ShardingSphere之水平分表实战（三）

概述

搭建环境

Springboot2.3.2.RELEASE + Tkmybatis + Sharding-jdbc + Druid

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>2.3.2.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.study</groupId>
    <artifactId>shardingjdbcdemo</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>shardingjdbcdemo</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-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>1.18.14</version>
            <optional>true</optional>
        </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>
        <!-- tkmybatis -->
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper-spring-boot-starter</artifactId>
            <version>2.1.5</version>
        </dependency>
        <dependency>
            <groupId>tk.mybatis</groupId>
            <artifactId>mapper</artifactId>
            <version>4.1.5</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
                <configuration>
                    <excludes>
                        <exclude>
                            <groupId>org.projectlombok</groupId>
                            <artifactId>lombok</artifactId>
                        </exclude>
                    </excludes>
                </configuration>
            </plugin>
        </plugins>
    </build>
</project>

建库、建表

库、表设计：

1. 创建数据库course_db。
2. 在数据库中创建两种表course_1和course_2。
3. 约定规则：如果添加课程id是偶数把数据添加到course_1，奇数添加到course_2。
   新建数据库course_db。
   新建表course_1和course_2。

CREATE TABLE `course_1` (
  `cid` bigint(20) NOT NULL,
  `cname` varchar(50) NOT NULL,
  `user_id` bigint(20) NOT NULL,
  `cstatus` varchar(10) NOT NULL,
  PRIMARY KEY (`cid`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

代码结构

package com.study.shardingjdbcdemo.entity;

import lombok.Data;

@Data
public class Course {
    
	@Id
    private Long cid;
    private String cname;
    @Column(name = "user_id")
    private Long userId;
    private String cstatus;
}

package com.study.shardingjdbcdemo.mapper;

import com.study.shardingjdbcdemo.entity.Course;
import org.springframework.stereotype.Repository;
import tk.mybatis.mapper.common.Mapper;

@Repository
public interface CourseMapper extends Mapper<Course> {
    
}

package com.study.shardingjdbcdemo;

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

@SpringBootApplication
@MapperScan("com.study.shardingjdbcdemo.mapper")
public class ShardingjdbcdemoApplication {
    
    public static void main(String[] args) {
    
        SpringApplication.run(ShardingjdbcdemoApplication.class, args);
    }
}
package com.study.shardingjdbcdemo;

import com.study.shardingjdbcdemo.mapper.CourseMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

@SpringBootTest
class ShardingjdbcdemoApplicationTests {
    
    @Autowired
    private CourseMapper courseMapper;
    @Test
    void contextLoads() {
    
    }
}

配置Sharding-JDBC分片策略

application.properties

# 配置分片策略
# 配置数据源
spring.shardingsphere.datasource.names=m1
spring.shardingsphere.datasource.m1.type=com.alibaba.druid.pool.DruidDataSource
spring.shardingsphere.datasource.m1.driver-class-name=com.mysql.cj.jdbc.Driver
spring.shardingsphere.datasource.m1.url=jdbc:mysql://localhost:3306/course_db?serverTimezone=GMT%2B8
spring.shardingsphere.datasource.m1.username=root
spring.shardingsphere.datasource.m1.password=123456
# 指定course表分布情况,配置表在哪个数据库中,表名称都是什么
spring.shardingsphere.sharding.tables.course.actual-data-nodes=m1.course_$->{
    1..2}
# 指定course主键cid生成策略SNOWFLAKE
spring.shardingsphere.sharding.tables.course.key-generator.column=cid
spring.shardingsphere.sharding.tables.course.key-generator.type=SNOWFLAKE
# 指定分片策略, cid是偶数添加到course_1表中,cid是奇数添加到course_2
spring.shardingsphere.sharding.tables.course.table-strategy.inline.sharding-column=cid
spring.shardingsphere.sharding.tables.course.table-strategy.inline.algorithm-expression=course_$->{
    cid % 2 + 1}
# 打开sql输出日志
spring.shardingsphere.props.sql.show=true

测试

测试用例

package com.study.shardingjdbcdemo;

import com.study.shardingjdbcdemo.entity.Course;
import com.study.shardingjdbcdemo.mapper.CourseMapper;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;

import java.util.List;

@SpringBootTest
class ShardingjdbcdemoApplicationTests {
    

    @Autowired
    private CourseMapper courseMapper;

    @Test
    void add() {
    
        for (int i = 0; i < 10; i++) {
    
            Course course = new Course();
            course.setCname("java");
            course.setUserId(100L);
            course.setCstatus("normal");
            // 注意使用insertSelective，否则会报错，因为sharding-jdbc会自己生成主键字段并拼接到sql中，如果sql语句中带有cid主键就会重复报错
            courseMapper.insertSelective(course);
        }
    }

    @Test
    void query() {
    
        List<Course> courses = courseMapper.selectAll();
        courses.forEach(System.out::println);
    }
}

测试报错

The bean 'dataSource', defined in class path resource [org/apache/shardingsphere/shardingjdbc/spring/boot/SpringBootConfiguration.class], could not be registered. A bean with that name has already been defined in class path resource [com/alibaba/druid/spring/boot/autoconfigure/DruidDataSourceAutoConfigure.class] and overriding is disabled.
Action:
Consider renaming one of the beans or enabling overriding by setting spring.main.allow-bean-definition-overriding=true

解决方案

application.properties中添加配置

# 解决一个Course实体类不能对应两张表的问题
spring.main.allow-bean-definition-overriding=true