太强了！这款轻量级中间件几行代码就搞定SpringBoot的分库分表问题
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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：
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，关注公众号互联网架构师，回复关键字2T，获取最新架构视频
package com.macky.springbootshardingjdbc.entity;
import com.baomidou.mybatisplus.annotation.TableName;
import com.baomidou.mybatisplus.extension.activerecord.Model;
import groovy.transform.EqualsAndHashCode;
import lombok.Data;
import lombok.experimental.Accessors;
/**
* @author Macky
* @Title class Book
* @Description: 书籍是实体类
* @date 2019/7/13 15:23
*/
@Data
@EqualsAndHashCode(callSuper = true)
@Accessors(chain = true)
@TableName("book")
public class Book extends Model<Book> {
private int id;
private String name;
private int count;
}开放保存和查询两个接口，代码如下：
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> {
}创建数据库表，DDL语句如下
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;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。
参考资料
官方文档：https://shardingsphere.apache.org/document/current/cn/manual/sharding-jdbc/usage/sharding/
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原文发布时间：2020-07-14
本文作者： Macky_He
本文来自：“互联网架构师”，了解相关信息可以关注“互联网架构师”
