一、 Sharding-jdbc簡介

Sharding-jdbc是開源的數據庫操作中間件；定位為輕量級Java框架，在Java的JDBC層提供的額外服務。它使用客戶端直連數據庫，以jar包形式提供服務，無需額外部署和依賴，可理解為增強版的JDBC驅動，完全兼容JDBC和各種ORM框架。

官方文檔地址：https://shardingsphere.apache.org/document/current/cn/overview

本文demo實現了分庫分表功能。如有錯誤，歡迎各位在評論中指出。不勝感激！

二、項目結構

首先創建一個一般的Spring boot項目，項目采用三層架構，結構圖如下：

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>

實體類以書本為例

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: 書籍是實體類

* @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;}

開放保存和查詢兩個接口，代碼如下：

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> {

}

創建數據庫表，DDL語句如下

創建數據庫表數據

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;

配置分庫分表策略application.properties：

# 數據源 db0,db1,db2

sharding.jdbc.datasource.names=db0,db1,db2

# 第一個數據庫

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

# 第二個數據庫

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

# 第三個數據庫

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

# 水平拆分的數據庫（表） 配置分庫 + 分表策略 行表達式分片策略

# 分庫策略

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為邏輯表 分表主要取決于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

# 分片算法表達式

sharding.jdbc.config.sharding.tables.book.table-strategy.inline.algorithm-expression=book_$->{count % 3}

# 主鍵 UUID 18位數 如果是分布式還要進行一個設置 防止主鍵重復

#sharding.jdbc.config.sharding.tables.user.key-generator-column-name=id

# 打印執行的數據庫以及語句

sharding.jdbc.config.props..sql.show=true

spring.main.allow-bean-definition-overriding=true

#讀寫分離

sharding.jdbc.datasource.dsmaster =

接口測試使用postman

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

三、總結

分庫分表實現按照官方文檔做一個demo是第一步，如需深入還需要研究源碼，

研究架構，研究思想；此文僅作為入門demo搭建指南，如需深入理解，還請移步

至官方文檔。

參考資料

• 官方文檔：https://shardingsphere.apache.org/document/current/cn/manual/sharding-jdbc/usage/sharding/