Sharding-JDBC不分库，只分表例子

上一篇介绍的了Sharding-jdbc的读写分离，接下来我们写demo，介绍SpringBoot使用Sharding-JDBC不分库，只分表例子。话不多说，直接写代码。

准备

• SpringBoot 2.1.12
• Sharding-JDBC 4.0.0
• Mybatis 3.x
• Mysql 8.0
• lombok

本文场景介绍

一个数据库，将user表分表分为四个一样的表，根据取模算法分别向user0-3的表里插入数据。

POM文件

pom文件引入如下相关依赖：

<?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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>cn.cicoding</groupId>
        <artifactId>shardingsphere-example</artifactId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <groupId>cn.cicoding</groupId>
    <artifactId>sharding-jdbc-table</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>sharding-jdbc-table</name>
    <description>Demo project for Spring Boot</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.apache.shardingsphere</groupId>
            <artifactId>sharding-jdbc-spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.0.1</version>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <optional>true</optional>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

相关代码实现

Controller代码

package cn.cicoding.controller;

import cn.cicoding.model.User;
import cn.cicoding.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class UserController {

    @Autowired
    private UserService userService;

    @GetMapping("/users")
    public Object list() {
        return userService.list();
    }

    @GetMapping("/add")
    public Object add() {
        for (long i = 0; i < 100; i++) {
            User user = new User();
            user.setId(i);
            user.setCity("深圳");
            user.setName("李四"+ i);
            userService.add(user);
        }
        return "success";
    }

    @GetMapping("/users/{id}")
    public Object get(@PathVariable Long id) {
        return userService.findById(id);
    }

    @GetMapping("/users/query")
    public Object get(String name) {
        return userService.findByName(name);
    }

}

Service代码

package cn.cicoding.service;

import cn.cicoding.model.User;

import java.util.List;

public interface UserService {

	List<User> list();
	
	Long add(User user);
	
	User findById(Long id);
	
	User findByName(String name);
	
}

ServiceImpl代码

package cn.cicoding.service.impl;

import cn.cicoding.dao.UserDaoMapper;
import cn.cicoding.model.User;
import cn.cicoding.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserServiceImpl implements UserService {

	@Autowired
	private UserDaoMapper userDao;
	
	public List<User> list() {
		List<User> list = userDao.list();
		return list;
	}

	public Long add(User user) {
		return userDao.addUser(user);
	}

	@Override
	public User findById(Long id) {
		return userDao.findById(id);
	}

	@Override
	public User findByName(String name) {
		return userDao.findByName(name);
	}

}

Dao代码

package cn.cicoding.dao;

import cn.cicoding.model.User;
import org.apache.ibatis.annotations.Mapper;

import java.util.List;

@Mapper
public interface UserDaoMapper {
    Long addUser(User user);

    List<User> list();

    User findById(Long id);

    User findByName(String name);
}

Mapper.xml代码实现

<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="cn.cicoding.dao.UserDaoMapper">
    
    <insert id="addUser">
        INSERT INTO user (
          id, city, name
        )
        VALUES (
        #{id,jdbcType=INTEGER},
        #{city,jdbcType=VARCHAR},
        #{name,jdbcType=VARCHAR}
        )
    </insert>
   
    <select id="list" resultType="cn.cicoding.model.User">
        SELECT u.* FROM user u
    </select>
	
	<select id="findById" resultType="cn.cicoding.model.User">
        SELECT u.* FROM user u WHERE u.id=#{id,jdbcType=INTEGER}
    </select>
    
    <select id="findByName" resultType="cn.cicoding.model.User">
        SELECT u.* FROM user u WHERE u.name=#{name,jdbcType=VARCHAR}
    </select>
    
</mapper>

实体类

package cn.cicoding.model;

import lombok.Data;

import java.io.Serializable;

@Data
public class User implements Serializable {

	private static final long serialVersionUID = -1205226416664488559L;
	
	private Long id;

	private String city = "";
	
	private String name = "";

	
}

到这我们完成了基本的代码编写，由于sharding-jdbc是jar包，我们来看主要的配置信息

#使用取模的方式来实现表分片
server.port=8084

# mybatis对应的映射文件路径
mybatis.mapper-locations=classpath:mapper/*.xml
# mybatis对应的实体类
mybatis.type-aliases-package=cn.cicoding.model

spring.shardingsphere.datasource.names=ds
spring.shardingsphere.datasource.ds.type=com.zaxxer.hikari.HikariDataSource
spring.shardingsphere.datasource.ds.driver-class-name=com.mysql.cj.jdbc.Driver
spring.shardingsphere.datasource.ds.jdbc-url=jdbc:mysql://localhost:3309/ds_0?useSSL=false&useUnicode=true&characterEncoding=utf8&serverTimezone=UTC
spring.shardingsphere.datasource.ds.username=root
spring.shardingsphere.datasource.ds.password=root

# 展示sql打印
spring.shardingsphere.props.sql.show=true

# 自定义分表算法
#spring.shardingsphere.sharding.tables.user.table-strategy.standard.sharding-column=id
#spring.shardingsphere.sharding.tables.user.table-strategy.standard.precise-algorithm-class-name=com.example.MyCustomShardingAlgorithm

# 分表配置
spring.shardingsphere.sharding.tables.user.actual-data-nodes=ds.user_$->{0..3}
# inline 表达式 （id类型转换 ->  id.longValue() -> user_${id.longValue() % 4}）
spring.shardingsphere.sharding.tables.user.table-strategy.inline.sharding-column=id
spring.shardingsphere.sharding.tables.user.table-strategy.inline.algorithm-expression=user_$->{id % 4}
spring.shardingsphere.sharding.tables.user.key-generator.column=id
spring.shardingsphere.sharding.tables.user.key-generator.type=SNOWFLAKE

启动类

package cn.cicoding;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class ShardingJdbcDemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(ShardingJdbcDemoApplication.class, args);
	}

}

测试演示

启动启动类，访问http://localhost:8084/add

查看数据库中user_0，user_1，user_2，user_3中每个数据库库中都有数据，且id都相差4

我们看到DataSources是master节点主库

我们再次访问http://localhost:8084/users

看到数据库中的数据user_0，user_1，user_2，user_3中都查询出来了，实现了不分库分表策略！

到此我们就实现了sharding-jdbc主从读写分离实现，更多配置请参考此处！