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

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/