场景：不同数据库存在相同的表，保持数据同步

一、创建一个springboot项目,结构如下

二、pom.xml直接粘贴过去(了解一下jar包作用!)

<?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>2.3.2.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>
	<groupId>com.example</groupId>
	<artifactId>shardingsphere_demo</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<name>shardingsphere_demo</name>
	<description>Demo project for Spring Boot</description>

	<properties>
		<java.version>1.8</java.version>
	</properties>

	<dependencies>
	    <!--提供了数据源配置、事务管理、数据访问等等功能-->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-jdbc</artifactId>
		</dependency>

		<!--1.自动发现存在的DataSource-->
		<!--2.利用SqlSessionFactoryBean创建并注册SqlSessionFactory-->
		<!--3.创建并注册SqlSessionTemplate-->
		<!--4.自动扫描Mappers，并注册到Spring上下文环境方便程序的注入使用-->
		<dependency>
			<groupId>org.mybatis.spring.boot</groupId>
			<artifactId>mybatis-spring-boot-starter</artifactId>
			<version>2.1.3</version>
		</dependency>
		
		<!--Druid为监控而生的数据库连接池，它是阿里巴巴开源平台上的一个项目-->
		<dependency>
			<groupId>com.alibaba</groupId>
			<artifactId>druid</artifactId>
			<version>1.1.23</version>
		</dependency>

		<!--核心依赖-sharding-jdbc-->
		<dependency>
			<groupId>org.apache.shardingsphere</groupId>
			<artifactId>sharding-jdbc-spring-boot-starter</artifactId>
			<version>4.1.1</version>
		</dependency>

		<!-- mysql依赖-->
		<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
			<scope>runtime</scope>
		</dependency>
		
		<!-- 测试依赖-->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-test</artifactId>
			<scope>test</scope>
			<exclusions>
				<exclusion>
					<groupId>org.junit.vintage</groupId>
					<artifactId>junit-vintage-engine</artifactId>
				</exclusion>
			</exclusions>
		</dependency>
	</dependencies>

	<build>
		<plugins>
			<!-- 打包插件-->
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
			
			<!--maven里执行测试用例的插件-->
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-surefire-plugin</artifactId>
				<configuration>
					<skipTests>true</skipTests>
				</configuration>
			</plugin>
		</plugins>
	</build>
	
</project>

三、创建实体类

package com.example.demo.test.entity;

public class Config {

    private Integer id;
    private String type;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String type() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

}

四、创建mapper类

package com.example.demo.test.mapper;

import com.example.demo.test.entity.Config;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Mapper;
import org.springframework.stereotype.Repository;

@Repository
@Mapper
public interface ConfigMapper {

    @Insert("insert into config(id,type) values(#{id},#{type})")
    void insertConfig(Config config);

    @Delete("delete from config where id = #{id}")
    void deleteConfig(Integer id);

}

四、修改application.properties配置文件(主要关注一下!)

#mybatis.type-aliases-package来指定POJO扫描包来让mybatis自动扫描到自定义的POJO
mybatis.type-aliases-package=com.example.demo.test

#配置数据源
spring.shardingsphere.datasource.names=ds1,ds2
#配置第一个数据源
spring.shardingsphere.datasource.ds1.type=com.alibaba.druid.pool.DruidDataSource
spring.shardingsphere.datasource.ds1.driver-class-name=com.mysql.jdbc.Driver
spring.shardingsphere.datasource.ds1.url=jdbc:mysql://localhost:3306/test?serverTimezone=UTC
spring.shardingsphere.datasource.ds1.username=root
spring.shardingsphere.datasource.ds1.password=123456

#配置第二个数据源
spring.shardingsphere.datasource.ds2.type=com.alibaba.druid.pool.DruidDataSource
spring.shardingsphere.datasource.ds2.driver-class-name=com.mysql.jdbc.Driver
spring.shardingsphere.datasource.ds2.url=jdbc:mysql://localhost:7306/test?serverTimezone=UTC
spring.shardingsphere.datasource.ds2.username=root
spring.shardingsphere.datasource.ds2.password=123456

#配置公共表
spring.shardingsphere.sharding.broadcast-tables=config
spring.shardingsphere.sharding.tables.dict_order_type.key-generator.column=id
spring.shardingsphere.sharding.tables.dict_order_type.key-generator.type=SNOWFLAKE

#显示sql
spring.shardingsphere.props.sql.show=true

五、数据库手动创建表结构

1.根据上面实体类在两个数据库中分别创建config表

2.分片规则：所有的库都具备相同的表

六、创建测试类

package com.example.demo.test;

import com.example.demo.test.entity.Orders;
import com.example.demo.test.entity.User;
import com.example.demo.test.mapper.OrdersMapper;
import com.example.demo.test.mapper.UserMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
class ShardingsphereDemoApplicationTests {

     @Autowired
    private ConfigMapper configMapper;

    @Test
    public void insertConfig(){
        for (int i = 1; i <= 10 ; i++) {
            Config config = new Config();
            config.setId(i);
            config.setType("config"+i);
            configMapper.insertConfig(config);
        }
    }

    @Test
    public void deleteConfig(){
        configMapper.deleteConfig(1);
    }

}

七、测试

分别执行insertConfig()方法和deleteConfig()方法添加数据，结果如下