabel" value="true"/>

<setting name="mapUnderscoreToCamelCase" value="true"/>

</settings>

</configuration>

spring-dao.xml文件內容：（注意：classpath指代的是src/main/java和src/main/resources）

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/2002/xmlspec/dtd/2.10/xmlspec.dtd">

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:p="http://www.springframework.org/schema/p"

xmlns:tx="http://www.springframework.org/schema/tx"

xmlns:aop="http://www.springframework.org/schema/aop"

xmlns:context="http://www.springframework.org/schema/context"

xsi:schemaLocation="http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans-4.2.xsd

http://www.springframework.org/schema/tx

http://www.springframework.org/schema/tx/spring-tx.xsd

http://www.springframework.org/schema/aop

http://www.springframework.org/schema/aop/spring-aop.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="com.mchange.v2.c3p0.ComboPooledDataSource" destroy-method="close">

<property name="driverClass" value="${jdbc.driverClass}"></property>

<property name="jdbcUrl" value="${jdbc.jdbcUrl}"></property>

<property name="user" value="${jdbc.user}"></property>

<property name="password" value="${jdbc.password}"></property>

<property name="minPoolSize" value="10"></property>

<property name="maxPoolSize" value="30"></property>

<property name="autoCommitOnClose" value="false"></property>

<property name="checkoutTimeout" value="1000"></property>

<property name="acquireRetryAttempts" value="2" />

</bean>

<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">

<property name="dataSource" ref="dataSource" />

<property name="configLocation" value="classpath:mybatis-config.xml"></property>

<property name="typeAliasesPackage" value="org.seckill.entity"></property>

<property name="mapperLocations" value="classpath:mapper/*.xml"></property>

</bean>

<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">

<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"></property>

<property name="basePackage" value="org.seckill.dao" />

</bean>

</beans>

（注意：代碼中高亮部分相關文件的位置能夠根據具體項目進行填寫）

至此，基本配置完畢！

3、編寫DAO以及DAO映射

在編寫DAO以前，須要建立數據庫表格（建立過程省略。。。）

相關SQL語句：schema.sql文件

-- 數據庫初始化腳本

-- 建立數據庫

CREATE DATABASE seckill;

-- 使用數據庫

use seckill;

-- 建立秒殺庫存表

CREATE TABLE seckill(

seckill_id bigint NOT NULL AUTO_INCREMENT COMMENT '商品庫存id',

name varchar(120) NOT NULL COMMENT '商品名稱',

number int NOT NULL COMMENT '庫存數量',

create_time timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '建立時間',

start_time DATETIME NOT NULL COMMENT '秒殺開啓時間',

end_time DATETIME NOT NULL COMMENT '秒殺結束時間',

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='秒殺庫存表';

-- 初始化數據

insert into

seckill(name, number, start_time, end_time)

values

('1000元秒殺iphon6', 100, '2015-11-01 00:00:00', '2015-11-02 00:00:00'),

('500元秒殺ipadmini2', 200, '2016-06-24 00:00:00', '2016-06-25 00:00:00'),

('300元秒殺小米手機', 300, '2016-06-26 00:00:00', '2015-06-27 00:00:00'),

('1999元秒殺ipadAir', 400, '2016-06-29 00:00:00', '2016-06-30 00:00:00'),

('5999元秒殺macbook', 500, '2016-06-29 00:00:00', '2016-06-30 00:00:00');

-- 秒殺成功明細表

-- 用戶登陸相關的信息

CREATE TABLE success_killed(

seckill_id bigint NOT NULL COMMENT '商品庫存id',

user_phone bigint NOT NULL COMMENT '用戶手機號',

state tinyint NOT NULL DEFAULT -1 COMMENT '狀態標識:-1:無效 0:成功 1:已付款',

create_time timestamp NOT NULL COMMENT '建立時間',

PRIMARY KEY (seckill_id, user_phone),

KEY idx_create_time(create_time)

)ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='秒殺成功明細表';

這裏有兩個表：seckill和success_killed表。

咱們須要兩個包：（1）org.seckill.entity包（保存實體）（2）org.seckill.dao包（保存與實體對應的DAO）

主要分三步：首先在src/main/java下的 org.seckill.entity 包建立實體

而後在src/main/java下的 org.seckill.dao 包建立對應的DAO

最後在src/main/resources下的mapper文件夾下建立對應的 XXXDao.xml 配置文件（SQL語句寫在配置文件中）

第一步：建立實體

Seckill. java文件：

package org.seckill.entity;

import java.util.Date;

public class Seckill {

private long seckillId;

private String name;

private int number;

private Date createTime;

private Date startTime;

private Date endTime;

public long getSeckillId() {

return seckillId;

}

public void setSeckillId(long seckillId) {

this.seckillId = seckillId;

}

public String getName() {

return name;

}

public void setName(String name) {

this.name = name;

}

public int getNumber() {

return number;

}

public void setNumber(int number) {

this.number = number;

}

public Date getCreateTime() {

return createTime;

}

public void setCreateTime(Date createTime) {

this.createTime = createTime;

}

public Date getStartTime() {

return startTime;

}

public void setStartTime(Date startTime) {

this.startTime = startTime;

}

public Date getEndTime() {

return endTime;

}

public void setEndTime(Date endTime) {

this.endTime = endTime;

}

//複寫toString()方法

@Override

public String toString() {

return "Seckill [seckillId=" + seckillId + ", name=" + name

+ ", number=" + number + ", createTime=" + createTime

+ ", startTime=" + startTime + ", endTime=" + endTime + "]";

}

}

SuccessKilled.java文件：

package org.seckill.entity;

import java.util.Date;

public class SuccessKilled {

private long seckillId;

private long userPhone;

private short state; //狀態標識:-1:無效 0:成功 1:已付款

private Date createTime;

//多對一：多個SuccessKilled對應一個Seckill

private Seckill seckill;

public long getSeckillId() {

return seckillId;

}

public void setSeckillId(long seckillId) {

this.seckillId = seckillId;

}

public long getUserPhone() {

return userPhone;

}

public void setUserPhone(long userPhone) {

this.userPhone = userPhone;

}

public short getState() {

return state;

}

public void setState(short state) {

this.state = state;

}

public Date getCreateTime() {

return createTime;

}

public void setCreateTime(Date createTime) {

this.createTime = createTime;

}

public Seckill getSeckill() {

return seckill;

}

public void setSeckill(Seckill seckill) {

this.seckill = seckill;

}

@Override

public String toString() {

return "SuccessKilled [seckillId=" + seckillId + ", userPhone="

+ userPhone + ", state=" + state + ", createTime=" + createTime

+ "]";

}

}

第二步：建立DAO

（注意：當DAO類中的方法有多個形參的時候，須要經過註解@Param("XXX")來告訴Mybatis須要的參數）

SeckillDao.java文件：

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 {

/**

* 減庫存

* @param seckillId

* @param killTime

* @return 若是返回>1，表示更新的記錄行數

*/

int reduceNumber(@Param("seckillId") long seckillId, @Param("killTime") Date killTime);

/**

* 根據ID查詢秒殺對象

* @param seckillId

* @return

*/

Seckill queryById(long seckillId);

/**

* 根據偏移量查詢秒殺商品列表

* @param offset

* @param limit

* @return

*/

List<Seckill> queryAll(@Param("offset") int offset, @Param("limit") int limit);

}

SuccessKilledDao.java文件：

package org.seckill.dao;

import org.apache.ibatis.annotations.Param;

import org.seckill.entity.SuccessKilled;

public interface SuccessKilledDao {

/**

* 插入購買明細，可過濾重複

* @param seckillId

* @param userPhone

* @return 返回插入結果的數量

*/

int insertSuccessKilled(@Param("seckillId") long seckillId, @Param("userPhone") long userPhone);

/**

* 根據id查詢SuccessKilled並攜帶秒殺商品對象

* @param seckillId

* @return

*/

SuccessKilled queryByIdWithSeckill(@Param("seckillId") long seckillId, @Param("userPhone") long userPhone);

}

第三步：DAO的配置文件

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="org.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 <![CDATA[ > ]]> 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" parameterType="int">

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="insertSuccessKilled" parameterType="long">

insert ignore into success_killed(seckill_id, user_phone, state)

values

(#{seckillId},#{userPhone}, 0)

</insert>

<select id="queryByIdWithSeckill" resultType="SuccessKilled" parameterType="long">

select

sk.seckill_id,

sk.user_phone,

sk.state,

sk.create_time,

s.seckill_id as "seckill.seckill_id",

s.name as "seckill.name",

s.number as "seckill.number",

s.start_time "seckill.start_time",

s.end_time as "seckill.end_time",

s.create_time as "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>

4、DAO的單元測試

單元測試的java文件保存在src/test/java下的相關包中。以下圖：

在單元測試類中，須要作一下預處理：

/**

*配置spring和junit整合，junit啓啓動時候加載spring IOC容器

*spring-test,junit

*/

@RunWith(SpringJUnit4ClassRunner.class)

//告訴junit spring配置文件的位置

@ContextConfiguration({"classpath:spring/spring-dao.xml"})

隨後在類中，使用註解@Resource 注入依賴

一、SeckillDaoTest.java文件

package org.seckill.dao;

import java.util.Date;

import java.util.List;

import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import javax.annotation.Resource;

import org.junit.Test;

import org.junit.runner.RunWith;

import org.seckill.entity.Seckill;

import org.springframework.test.context.ContextConfiguration;

/**

*配置spring和junit整合，junit啓啓動時候加載spring IOC容器

*spring-test,junit

*/

@RunWith(SpringJUnit4ClassRunner.class)

//告訴junit spring配置文件的位置

@ContextConfiguration({"classpath:spring/spring-dao.xml"})

public class SeckillDaoTest {

//注入Dao實現依賴

@Resource

private SeckillDao seckillDao;

@Test

public void testReduceNumber() throws Exception {

Date killTime = new Date();

int updateCount = seckillDao.reduceNumber(1000L, killTime);

System.out.println(updateCount);

}

@Test

public void testQueryById() throws Exception {

long id = 1000;

Seckill seckill = seckillDao.queryById(id);

System.out.println(seckill.getName());

System.out.println(seckill);

}

@Test

public void testQueryAll() throws Exception {

List<Seckill> seckills = seckillDao.queryAll(0, 100);

for(Seckill seckill : seckills) {

System.out.println(seckill);

}

}

}

二、SuccessKilledDaoTest.java

package org.seckill.dao;

import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import javax.annotation.Resource;

import org.junit.Test;

import org.junit.runner.RunWith;

import org.seckill.entity.SuccessKilled;

import org.springframework.test.context.ContextConfiguration;

/**

*配置spring和junit整合，junit啓啓動時候加載spring IOC容器

*spring-test,junit

*/

@RunWith(SpringJUnit4ClassRunner.class)

//告訴junit spring配置文件的位置

@ContextConfiguration({"classpath:spring/spring-dao.xml"})

public class SuccessKilledDaoTest {

@Resource

private SuccessKilledDao successKilledDao;

@Test

public void testInsertSuccessKilled() throws Exception {

long id = 1001L;

long phone = 18945681316L;

int insertCount = successKilledDao.insertSuccessKilled(id, phone);

System.out.println("insertCount= " + insertCount);

}

@Test

public void testQueryByIdWithSeckill() throws Exception {

long id = 1001L;

long phone = 18945681316L;

SuccessKilled successKilled = successKilledDao.queryByIdWithSeckill(id, phone);

System.out.println(successKilled);

System.out.println(successKilled.getSeckill());

}

}

以上即是整個DAO層的設計與配置！！

相關文章

相關標籤/搜索

筆記 Jvm-併發

併發編程筆記

Java 併發編程

Java併發編程

Java併發編程之美

Hibernate教程

每日一句

每一个你不满意的现在，都有一个你没有努力的曾经。

最新文章

本站公眾號

歡迎關注本站公眾號,獲取更多信息

相關文章

>>更多相關文章<<