太强了！这款轻量级的数据库中间件完美解决了SpringBoot中分库分表问题

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。

作者能力有限，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！这款轻量级的数据库中间件完美解决了SpringBoot中分库分表问题

POM.xml文件如下：

<?xml version="1.0" encoding="UTF-8"?>

4.0.0 org.springframework.boot spring-boot-starter-parent 2.1.6.RELEASE com.macky spring-boot-shardingjdbc 0.0.1-SNAPSHOT spring-boot-shardingjdbc Demo project for spring-boot-shardingjdbc

<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>

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 */ @Data @EqualsAndHashCode(callSuper = true) @Accessors(chain = true) @TableName(“book”) public class Book extends Model { 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 */ @RestController public class BookController {

@Autowired BookService bookService;

@RequestMapping(value = “/book”, method = RequestMethod.GET) public List 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 getBookList() { return baseMapper.selectList(Wrappers.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 { }

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=dbKaTeX parse error: Expected group after '_' at position 14: ->{0..2}.book_̲->{0…1} 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 % 2}

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

demo的github地址：

https://github.com/Macky-He/spring-boot–shardingsphere-examples

如各位觉得有帮助的话，还请给个star鼓励鼓励博主，谢谢！

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。 高质量编程视频：shangyepingtai.xin

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