1、前言

這是sharding-jdbc的第三篇教程，前兩篇介紹了Mysql的安裝，Mysql的主從同步，這篇我要實現如何通過java代碼實現主從庫的讀寫分離，廢話不多說，開搞。

2、sharding-jdbc

開始之前，先看下sharding-jdbc的介紹和架構，我使用的是4.x版本，所以我們看4.x版本的文檔。

3、建表

在主庫中執行，從庫會自動生成表，因為我們已經配置主從同步。

DROP TABLE IF EXISTS `user`; CREATE TABLE `user` (`id` int(10) NOT NULL AUTO_INCREMENT,`username` varchar(12) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,`password` varchar(30) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,PRIMARY KEY (`id`) USING BTREE,INDEX `idx-username`(`username`) USING BTREE ) ENGINE = InnoDB AUTO_INCREMENT = 1 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

4、pom依賴

<?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>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.5.2</version><relativePath/> <!-- lookup parent from repository --></parent><groupId>com.ckj</groupId><artifactId>shardingsphere-jdbc-lwh</artifactId><version>0.0.1-SNAPSHOT</version><name>shardingsphere-jdbc-lwh</name><description>分庫分表測試項目</description><properties><java.version>1.8</java.version><sharding-sphere.version>4.0.0-RC1</sharding-sphere.version><hutool-all.version>5.4.7</hutool-all.version><guava.version>19.0</guava.version><HikariCP.version>4.0.3</HikariCP.version><mybatis-plus.version>3.1.2</mybatis-plus.version></properties><dependencies><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><dependency><groupId>cn.hutool</groupId><artifactId>hutool-all</artifactId><version>${hutool-all.version}</version></dependency><dependency><groupId>com.google.guava</groupId><artifactId>guava</artifactId><version>${guava.version}</version></dependency><dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId></dependency><dependency><groupId>com.baomidou</groupId><artifactId>mybatis-plus-boot-starter</artifactId><version>${mybatis-plus.version}</version></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId></dependency><!-- 分庫分表--><dependency><groupId>org.apache.shardingsphere</groupId><artifactId>sharding-jdbc-spring-boot-starter</artifactId><version>${sharding-sphere.version}</version></dependency><dependency><groupId>org.apache.shardingsphere</groupId><artifactId>sharding-core-common</artifactId><version>${sharding-sphere.version}</version></dependency><!-- 分庫分表 end--></dependencies><build><plugins><plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><configuration><excludes><exclude><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId></exclude></excludes></configuration></plugin></plugins></build></project>

5、目錄結構

6、主要配置

# 配置真實數據源 spring.shardingsphere.datasource.names=ds0,ds1,ds2# 配置第 1 個數據源 spring.shardingsphere.datasource.ds0.type=com.zaxxer.hikari.HikariDataSource spring.shardingsphere.datasource.ds0.driver-class-name=com.mysql.cj.jdbc.Driver spring.shardingsphere.datasource.ds0.jdbc-url=jdbc:mysql://node1:3306/cool?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone = GMT spring.shardingsphere.datasource.ds0.username=root spring.shardingsphere.datasource.ds0.password=123456# 配置第 2 個數據源 spring.shardingsphere.datasource.ds1.type=com.zaxxer.hikari.HikariDataSource spring.shardingsphere.datasource.ds1.driver-class-name=com.mysql.cj.jdbc.Driver spring.shardingsphere.datasource.ds1.jdbc-url=jdbc:mysql://node2:3306/cool?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone = GMT spring.shardingsphere.datasource.ds1.username=root spring.shardingsphere.datasource.ds1.password=123456# 配置第 3 個數據源 spring.shardingsphere.datasource.ds2.type=com.zaxxer.hikari.HikariDataSource spring.shardingsphere.datasource.ds2.driver-class-name=com.mysql.cj.jdbc.Driver spring.shardingsphere.datasource.ds2.jdbc-url=jdbc:mysql://node3:3306/cool?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone = GMT spring.shardingsphere.datasource.ds2.username=root spring.shardingsphere.datasource.ds2.password=123456#---------------------配置讀寫分離--------------------------------------- #設置讀的時候采用那種算法，round_robin代表輪詢 spring.shardingsphere.masterslave.load-balance-algorithm-type=round_robin spring.shardingsphere.masterslave.name=ms #設置主庫的名稱，來源于上面的配置 spring.shardingsphere.masterslave.master-data-source-name=ds0 #設置從庫的名稱，來源于上面的配置 spring.shardingsphere.masterslave.slave-data-source-names=ds1,ds2 #---------------------配置讀寫分離---------------------------------------server.port= 8085 #------------------------------mybatisPlus配置---------------------------- mybatis-plus.mapper-locations=classpath*:/mappers/*.xml mybatis-plus.type-aliases-package=com.ckj.sharding.sphere.jdbc.lwh.entity #------------------------------mybatisPlus配置----------------------------#多個數據源必須要配置的，允許類型重復 spring.main.allow-bean-definition-overriding=true #打印執行SQL spring.shardingsphere.props.sql.show=true

7、xml和dao代碼

<?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="com.ckj.sharding.sphere.jdbc.lwh.dao.UserMapper"><resultMap id="baseResultMap" type="com.ckj.sharding.sphere.jdbc.lwh.entity.User"><result column="id" property="id" jdbcType="INTEGER" /><result column="username" property="username" jdbcType="VARCHAR" /><result column="password" property="password" jdbcType="VARCHAR" /></resultMap><insert id="addUser">INSERT INTO user (username, password)VALUES (#{username,jdbcType=VARCHAR},#{password,jdbcType=VARCHAR})</insert><select id="list" resultMap="baseResultMap">SELECT u.* FROM user u<where><if test="username != null and username != ''">username = #{username}</if></where></select></mapper> package com.ckj.sharding.sphere.jdbc.lwh.dao;import com.ckj.sharding.sphere.jdbc.lwh.entity.User; import org.apache.ibatis.annotations.Mapper; import org.apache.ibatis.annotations.Param;import java.util.List;/*** @Author: lwh* @Date: 2021/6/25* @Description:**/ @Mapper public interface UserMapper {Long addUser(User user);List<User> list(@Param("username") String username); }

8、接口代碼

package com.ckj.sharding.sphere.jdbc.lwh.controller;import com.ckj.sharding.sphere.jdbc.lwh.entity.User; import com.ckj.sharding.sphere.jdbc.lwh.service.UserService; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.GetMapping; import org.springframework.web.bind.annotation.RequestParam; import org.springframework.web.bind.annotation.RestController;/*** @Author: lwh* @Date: 2021/6/26* @Description:**/ @RestController public class UserController {@Autowiredprivate UserService userService;@GetMapping("/users")public Object list( @RequestParam String username) {return userService.list(username);}@GetMapping("/add")public Object add( @RequestParam String username, @RequestParam String password) {User user = new User();user.setUsername(username);user.setPassword(password);return userService.addUser(user);} }

9、啟動類

package com.ckj.sharding.sphere.jdbc.lwh;import org.mybatis.spring.annotation.MapperScan; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplication @MapperScan(basePackages="com.ckj.sharding.sphere.jdbc.lwh.dao.*") public class ShardingsphereJdbcLwhApplication {public static void main(String[] args) {SpringApplication.run(ShardingsphereJdbcLwhApplication.class, args);}}

10、插入日志

11、查詢多次，從庫輪詢效果

12、結束語

至此我就實現了讀寫分離的效果，后面會實現讀寫分離+分表的功能

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