# 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！
# 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：
> 推荐一个艿艿写的 3000+ Star 的 SpringCloud Alibaba 电商开源项目的仓库：<https://github.com/YunaiV/onemall> # 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
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！
# 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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