太强了！这款轻量级中间件几行代码搞定SpringBoot的分库分表问题

一、 Sharding-jdbc简介

Sharding-jdbc是开源的数据库操作中间件；定位为轻量级Java框架，在Java的JDBC层提供的额外服务。它使用客户端直连数据库，以jar包形式提供服务，无需额外部署和依赖，可理解为增强版的JDBC驱动，完全兼容JDBC和各种ORM框架。

官方文档地址：https://shardingsphere.apache.org/document/current/cn/overview

本文demo实现了分库分表功能。如有错误，欢迎各位在评论中指出。不胜感激！

二、项目结构

首先创建一个一般的Spring boot项目，项目采用三层架构，结构图如下：

太强了！这款轻量级中间件几行代码搞定SpringBoot的分库分表问题
POM.xml文件如下：

<?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 http://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>2.1.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.macky</groupId>
    <artifactId>spring-boot-shardingjdbc</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>spring-boot-shardingjdbc</name>
    <description>Demo project for spring-boot-shardingjdbc</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>
        <!--mysql-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <!--Mybatis-Plus-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.1.1</version>
        </dependency>
        <!--shardingsphere start-->
        <!-- for spring boot -->
        <dependency>
            <groupId>io.shardingsphere</groupId>
            <artifactId>sharding-jdbc-spring-boot-starter</artifactId>
            <version>3.1.0</version>
        </dependency>
        <!-- for spring namespace -->
        <dependency>
            <groupId>io.shardingsphere</groupId>
            <artifactId>sharding-jdbc-spring-namespace</artifactId>
            <version>3.1.0</version>
        </dependency>
        <!--shardingsphere end-->
        <!--lombok-->
        <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>

实体类以书本为例

package com.macky.springbootshardingjdbc.controller;
import com.macky.springbootshardingjdbc.entity.Book;
import com.macky.springbootshardingjdbc.service.BookService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;
import java.util.List;
/**
 * @author Macky
 * @Title class BookController
 * @Description: TODO
 * @date 2019/7/12 20:53
 */
@RestController
public class BookController {
    @Autowired
    BookService bookService;
    @RequestMapping(value = "/book", method = RequestMethod.GET)
    public List<Book> getItems(){
        return bookService.getBookList();
    }
    @RequestMapping(value = "/book",method = RequestMethod.POST)
    public Boolean saveItem(Book book){
        return bookService.save(book);
    }
}
BookServiceImpl.java
package com.macky.springbootshardingjdbc.service.impl;
import com.baomidou.mybatisplus.core.toolkit.Wrappers;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.macky.springbootshardingjdbc.entity.Book;
import com.macky.springbootshardingjdbc.mapper.BookMapper;
import com.macky.springbootshardingjdbc.service.BookService;
import org.springframework.stereotype.Service;
import java.util.List;
/**
 * @author Macky
 * @Title class BookServiceImpl
 * @Description: TODO
 * @date 2019/7/12 20:47
 */
@Service
public class BookServiceImpl extends ServiceImpl<BookMapper, Book> implements BookService {
    @Override
    public List<Book> getBookList() {
        return baseMapper.selectList(Wrappers.<Book>lambdaQuery());
    }
    @Override
    public boolean save(Book book) {
        return super.save(book);
    }
}
BookMapper.java
package com.macky.springbootshardingjdbc.mapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.macky.springbootshardingjdbc.entity.Book;
/**
 * @author Macky
 * @Title class BookMapper
 * @Description: TODO
 * @date 2019/7/12 20:46
 */
public interface BookMapper extends BaseMapper<Book> {
}

开放保存和查询两个接口，代码如下：

创建数据库表数据
CREATE DATABASE IF NOT EXISTS `db0`;
USE `db0`;
DROP TABLE IF EXISTS `book_0`;
CREATE TABLE `book_0` (
  `id` INT ( 11 ) NOT NULL,
  `name` VARCHAR ( 255 ) DEFAULT NULL,
  `count` INT ( 11 ) DEFAULT NULL,
  PRIMARY KEY ( `id` ) 
) ENGINE = INNODB DEFAULT CHARSET = utf8mb4;
DROP TABLE IF EXISTS `book_1`;
CREATE TABLE `book_1` (
  `id` INT ( 11 ) NOT NULL,
  `name` VARCHAR ( 255 ) DEFAULT NULL,
  `count` INT ( 11 ) DEFAULT NULL,
  PRIMARY KEY ( `id` ) 
) ENGINE = INNODB DEFAULT CHARSET = utf8mb4;
CREATE DATABASE IF NOT EXISTS `db1`;
USE `db1`;
DROP TABLE IF EXISTS `book_0`;
CREATE TABLE `book_0` (
  `id` INT ( 11 ) NOT NULL,
  `name` VARCHAR ( 255 ) DEFAULT NULL,
  `count` INT ( 11 ) DEFAULT NULL,
  PRIMARY KEY ( `id` ) 
) ENGINE = INNODB DEFAULT CHARSET = utf8mb4;
DROP TABLE IF EXISTS `book_1`;
CREATE TABLE `book_1` (
  `id` INT ( 11 ) NOT NULL,
  `name` VARCHAR ( 255 ) DEFAULT NULL,
  `count` INT ( 11 ) DEFAULT NULL,
  PRIMARY KEY ( `id` ) 
) ENGINE = INNODB DEFAULT CHARSET = utf8mb4;
CREATE DATABASE IF NOT EXISTS `db2`;
USE `db2`;
DROP TABLE IF EXISTS `book_0`;
CREATE TABLE `book_0` (
  `id` INT ( 11 ) NOT NULL,
  `name` VARCHAR ( 255 ) DEFAULT NULL,
  `count` INT ( 11 ) DEFAULT NULL,
  PRIMARY KEY ( `id` ) 
) ENGINE = INNODB DEFAULT CHARSET = utf8mb4;
DROP TABLE IF EXISTS `book_1`;
CREATE TABLE `book_1` (
  `id` INT ( 11 ) NOT NULL,
  `name` VARCHAR ( 255 ) DEFAULT NULL,
  `count` INT ( 11 ) DEFAULT NULL,
  PRIMARY KEY ( `id` ) 
) ENGINE = INNODB DEFAULT CHARSET = utf8mb4;

创建数据库表，DDL语句如下

# 数据源 db0,db1,db2
sharding.jdbc.datasource.names=db0,db1,db2
# 第一个数据库
sharding.jdbc.datasource.db0.type=com.zaxxer.hikari.HikariDataSource
sharding.jdbc.datasource.db0.driver-class-name=com.mysql.cj.jdbc.Driver
sharding.jdbc.datasource.db0.jdbc-url=jdbc:mysql://localhost:3306/db0?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
sharding.jdbc.datasource.db0.username=root
sharding.jdbc.datasource.db0.password=Aa123456
# 第二个数据库
sharding.jdbc.datasource.db1.type=com.zaxxer.hikari.HikariDataSource
sharding.jdbc.datasource.db1.driver-class-name=com.mysql.cj.jdbc.Driver
sharding.jdbc.datasource.db1.jdbc-url=jdbc:mysql://localhost:3306/db1?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
sharding.jdbc.datasource.db1.username=root
sharding.jdbc.datasource.db1.password=Aa123456
# 第三个数据库
sharding.jdbc.datasource.db2.type=com.zaxxer.hikari.HikariDataSource
sharding.jdbc.datasource.db2.driver-class-name=com.mysql.cj.jdbc.Driver
sharding.jdbc.datasource.db2.jdbc-url=jdbc:mysql://localhost:3306/db2?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
sharding.jdbc.datasource.db2.username=root
sharding.jdbc.datasource.db2.password=Aa123456
# 水平拆分的数据库（表） 配置分库 + 分表策略 行表达式分片策略
# 分库策略
sharding.jdbc.config.sharding.default-database-strategy.inline.sharding-column=id
sharding.jdbc.config.sharding.default-database-strategy.inline.algorithm-expression=db$->{id % 3}
# 分表策略 其中book为逻辑表 分表主要取决于id行
sharding.jdbc.config.sharding.tables.book.actual-data-nodes=db$->{0..2}.book_$->{0..2}
sharding.jdbc.config.sharding.tables.book.table-strategy.inline.sharding-column=count
# 分片算法表达式
sharding.jdbc.config.sharding.tables.book.table-strategy.inline.algorithm-expression=book_$->{count % 3}
# 主键 UUID 18位数 如果是分布式还要进行一个设置 防止主键重复
#sharding.jdbc.config.sharding.tables.user.key-generator-column-name=id
# 打印执行的数据库以及语句
sharding.jdbc.config.props..sql.show=true
spring.main.allow-bean-definition-overriding=true
#读写分离
sharding.jdbc.datasource.dsmaster =
配置分库分表策略application.properties：

# 数据源 db0,db1,db2
sharding.jdbc.datasource.names=db0,db1,db2
# 第一个数据库
sharding.jdbc.datasource.db0.type=com.zaxxer.hikari.HikariDataSource
sharding.jdbc.datasource.db0.driver-class-name=com.mysql.cj.jdbc.Driver
sharding.jdbc.datasource.db0.jdbc-url=jdbc:mysql://localhost:3306/db0?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
sharding.jdbc.datasource.db0.username=root
sharding.jdbc.datasource.db0.password=Aa123456
# 第二个数据库
sharding.jdbc.datasource.db1.type=com.zaxxer.hikari.HikariDataSource
sharding.jdbc.datasource.db1.driver-class-name=com.mysql.cj.jdbc.Driver
sharding.jdbc.datasource.db1.jdbc-url=jdbc:mysql://localhost:3306/db1?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
sharding.jdbc.datasource.db1.username=root
sharding.jdbc.datasource.db1.password=Aa123456
# 第三个数据库
sharding.jdbc.datasource.db2.type=com.zaxxer.hikari.HikariDataSource
sharding.jdbc.datasource.db2.driver-class-name=com.mysql.cj.jdbc.Driver
sharding.jdbc.datasource.db2.jdbc-url=jdbc:mysql://localhost:3306/db2?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
sharding.jdbc.datasource.db2.username=root
sharding.jdbc.datasource.db2.password=Aa123456
# 水平拆分的数据库（表） 配置分库 + 分表策略 行表达式分片策略
# 分库策略
sharding.jdbc.config.sharding.default-database-strategy.inline.sharding-column=id
sharding.jdbc.config.sharding.default-database-strategy.inline.algorithm-expression=db$->{id % 3}
# 分表策略 其中book为逻辑表 分表主要取决于id行
sharding.jdbc.config.sharding.tables.book.actual-data-nodes=db$->{0..2}.book_$->{0..2}
sharding.jdbc.config.sharding.tables.book.table-strategy.inline.sharding-column=count
# 分片算法表达式
sharding.jdbc.config.sharding.tables.book.table-strategy.inline.algorithm-expression=book_$->{count % 3}
# 主键 UUID 18位数 如果是分布式还要进行一个设置 防止主键重复
#sharding.jdbc.config.sharding.tables.user.key-generator-column-name=id
# 打印执行的数据库以及语句
sharding.jdbc.config.props..sql.show=true
spring.main.allow-bean-definition-overriding=true
#读写分离
sharding.jdbc.datasource.dsmaster =

接口测试使用postman

示例：GET请求------>http://localhost:8080/book POST请求：------->http://localhost:8080/book?id=1&name=java编程思想&count=8

三、总结

分库分表实现按照官方文档做一个demo是第一步，如需深入还需要研究源码，

研究架构，研究思想；此文仅作为入门demo搭建指南，如需深入理解，还请移步

至官方文档。
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