官方文档：https://shardingsphere.apache.org/document/current/cn/overview/
学习视频：https://www.bilibili.com/video/BV1LK411s7RX?p=2&vd_source=fc7fa697b97f292319c5b0cde4755484
代码：https://gitee.com/wangzai6/sharding-jdbc.git

1.什么是ShardingSphere及相关核心概念

2.什么是分库分表

3.分库分表的方式

1.垂直分表

把操作数据库某张表，把这张表中一部分字段数据存到一张新表里面，再把这张表另一部分字段数据存到另外一张表里面

2.垂直分库

把单一数据库按照业务进行划分，专库专表

3.水平分库

解决单库数据量大的问题

4.水平分表

4.分库分表应用和问题

1.应用

1. 在数据库设计时候考虑垂直分库和垂直分表
2. 随着数据量增加，不要马上考虑做水平切分，收下考虑缓存处理，读写分离，使用索引等等方式，如果这些方式不能解决问题，再考虑做水平分库和水平分表
   

2.分库分表问题

1. 跨节点查询问题（分页，排序）
   
2. 多数据源管理问题

5.Sharding-JDBC简介

1.是轻量级的java框架，是增强的JDBC驱动

2.Sharding-jdbc不是做分库分表，主要做两个功能:数据分片和读写分离

6.案例

1.搭建环境

1.Springboot2.2.1+MybatisPlus+sharding-JDBC+Durid连接池

2.创建SpringBoot工程

3.引入依赖

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.2.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.hejiawang</groupId>
    <artifactId>sharding</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>sharding</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.20</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        <dependency>
            <groupId>org.apache.shardingsphere</groupId>
            <artifactId>sharding-jdbc-spring-boot-starter</artifactId>
            <version>4.0.0-RC1</version>
        </dependency>
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.0.5</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

4.水平分表案例

1.创建数据库course_db

2.在数据库创建两张表course_1和course_2

create table course_1(
    cid bigint(20) PRIMARY KEY ,
    cname varchar(50) not null ,
    user_id bigint(20) not null ,
    cstatus varchar(10) not null
)
create table course_2(
    cid bigint(20) PRIMARY KEY ,
    cname varchar(50) not null ,
    user_id bigint(20) not null ,
    cstatus varchar(10) not null
)

3.约定规则，如果添加课程id是偶数把数据添加到course_1，如果是奇数添加到course_2

Course

package com.hejiawang.sharding.entity;

import lombok.Data;

/**
 * @description:
 * @author: Mr.Wang
 * @create: 2022-07-13 16:34
 **/
@Data
public class Course {
    private Long cid;
    private String cname;
    private Long userId;
    private String cstatus;
}

CourseMapper

package com.hejiawang.sharding.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.hejiawang.sharding.entity.Course;
import org.springframework.stereotype.Repository;

/**
 * @description:
 * @author: Mr.Wang
 * @create: 2022-07-13 16:35
 **/
@Repository
public interface CourseMapper extends BaseMapper<Course> {
}

ShardingApplication

package com.hejiawang.sharding;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan("com.hejiawang.sharding.mapper")
public class ShardingApplication {

    public static void main(String[] args) {
        SpringApplication.run(ShardingApplication.class, args);
    }
}

application.properties

# shardingjdbc分片策略
#配置数据源，给数据源起名称
spring.shardingsphere.datasource.names=ds1

#一个实体类对应两张表，覆盖
spring.main.allow-bean-definition-overriding=true

# 配置数据源具体内容，包含连接池，驱动地址，用户名和密码
spring.shardingsphere.datasource.ds1.type=com.alibaba.druid.pool.DruidDataSource
#jdk1.8 com.mysql.cj.jdbc.Driver
#jdk1.8以下 om.mysql.jdbc.Driver
spring.shardingsphere.datasource.ds1.driver-class-name=com.mysql.cj.jdbc.Driver
spring.shardingsphere.datasource.ds1.url=jdbc:mysql://ip:端口/course_db?serverTimezone=Asia/Shanghai
spring.shardingsphere.datasource.ds1.username = xxx
spring.shardingsphere.datasource.ds1.password = xxx

#指定course表分布情况，配置表在哪个数据库里面，表名称都是什么 ds1.course_1 ds1.course_2
spring.shardingsphere.sharding.tables.course.actual-data-nodes=ds1.course_$->{1..2} 

# 指定course表里面主键cid生成策略 snowflake
spring.shardingsphere.sharding.tables.course.key-generator.column=cid
spring.shardingsphere.sharding.tables.course.key-generator.type=snowflake

# 指定分片策略 约定cid值偶数添加到course_1表，如果cid是奇数添加到course_2表
spring.shardingsphere.sharding.tables.course.table-strategy.inline.sharding-column=cid
spring.shardingsphere.sharding.tables.course.table-strategy.inline.algorithm-expression=course_$->{cid % 2 + 1}

#打开sql输出日志
spring.shardingsphere.props.sql.show=true

测试类 ShardingApplicationTests

package com.hejiawang.sharding;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.hejiawang.sharding.entity.Course;
import com.hejiawang.sharding.mapper.CourseMapper;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest
public class ShardingApplicationTests {
//  注入mapper
    @Autowired
    private CourseMapper courseeMapper;
//    添加课程
    @Test
    public void addCourse(){
        for (int i = 0 ; i <=10 ; i++){
            Course course = new Course();
            course.setCname("java");
            course.setUserId(100L);
            course.setCstatus("Normal"+i);
            courseeMapper.insert(course);
        }
    }

//    查询课程方法
    @Test
    public void findCourse(){
        QueryWrapper<Course> wrapper = new QueryWrapper();
//        wrapper.eq("cid",754034711998758913L);
        wrapper.eq("cid",754034712887951360L);
        Course course = courseeMapper.selectOne(wrapper);
        System.out.println(course);
    }
}

调用测试添加方法
cid通过雪花算法生成，如果为奇数则插入course_2，偶数则插入course_1
打印日志

5.水平分库案例

1.需求分析

2.创建数据库和表

create table course_1(
    cid bigint(20) PRIMARY KEY ,
    cname varchar(50) not null ,
    user_id bigint(20) not null ,
    cstatus varchar(10) not null
)
create table course_2(
    cid bigint(20) PRIMARY KEY ,
    cname varchar(50) not null ,
    user_id bigint(20) not null ,
    cstatus varchar(10) not null
)

3.在springboot配置数据库分片规则

application.properties

# shardingjdbc分片策略
#配置数据源，给数据源起名称,水平分库
spring.shardingsphere.datasource.names=ds1,ds2

#一个实体类对应两张表，覆盖
spring.main.allow-bean-definition-overriding=true

# 配置第一个数据源具体内容，包含连接池，驱动地址，用户名和密码
spring.shardingsphere.datasource.ds1.type=com.alibaba.druid.pool.DruidDataSource
#jdk1.8 com.mysql.cj.jdbc.Driver
#jdk1.8以下 om.mysql.jdbc.Driver
spring.shardingsphere.datasource.ds1.driver-class-name=com.mysql.cj.jdbc.Driver
spring.shardingsphere.datasource.ds1.url=jdbc:mysql://ip:端口/edu_db_1?serverTimezone=Asia/Shanghai
spring.shardingsphere.datasource.ds1.username = xxx
spring.shardingsphere.datasource.ds1.password = xxx

# 配置第二个数据源具体内容，包含连接池，驱动地址，用户名和密码
spring.shardingsphere.datasource.ds2.type=com.alibaba.druid.pool.DruidDataSource
#jdk1.8 com.mysql.cj.jdbc.Driver
#jdk1.8以下 om.mysql.jdbc.Driver
spring.shardingsphere.datasource.ds2.driver-class-name=com.mysql.cj.jdbc.Driver
spring.shardingsphere.datasource.ds2.url=jdbc:mysql://ip:端口/edu_db_2?serverTimezone=Asia/Shanghai
spring.shardingsphere.datasource.ds2.username = xxx
spring.shardingsphere.datasource.ds2.password = xxx

#指定数据库分布情况，数据库里面表分布情况
# ds1 ds2  course_1 course_2
spring.shardingsphere.sharding.tables.course.actual-data-nodes=ds$->{1..2}.course_$->{1..2}

# 指定course表里面主键cid生成策略 snowflake
spring.shardingsphere.sharding.tables.course.key-generator.column=cid
spring.shardingsphere.sharding.tables.course.key-generator.type=snowflake

# 指定表分片策略 约定cid值偶数添加到course_1表，如果cid是奇数添加到course_2表
spring.shardingsphere.sharding.tables.course.table-strategy.inline.sharding-column=cid
spring.shardingsphere.sharding.tables.course.table-strategy.inline.algorithm-expression=course_$->{cid % 2 + 1}

# 指定数据库分片策略 约定user_id是偶数添加ds1,是奇数添加ds2
# 数据库中所有表的规则
# spring.shardingsphere.sharding.default-database-strategy.inline.sharding-column=user_id
# spring.shardingsphere.sharding.default-database-strategy.inline.algorithm-expression=ds$->{userid % 2 + 1}
# 指定到具体表的库规则
spring.shardingsphere.sharding.tables.course.database-strategy.inline.sharding-column=user_id
spring.shardingsphere.sharding.tables.course.database-strategy.inline.algorithm-expression=ds$->{user_id % 2 + 1}


#打开sql输出日志
spring.shardingsphere.props.sql.show=true

4.编写测试方法

package com.hejiawang.sharding;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.hejiawang.sharding.entity.Course;
import com.hejiawang.sharding.mapper.CourseMapper;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest
public class ShardingApplicationTests {
//  注入mapper
    @Autowired
    private CourseMapper courseeMapper;
//    ===============测试水平分库=================
    @Test
    public void addCourseDb(){
            Course course = new Course();
            course.setCname("C++");
//            分库根据user_id
            course.setUserId(100L);
            course.setCstatus("Normal");
            courseeMapper.insert(course);
    }

    @Test
    public void findCourseDb(){
        QueryWrapper<Course> wrapper = new QueryWrapper();
//        wrapper.eq("cid",754034711998758913L);
        wrapper.eq("user_id",100L);
        wrapper.eq("cid",754375827029753857L);
        Course course = courseeMapper.selectOne(wrapper);
        System.out.println(course);
    }
//    ===============测试水平分表=================
//    添加课程
    @Test
    public void addCourse(){
        for (int i = 0 ; i <=10 ; i++){
            Course course = new Course();
            course.setCname("C语言");
            course.setUserId(100L);
            course.setCstatus("Normal"+i);
            courseeMapper.insert(course);
        }
    }

//    查询课程方法
    @Test
    public void findCourse(){
        QueryWrapper<Course> wrapper = new QueryWrapper();
//        wrapper.eq("cid",754034711998758913L);
        wrapper.eq("cid",754034712887951360L);
        Course course = courseeMapper.selectOne(wrapper);
        System.out.println(course);
    }
}

执行水平分库方法addCourseDb()，查看打印结果
数据库为ds1配置的数据源edu_db_1 下的course_2

查询方法，当只写userid的时候，打印2条sql course_1和course_2都查询了
查询方法，写userid和cid的时候，打印1条sql，直接查询到了

6.垂直分库案例

1.需求分析

2.创建数据库和表

create table t_user(
    user_id bigint(20) not null ,
    username varchar(100) not null,
    ustatus varchar(50) not null 
)

3.编写测试方法

注意 User实体类要映射到表名t_user，否则会报错

User

package com.hejiawang.sharding.entity;

import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

/**
 * @description:
 * @author: Mr.Wang
 * @create: 2022-07-14 16:33
 **/
@Data
@TableName(value = "t_user") //指定对应表
public class User {
    private Long userId;
    private String username;
    private String ustatus;
}

UserMapper

package com.hejiawang.sharding.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.hejiawang.sharding.entity.User;
import org.springframework.stereotype.Repository;

@Repository
public interface UserMapper extends BaseMapper<User> {
}

配置规则application.properties

# shardingjdbc分片策略
#配置数据源，给数据源起名称,水平分库
spring.shardingsphere.datasource.names=ds1,ds2,ds3

#一个实体类对应两张表，覆盖
spring.main.allow-bean-definition-overriding=true

# 配置第一个数据源具体内容，包含连接池，驱动地址，用户名和密码
spring.shardingsphere.datasource.ds1.type=com.alibaba.druid.pool.DruidDataSource
#jdk1.8 com.mysql.cj.jdbc.Driver
#jdk1.8以下 om.mysql.jdbc.Driver
spring.shardingsphere.datasource.ds1.driver-class-name=com.mysql.cj.jdbc.Driver
spring.shardingsphere.datasource.ds1.url=jdbc:mysql://ip:端口/edu_db_1?serverTimezone=Asia/Shanghai
spring.shardingsphere.datasource.ds1.username = xxx
spring.shardingsphere.datasource.ds1.password = xxx

# 配置第二个数据源具体内容，包含连接池，驱动地址，用户名和密码
spring.shardingsphere.datasource.ds2.type=com.alibaba.druid.pool.DruidDataSource
#jdk1.8 com.mysql.cj.jdbc.Driver
#jdk1.8以下 om.mysql.jdbc.Driver
spring.shardingsphere.datasource.ds2.driver-class-name=com.mysql.cj.jdbc.Driver
spring.shardingsphere.datasource.ds2.url=jdbc:mysql://ip:端口/edu_db_2?serverTimezone=Asia/Shanghai
spring.shardingsphere.datasource.ds2.username = xxx
spring.shardingsphere.datasource.ds2.password = xxx


# 配置第三个数据源具体内容，包含连接池，驱动地址，用户名和密码
spring.shardingsphere.datasource.ds3.type=com.alibaba.druid.pool.DruidDataSource
#jdk1.8 com.mysql.cj.jdbc.Driver
#jdk1.8以下 om.mysql.jdbc.Driver
spring.shardingsphere.datasource.ds3.driver-class-name=com.mysql.cj.jdbc.Driver
spring.shardingsphere.datasource.ds3.url=jdbc:mysql://ip:端口/user_db?serverTimezone=Asia/Shanghai
spring.shardingsphere.datasource.ds3.username = xxx
spring.shardingsphere.datasource.ds3.password = xxx

# 配置user_db数据库里面t_user 专库专表
spring.shardingsphere.sharding.tables.t_user.actual-data-nodes=ds$->{3}.t_user
spring.shardingsphere.sharding.tables.t_user.key-generator.column=user_id
spring.shardingsphere.sharding.tables.t_user.key-generator.type=snowflake
spring.shardingsphere.sharding.tables.t_user.table-strategy.inline.sharding-column=user_id
spring.shardingsphere.sharding.tables.t_user.table-strategy.inline.algorithm-expression=t_user

#指定数据库分布情况，数据库里面表分布情况
# ds1 ds2  course_1 course_2
spring.shardingsphere.sharding.tables.course.actual-data-nodes=ds$->{1..2}.course_$->{1..2}

# 指定course表里面主键cid生成策略 snowflake
spring.shardingsphere.sharding.tables.course.key-generator.column=cid
spring.shardingsphere.sharding.tables.course.key-generator.type=snowflake

# 指定表分片策略 约定cid值偶数添加到course_1表，如果cid是奇数添加到course_2表
spring.shardingsphere.sharding.tables.course.table-strategy.inline.sharding-column=cid
spring.shardingsphere.sharding.tables.course.table-strategy.inline.algorithm-expression=course_$->{cid % 2 + 1}

# 指定数据库分片策略 约定user_id是偶数添加ds1,是奇数添加ds2
# 数据库中所有表的规则
# spring.shardingsphere.sharding.default-database-strategy.inline.sharding-column=user_id
# spring.shardingsphere.sharding.default-database-strategy.inline.algorithm-expression=ds$->{userid % 2 + 1}
# 指定到具体表的库规则
spring.shardingsphere.sharding.tables.course.database-strategy.inline.sharding-column=user_id
spring.shardingsphere.sharding.tables.course.database-strategy.inline.algorithm-expression=ds$->{user_id % 2 + 1}


#打开sql输出日志
spring.shardingsphere.props.sql.show=true

测试类

package com.hejiawang.sharding;

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.hejiawang.sharding.entity.Course;
import com.hejiawang.sharding.entity.User;
import com.hejiawang.sharding.mapper.CourseMapper;
import com.hejiawang.sharding.mapper.UserMapper;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest
public class ShardingApplicationTests {
//  注入mapper
    @Autowired
    private CourseMapper courseeMapper;
    @Autowired
    private UserMapper userMapper;

//    ===============测试垂直分库=================
    @Test
    public void addUserDb(){
        User user = new User();
        user.setUsername("飞哥");
        user.setUstatus("牛逼");
        userMapper.insert(user);
    }
        @Test
        public void findUserDb(){
            QueryWrapper<User> wrapper = new QueryWrapper();
            wrapper.eq("user_id",754388854030467073L);
            User user = userMapper.selectOne(wrapper);
            System.out.println(user);
        }
//    ===============测试水平分库=================
    @Test
    public void addCourseDb(){
            Course course = new Course();
            course.setCname("C++");
//            分库根据user_id
            course.setUserId(100L);
            course.setCstatus("Normal");
            courseeMapper.insert(course);
    }

    @Test
    public void findCourseDb(){
        QueryWrapper<Course> wrapper = new QueryWrapper();
//        wrapper.eq("cid",754034711998758913L);
        wrapper.eq("user_id",100L);
        wrapper.eq("cid",754375827029753857L);
        Course course = courseeMapper.selectOne(wrapper);
        System.out.println(course);
    }
//    ===============测试水平分表=================
//    添加课程
    @Test
    public void addCourse(){
        for (int i = 0 ; i <=10 ; i++){
            Course course = new Course();
            course.setCname("C语言");
            course.setUserId(100L);
            course.setCstatus("Normal"+i);
            courseeMapper.insert(course);
        }
    }

//    查询课程方法
    @Test
    public void findCourse(){
        QueryWrapper<Course> wrapper = new QueryWrapper();
//        wrapper.eq("cid",754034711998758913L);
        wrapper.eq("cid",754034712887951360L);
        Course course = courseeMapper.selectOne(wrapper);
        System.out.println(course);
    }

}

运行addUserDb（）方法，走ds3数据源

运行findUserDb（）方法，走ds3数据源

7.Sharding-jdbc公共表

1.公共表

存储固定数据的表，表数据很少发生变化，查询时经常要关联的表
在每个数据库中创建相同结构公共表

2.创建数据库和表

在edu_db_1,edu_db_2,user_db中创建公共表

create table t_udict(
    dictid bigint(20) primary key ,
    ustatus varchar(100) not null ,
    uvalue varchar(100) not null
)

3.配置文件中配置规则

application.properties

# 配置公共表
spring.shardingsphere.sharding.broadcast-tables=t_udict
spring.shardingsphere.sharding.tables.t_udict.key-generator.type=snowflake
spring.shardingsphere.sharding.tables.t_udict.key-generator.column=dictid

4.编写测试规则

1.创建新实体类和mapper
Udict

package com.hejiawang.sharding.entity;

import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

/**
 * @description:
 * @author: Mr.Wang
 * @create: 2022-07-14 20:54
 **/
@Data
@TableName(value = "t_udict")
public class Udict {
    private Long dictid;
    private String ustatus;
    private String uvalue;
}

UdictMapper

package com.hejiawang.sharding.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.hejiawang.sharding.entity.Udict;
import org.springframework.stereotype.Repository;

@Repository
public interface UdictMapper extends BaseMapper<Udict> {
}

测试类

package com.hejiawang.sharding;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.hejiawang.sharding.entity.Course;
import com.hejiawang.sharding.entity.Udict;
import com.hejiawang.sharding.entity.User;
import com.hejiawang.sharding.mapper.CourseMapper;
import com.hejiawang.sharding.mapper.UdictMapper;
import com.hejiawang.sharding.mapper.UserMapper;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest
public class ShardingApplicationTests {
//  注入mapper
    @Autowired
    private CourseMapper courseeMapper;
    @Autowired
    private UserMapper userMapper;
    @Autowired
    private UdictMapper udictMapper;
//    ===============测试公共表=================
    @Test
    public void addDict(){
        Udict udict = new Udict();
        udict.setUstatus("状态非常好");
        udict.setUvalue("已启用");
        udictMapper.insert(udict);
    }
    @Test
    public void deleteDict(){
        QueryWrapper<Udict> wrapper = new QueryWrapper<>();
        wrapper.eq("dictid",754449834907271169L);
        udictMapper.delete(wrapper);
    }

//    ===============测试垂直分库=================
    @Test
    public void addUserDb(){
        User user = new User();
        user.setUsername("飞哥");
        user.setUstatus("牛逼");
        userMapper.insert(user);
    }

        @Test
        public void findUserDb(){
            QueryWrapper<User> wrapper = new QueryWrapper();
            wrapper.eq("user_id",754389540776443905L);
            User user = userMapper.selectOne(wrapper);
            System.out.println(user);
        }
//    ===============测试水平分库=================
    @Test
    public void addCourseDb(){
            Course course = new Course();
            course.setCname("C++");
//            分库根据user_id
            course.setUserId(100L);
            course.setCstatus("Normal");
            courseeMapper.insert(course);
    }

    @Test
    public void findCourseDb(){
        QueryWrapper<Course> wrapper = new QueryWrapper();
//        wrapper.eq("cid",754034711998758913L);
        wrapper.eq("user_id",100L);
        wrapper.eq("cid",754375827029753857L);
        Course course = courseeMapper.selectOne(wrapper);
        System.out.println(course);
    }
//    ===============测试水平分表=================
//    添加课程
    @Test
    public void addCourse(){
        for (int i = 0 ; i <=10 ; i++){
            Course course = new Course();
            course.setCname("C语言");
            course.setUserId(100L);
            course.setCstatus("Normal"+i);
            courseeMapper.insert(course);
        }
    }

//    查询课程方法
    @Test
    public void findCourse(){
        QueryWrapper<Course> wrapper = new QueryWrapper();
//        wrapper.eq("cid",754034711998758913L);
        wrapper.eq("cid",754034712887951360L);
        Course course = courseeMapper.selectOne(wrapper);
        System.out.println(course);
    }
}

调用addDict（）方法，所有配置数据源下的t_udict表都插入了相同的数据




调用deleteDict（）方法，生成3条删除sql，所有数据源中的表数据都删除了

8.Sharding-jdbc读写分离

1.读写分离概念

sharding-jdbc通过对sql语句语义分析，实现读写分离过程，不会做数据库同步

2.mysql配置读写分离

参考前面文章
https://blog.csdn.net/Persistence___/article/details/123215121?spm=1001.2014.3001.5501

3.sharding-jdbc操作

User

package com.hejiawang.sharding.entity;

import com.baomidou.mybatisplus.annotation.TableName;
import lombok.Data;

/**
 * @description:
 * @author: Mr.Wang
 * @create: 2022-07-14 16:33
 **/
@Data
@TableName(value = "t_user") //指定对应表
public class User {
    private Long userId;
    private String username;
    private String ustatus;
}

UserMapper

package com.hejiawang.sharding.mapper;

import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.hejiawang.sharding.entity.User;
import org.springframework.stereotype.Repository;
@Repository
public interface UserMapper extends BaseMapper<User> {
}

application配置

# shardingjdbc分片策略
#配置数据源，给数据源起名称,水平分库
spring.shardingsphere.datasource.names=ds3,s3

#一个实体类对应两张表，覆盖
spring.main.allow-bean-definition-overriding=true

# 配置第三个数据源具体内容，包含连接池，驱动地址，用户名和密码
# user_db主服务器
spring.shardingsphere.datasource.ds3.type=com.alibaba.druid.pool.DruidDataSource
#jdk1.8 com.mysql.cj.jdbc.Driver
#jdk1.8以下 om.mysql.jdbc.Driver
spring.shardingsphere.datasource.ds3.driver-class-name=com.mysql.cj.jdbc.Driver
spring.shardingsphere.datasource.ds3.url=jdbc:mysql://ip:端口/user_db?serverTimezone=Asia/Shanghai
spring.shardingsphere.datasource.ds3.username = xxx
spring.shardingsphere.datasource.ds3.password = xxx

# user_db从服务器
spring.shardingsphere.datasource.s3.type=com.alibaba.druid.pool.DruidDataSource
#jdk1.8 com.mysql.cj.jdbc.Driver
#jdk1.8以下 om.mysql.jdbc.Driver
spring.shardingsphere.datasource.s3.driver-class-name=com.mysql.cj.jdbc.Driver
spring.shardingsphere.datasource.s3.url=jdbc:mysql://ip:端口/user_db?serverTimezone=Asia/Shanghai
spring.shardingsphere.datasource.s3.username = xxx
spring.shardingsphere.datasource.s3.password = xxx

# 主库从库逻辑数据源定义 ds3为user_db
spring.shardingsphere.sharding.master-slave-rules.ms3.master-data-source-name=ds3
spring.shardingsphere.sharding.master-slave-rules.ms3.slave-data-source-names=s3
# 配置user_db数据库里面t_user 专库专表
spring.shardingsphere.sharding.tables.t_user.actual-data-nodes=ms3.t_user
spring.shardingsphere.sharding.tables.t_user.key-generator.column=user_id
spring.shardingsphere.sharding.tables.t_user.key-generator.type=snowflake
spring.shardingsphere.sharding.tables.t_user.table-strategy.inline.sharding-column=user_id
spring.shardingsphere.sharding.tables.t_user.table-strategy.inline.algorithm-expression=t_user



#打开sql输出日志
spring.shardingsphere.props.sql.show=true

测试类

package com.hejiawang.sharding;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.hejiawang.sharding.entity.Course;
import com.hejiawang.sharding.entity.Udict;
import com.hejiawang.sharding.entity.User;
import com.hejiawang.sharding.mapper.CourseMapper;
import com.hejiawang.sharding.mapper.UdictMapper;
import com.hejiawang.sharding.mapper.UserMapper;
import org.junit.jupiter.api.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest
public class ShardingApplicationTests {
//  注入mapper
    @Autowired
    private CourseMapper courseeMapper;
    @Autowired
    private UserMapper userMapper;
    @Autowired
    private UdictMapper udictMapper;
//    ===============测试读写分离=================
    @Test
    public void addUserDbMaster(){
        User user = new User();
        user.setUsername("肥宅子");
        user.setUstatus("牛逼！！！");
        userMapper.insert(user);
    }
    @Test
    public void findUserDbSlave(){
        QueryWrapper<User> wrapper = new QueryWrapper();
        wrapper.eq("user_id",754389540776443905L);
        User user = userMapper.selectOne(wrapper);
        System.out.println(user);
    }
//    ===============测试公共表=================
    @Test
    public void addDict(){
        Udict udict = new Udict();
        udict.setUstatus("状态非常好");
        udict.setUvalue("已启用");
        udictMapper.insert(udict);
    }
    @Test
    public void deleteDict(){
        QueryWrapper<Udict> wrapper = new QueryWrapper<>();
        wrapper.eq("dictid",754449834907271169L);
        udictMapper.delete(wrapper);
    }
//    ===============测试垂直分库=================
    @Test
    public void addUserDb(){
        User user = new User();
        user.setUsername("飞哥");
        user.setUstatus("牛逼");
        userMapper.insert(user);
    }

        @Test
        public void findUserDb(){
            QueryWrapper<User> wrapper = new QueryWrapper();
            wrapper.eq("user_id",754389540776443905L);
            User user = userMapper.selectOne(wrapper);
            System.out.println(user);
        }
//    ===============测试水平分库=================
    @Test
    public void addCourseDb(){
            Course course = new Course();
            course.setCname("C++");
//            分库根据user_id
            course.setUserId(100L);
            course.setCstatus("Normal");
            courseeMapper.insert(course);
    }

    @Test
    public void findCourseDb(){
        QueryWrapper<Course> wrapper = new QueryWrapper();
//        wrapper.eq("cid",754034711998758913L);
        wrapper.eq("user_id",100L);
        wrapper.eq("cid",754375827029753857L);
        Course course = courseeMapper.selectOne(wrapper);
        System.out.println(course);
    }
//    ===============测试水平分表=================
//    添加课程
    @Test
    public void addCourse(){
        for (int i = 0 ; i <=10 ; i++){
            Course course = new Course();
            course.setCname("C语言");
            course.setUserId(100L);
            course.setCstatus("Normal"+i);
            courseeMapper.insert(course);
        }
    }

//    查询课程方法
    @Test
    public void findCourse(){
        QueryWrapper<Course> wrapper = new QueryWrapper();
//        wrapper.eq("cid",754034711998758913L);
        wrapper.eq("cid",754034712887951360L);
        Course course = courseeMapper.selectOne(wrapper);
        System.out.println(course);
    }
}

调用addUserDbMaster（）方法，insert方法走的ds3数据源，ds3为主库
调用findUserDbSlave（）方法，select方法走的s3数据源，s3为从库