【死磕Sharding-jdbc】---基于ssm

用户1655470

发布于 2018-07-24 17:24:06

7920

发布于 2018-07-24 17:24:06

文章被收录于专栏：chenssychenssy

本篇文章讲解如何在ssm（spring、springmvc、mybatis）结构的程序上集成sharding-jdbc（版本为1.5.4.1）进行分库分表；假设分库分表行为如下：

将authuser表分到4个库（user0~user_3）中；
其他表不进行分库分表，保留在default_db库中；

1. POM配置

以spring配置文件为例，新增如下POM配置：

<dependency>    <groupId>com.dangdang</groupId>    <artifactId>sharding-jdbc-core</artifactId>    <version>1.5.4.1</version></dependency><dependency>    <groupId>com.dangdang</groupId>    <artifactId>sharding-jdbc-config-spring</artifactId>    <version>1.5.4.1</version></dependency>

此次集成sharding-jdbc以1.5.4.1版本为例，如果是2.x版本的sharding-jdbc，那么需要将坐标 <groupId>com.dangdang</groupId>修改为 <groupId>io.shardingjdbc</groupId>；另外，如果是yaml配置，那么需要将坐标 <artifactId>sharding-jdbc-config-spring</artifactId>修改为 <artifactId>sharding-jdbc-config-yaml</artifactId>；

2. 配置数据源

spring-datasource.xml配置所有需要的数据源如下--authuser分库分表后需要的4个库user0~user3，以及不分库分表的默认库defaultdb：

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"       xsi:schemaLocation="http://www.springframework.org/schema/beans        http://www.springframework.org/schema/beans/spring-beans.xsd">    <!-- 配置数据源 -->    <bean id="sj_ds_0" class="com.alibaba.druid.pool.DruidDataSource"          init-method="init" destroy-method="close">        <property name="url" value="${sj_user_0.url}" />        <property name="username" value="${sj_user_0.username}" />        <property name="password" value="${sj_user_0.password}" />        <!--druid配置优化可以放在这里-->    </bean>    <!-- 配置数据源 -->    <bean id="sj_ds_1" class="com.alibaba.druid.pool.DruidDataSource"          init-method="init" destroy-method="close">        <property name="url" value="${sj_user_1.url}" />        <property name="username" value="${sj_user_1.username}" />        <property name="password" value="${sj_user_1.password}" />        <!--druid配置优化可以放在这里-->    </bean>    <!-- 配置数据源 -->    <bean id="sj_ds_2" class="com.alibaba.druid.pool.DruidDataSource"          init-method="init" destroy-method="close">        <property name="url" value="${sj_user_2.url}" />        <property name="username" value="${sj_user_2.username}" />        <property name="password" value="${sj_user_2.password}" />        <!--druid配置优化可以放在这里-->    </bean>    <!-- 配置数据源 -->    <bean id="sj_ds_3" class="com.alibaba.druid.pool.DruidDataSource"          init-method="init" destroy-method="close">        <property name="url" value="${sj_user_3.url}" />        <property name="username" value="${sj_user_3.username}" />        <property name="password" value="${sj_user_3.password}" />        <!--druid配置优化可以放在这里-->    </bean>    <!-- 配置数据源 -->    <bean id="sj_ds_default" class="com.alibaba.druid.pool.DruidDataSource"          init-method="init" destroy-method="close">        <property name="url" value="${sj_default.url}" />        <property name="username" value="${sj_default.username}" />        <property name="password" value="${sj_default.password}" />        <!--druid配置优化可以放在这里-->    </bean></beans>

properties配置文件内容如下：

sj_user_0.driver=com.mysql.jdbc.Driversj_user_0.url=jdbc:mysql://localhost:3306/user_0sj_user_0.username=rootsj_user_0.password=RootAfei_1sj_user_1.driver=com.mysql.jdbc.Driversj_user_1.url=jdbc:mysql://localhost:3306/user_1sj_user_1.username=rootsj_user_1.password=RootAfei_1sj_user_2.driver=com.mysql.jdbc.Driversj_user_2.url=jdbc:mysql://localhost:3306/user_2sj_user_2.username=rootsj_user_2.password=RootAfei_1sj_user_3.driver=com.mysql.jdbc.Driversj_user_3.url=jdbc:mysql://localhost:3306/user_3sj_user_3.username=rootsj_user_3.password=RootAfei_1sj_default.driver=com.mysql.jdbc.Driversj_default.url=jdbc:mysql://localhost:3306/default_dbsj_default.username=rootsj_default.password=RootAfei_1

3. 集成sharding数据源

spring-sharding.xml配置如下：

<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans"       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"       xmlns:rdb="http://www.dangdang.com/schema/ddframe/rdb"       xsi:schemaLocation="http://www.springframework.org/schema/beans                        http://www.springframework.org/schema/beans/spring-beans.xsd                        http://www.dangdang.com/schema/ddframe/rdb                        http://www.dangdang.com/schema/ddframe/rdb/rdb.xsd">    <!--数据库sharding策略：以id列进行sharding，sharding逻辑在AuthUserDatabaseShardingAlgorithm中-->    <rdb:strategy id="databaseStrategy" sharding-columns="id"                  algorithm-class="com.crt.fin.ospsso.service.shardingjdbc.AuthUserDatabaseShardingAlgorithm" />    <!--auth_user表sharding策略:无 -->    <!--定义sharding数据源-->    <rdb:data-source id="shardingDataSource">        <!--default-data-source指定默认数据源, 即没有在<rdb:table-rules>申明的logic-table表,        即不需要分库分表的表, 全部走默认数据源-->        <rdb:sharding-rule data-sources="sj_ds_0,sj_ds_1,sj_ds_2,sj_ds_3,sj_ds_default"                           default-data-source="sj_ds_default">            <rdb:table-rules>                <!--auth_user只分库不分表, actual-tables的值一定要加上:sj_ds_${0..3}.,                否则会遍历data-sources, 而sj_ds_default中并没有auth_user表 -->                <rdb:table-rule logic-table="auth_user" actual-tables="sj_ds_${0..3}.auth_user"                                database-strategy="databaseStrategy"/>            </rdb:table-rules>            <rdb:default-database-strategy sharding-columns="none" algorithm-class="com.dangdang.ddframe.rdb.sharding.api.strategy.database.NoneDatabaseShardingAlgorithm"/>            <rdb:default-table-strategy sharding-columns="none" algorithm-class="com.dangdang.ddframe.rdb.sharding.api.strategy.table.NoneTableShardingAlgorithm"/>        </rdb:sharding-rule>        <rdb:props>            <prop key="sql.show">true</prop>            <prop key="executor.size">2</prop>        </rdb:props>    </rdb:data-source>    <!-- 配置sqlSessionFactory -->    <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">        <!---datasource交给sharding-jdbc托管-->        <property name="dataSource" ref="shardingDataSource"/>        <property name="mapperLocations" value="classpath*:mybatis/*Mapper.xml"/>    </bean>    <bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">        <property name="basePackage" value="com.crt.fin.ospsso.dal.mapper"/>        <property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>    </bean></beans>

说明：spring-sharding.xml配置的分库分表规则：authuser表分到id为sjds${0..3}的四个库中，表名保持不变；其他表在id为sjds_default库中，不分库也不分表；集成sharding-jdbc的核心就是将SqlSessionFactoryBean需要的dataSource属性修改为 shardingDataSource，把数据源交给sharding-jdbc处理；

分库逻辑 AuthUserDatabaseShardingAlgorithm的代码很简单，源码如下：

/** * @author wangzhenfei9 * @version 1.0.0 * @since 2018年02月08日 */public class AuthUserDatabaseShardingAlgorithm implements SingleKeyDatabaseShardingAlgorithm<Long> {    private final Logger logger = LoggerFactory.getLogger(this.getClass());    private static final int SHARDING_NUMBER = 4;    @Override    public String doEqualSharding(final Collection<String> availableTargetNames, final ShardingValue<Long> shardingValue) {        for (String each : availableTargetNames) {            if (each.endsWith(shardingValue.getValue() % SHARDING_NUMBER + "")) {                logger.debug("the target database name: {}", each);                return each;            }        }        throw new UnsupportedOperationException();    }    @Override    public Collection<String> doInSharding(final Collection<String> availableTargetNames, final ShardingValue<Long> shardingValue) {        Collection<String> result = new LinkedHashSet<>(availableTargetNames.size());        Collection<Long> values = shardingValue.getValues();        for (Long value : values) {            for (String each : availableTargetNames) {                if (each.endsWith(value % SHARDING_NUMBER + "")) {                    result.add(each);                }            }        }        return result;    }    @Override    public Collection<String> doBetweenSharding(final Collection<String> availableTargetNames, final ShardingValue<Long> shardingValue) {        Collection<String> result = new LinkedHashSet<>(availableTargetNames.size());        Range<Long> range = shardingValue.getValueRange();        for (Long value = range.lowerEndpoint(); value <= range.upperEndpoint(); value++) {            for (String each : availableTargetNames) {                if (each.endsWith(value % SHARDING_NUMBER + "")) {                    result.add(each);                }            }        }        return result;    }}

这段代码参考sharding-jdbc源码中 DatabaseShardingAlgorithm.java接口的实现即可，例如 ModuloDatabaseShardingAlgorithm.java；

4. 注意事项

无法识别sharding-jdbc分库分表规则inline-expression问题，例如： <rdb:table-rulelogic-table="auth_user"actual-tables="sj_ds_${0..3}.auth_user"database-strategy="databaseStrategy"/>

根本原因：根本原因是spring把 ${}当做占位符， ${0..3}这种表达式，spring会尝试去properties文件中找key为 0..3的属性。但是这里是sharding-jdbc分库分表规则的inline表达式，需要spring忽略这种行为。否则会抛出异常: java.lang.IllegalArgumentException: Could not resolve placeholder '0..3' in value "sjds${0..3}.auth_user"
解决办法：配置: <propertyname="ignoreUnresolvablePlaceholders"value="true"/> 或者: <context:property-placeholder****** ignore-unresolvable="true"/>

5. Main测试

Main.java用来测试分库分表是否OK，其源码如下：

/** * @author wangzhenfei9 * @version 1.0.0 * @since 2018年02月08日 */public class Main {    public static void main(String[] args) {        ApplicationContext context = new ClassPathXmlApplicationContext(                "/META-INF/spring/spring-*.xml");        // auth_user有进行分库，        AuthUserMapper authUserMapper = context.getBean(AuthUserMapper.class);        AuthUser authUser = authUserMapper.selectByPrimaryKey(7L);        System.out.println("-----> The auth user: "+JSON.toJSONString(authUser));        // user_permission没有分库分表        UserPermissionMapper userPermissionMapper = context.getBean(UserPermissionMapper.class);        UserPermission userPermission = userPermissionMapper.selectPermissionByUsername("wangzhenfei", "FINANCE_WALLET");        System.out.println("-----< The user permission: "+JSON.toJSONString(userPermission));    }}

AuthUserMapper.selectByPrimaryKey()和UserPermissionMapper.selectPermissionByUsername()的代码和没有分库分表的代码完全一样；

6. 遗留问题

Main方法测试，或者启动服务后的调用测试都没有问题，但是通过junit测试用例访问就会抛出异常，作为一个待解决的遗留问题：

org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'javax.sql.DataSource' available: expected single matching bean but found 6: sj_ds_0,sj_ds_1,sj_ds_2,sj_ds_3,sj_ds_default,shardingDataSource

END

本文参与腾讯云自媒体分享计划，分享自微信公众号。

原始发表：2018-06-29，如有侵权请联系 cloudcommunity@tencent.com 删除

其他

本文分享自 Java技术驿站微信公众号，前往查看

如有侵权，请联系 cloudcommunity@tencent.com 删除。

本文参与腾讯云自媒体分享计划，欢迎热爱写作的你一起参与！

其他

登录后参与评论

0 条评论

热度