使用Sharding-JDBC 分库分表-CFANZ编程社区

当mysql单表数据量比较大时往往需要分库分表，Sharding-JDBC是当当网开源的数据库分库分表中间件。Sharding-JDBC定位为轻量级java框架，使用客户端直连数据库，以jar包形式提供服务，无proxy代理层，无需额外部署，无其他依赖，DBA也无需改变原有的运维方式。本文主要讲述该框架与spring+mybatis的整合使用。

1.准备工作#

由于是分库分表，所以需要在不同的数据库建立相同的表。分别在sharding_0,sharding_1两个数据库中建立t_user0,t_user1,t_user2三张表，需要用到的SQL语句如下:

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SET FOREIGN_KEY_CHECKS=0;

DROP TABLE IF EXISTS `t_user_0`;
CREATE TABLE `t_user_0` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` int(11) NOT NULL,
  `name` varchar(255) NOT NULL,
  `age` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `t_user_1`;
CREATE TABLE `t_user_1` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` int(11) NOT NULL,
  `name` varchar(255) NOT NULL,
  `age` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

DROP TABLE IF EXISTS `t_user_2`;
CREATE TABLE `t_user_2` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `user_id` int(11) NOT NULL,
  `name` varchar(255) NOT NULL,
  `age` int(11) NOT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

项目的整体结构如下图所示：

需要用到的sharding-jdbc的依赖如下所示：

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<dependency> <groupId>io.shardingjdbcgroupId> <artifactId>sharding-jdbc-coreartifactId> <version>${latest.release.version}version> dependency>

2.代码详解#

代码结构如上图所示，Mapper,Service层和普通的SSM项目一样，无需做改变，主要是增加了algorithm下面的两个文件，一个是分库策略，一个是分表策略。然后spring的配置文件稍稍做了修改，spring-database.xml设置的是数据库的连接信息。spring-sharding.xml设置的是具体的分库分表信息。

spring-database.xml配置如下所示：

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<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">        <property name="locations">            <list>                <value>classpath:config/resource/jdbc_dev.propertiesvalue>            list>        property>    bean>        
    <bean name="sharding_0" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">        <property name="url" value="${jdbc_url0}" />        <property name="username" value="${jdbc_username0}" />        <property name="password" value="${jdbc_password0}" />

        
        <property name="initialSize" value="0" />        
        <property name="maxActive" value="20" />        
        <property name="minIdle" value="0" />        
        <property name="maxWait" value="60000" />        <property name="validationQuery" value="${validationQuery}" />        <property name="testOnBorrow" value="false" />        <property name="testOnReturn" value="false" />        <property name="testWhileIdle" value="true" />        
        <property name="timeBetweenEvictionRunsMillis" value="60000" />        
        <property name="minEvictableIdleTimeMillis" value="25200000" />        
        <property name="removeAbandoned" value="true" />        
        <property name="removeAbandonedTimeout" value="1800" />        
        <property name="logAbandoned" value="true" />        <property name="filters" value="stat" />    bean>    
    <bean name="sharding_1" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">        <property name="url" value="${jdbc_url1}" />        <property name="username" value="${jdbc_username1}" />        <property name="password" value="${jdbc_password1}" />

        
        <property name="initialSize" value="0" />        
        <property name="maxActive" value="20" />        
        <property name="minIdle" value="0" />        
        <property name="maxWait" value="60000" />        <property name="validationQuery" value="${validationQuery}" />        <property name="testOnBorrow" value="false" />        <property name="testOnReturn" value="false" />        <property name="testWhileIdle" value="true" />        
        <property name="timeBetweenEvictionRunsMillis" value="60000" />        
        <property name="minEvictableIdleTimeMillis" value="25200000" />        
        <property name="removeAbandoned" value="true" />        
        <property name="removeAbandonedTimeout" value="1800" />        
        <property name="logAbandoned" value="true" />        <property name="filters" value="stat" />    bean>

spring-sharding.xml配置如下所示，从下图中可以看到主要是指定了需要分表的策略和分库的策略，然后进行了封装，具体的分库分表策略需要自己编写。

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    <bean id="dataSourceRule" class="com.dangdang.ddframe.rdb.sharding.api.rule.DataSourceRule">        <constructor-arg>            <map>                <entry key="sharding_0" value-ref="sharding_0"/>                <entry key="sharding_1" value-ref="sharding_1"/>            map>        constructor-arg>    bean>    
    
    <bean id="userTableRule" class="com.dangdang.ddframe.rdb.sharding.api.rule.TableRule">        <constructor-arg value="t_user" index="0"/>        <constructor-arg index="1">            <list>                <value>t_user_0value>                <value>t_user_1value>                <value>t_user_2value>            list>        constructor-arg>        <constructor-arg index="2" ref="dataSourceRule"/>        <constructor-arg index="3" ref="userDatabaseShardingStrategy"/>        <constructor-arg index="4" ref="userTableShardingStrategy"/>    bean>    
    
    <bean id="userDatabaseShardingStrategy" class="com.dangdang.ddframe.rdb.sharding.api.strategy.database.DatabaseShardingStrategy">        <constructor-arg index="0" value="user_id"/>        <constructor-arg index="1">            <bean class="com.study.dangdang.sharding.jdbc.algorithm.UserSingleKeyDatabaseShardingAlgorithm" />        constructor-arg>    bean>    
    
    <bean id="userTableShardingStrategy" class="com.dangdang.ddframe.rdb.sharding.api.strategy.table.TableShardingStrategy">        <constructor-arg index="0" value="user_id"/>        <constructor-arg index="1">            <bean class="com.study.dangdang.sharding.jdbc.algorithm.UserSingleKeyTableShardingAlgorithm" />        constructor-arg>    bean>    
    
    <bean id="shardingRule" class="com.dangdang.ddframe.rdb.sharding.api.rule.ShardingRule">        <constructor-arg index="0" ref="dataSourceRule"/>        <constructor-arg index="1">            <list>                <ref bean="userTableRule"/>            list>        constructor-arg>    bean>    
    
    <bean id="shardingDataSource" class="com.dangdang.ddframe.rdb.sharding.api.ShardingDataSource">        <constructor-arg ref="shardingRule"/>    bean>