20.sharding-jdbc2.0.3整合--基於ssm
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本篇文章講解如何在ssm(spring、springmvc、mybatis)結構的程式上整合sharding-jdbc(版本為2.0.3)進行分庫分表;
假設分庫分錶行為如下:
- 將auth_user表分到4個庫(user_0~user_3)中;
- 其他表不進行分庫分表,保留在default_db庫中;
1. POM配置
以spring配置檔案為例,新增如下POM配置:
<dependency>
<groupId>io.shardingjdbc</groupId>
<artifactId >sharding-jdbc-core</artifactId>
<version>2.0.3</version>
</dependency>
<!--如果通過spring配置, 需要增加如下maven座標-->
<dependency>
<groupId>io.shardingjdbc</groupId>
<artifactId>sharding-jdbc-core-spring-namespace</artifactId>
<version >2.0.3</version>
</dependency>
2. 配置資料來源
spring-datasource.xml配置所有需要的資料來源如下–auth_user分庫分表後需要的4個庫user_0~user_3,以及不分庫分表的預設庫default_db:
<?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">
<!-- 配置資料來源 -->
<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="${sj_user_0.password}" />
<!--druid配置優化可以放在這裡-->
</bean>
<!-- 配置資料來源 -->
<bean id="sj_ds_1" class="com.alibaba.druid.pool.DruidDataSource"
init-method="init" destroy-method="close">
<property name="url" value="${sj_user_1.url}" />
<property name="username" value="${sj_user_1.username}" />
<property name="password" value="${sj_user_1.password}" />
<!--druid配置優化可以放在這裡-->
</bean>
<!-- 配置資料來源 -->
<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="${sj_user_2.password}" />
<!--druid配置優化可以放在這裡-->
</bean>
<!-- 配置資料來源 -->
<bean id="sj_ds_3" class="com.alibaba.druid.pool.DruidDataSource"
init-method="init" destroy-method="close">
<property name="url" value="${sj_user_3.url}" />
<property name="username" value="${sj_user_3.username}" />
<property name="password" value="${sj_user_3.password}" />
<!--druid配置優化可以放在這裡-->
</bean>
<!-- 配置資料來源 -->
<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配置優化可以放在這裡-->
</bean>
</beans>
properties配置檔案內容如下:
sj_user_0.driver=com.mysql.jdbc.Driver
sj_user_0.url=jdbc:mysql://localhost:3306/user_0
sj_user_0.username=root
sj_user_0.password=RootAfei_1
sj_user_1.driver=com.mysql.jdbc.Driver
sj_user_1.url=jdbc:mysql://localhost:3306/user_1
sj_user_1.username=root
sj_user_1.password=RootAfei_1
sj_user_2.driver=com.mysql.jdbc.Driver
sj_user_2.url=jdbc:mysql://localhost:3306/user_2
sj_user_2.username=root
sj_user_2.password=RootAfei_1
sj_user_3.driver=com.mysql.jdbc.Driver
sj_user_3.url=jdbc:mysql://localhost:3306/user_3
sj_user_3.username=root
sj_user_3.password=RootAfei_1
sj_default.driver=com.mysql.jdbc.Driver
sj_default.url=jdbc:mysql://localhost:3306/default_db
sj_default.username=root
sj_default.password=RootAfei_1
3. 整合sharding資料來源
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:sharding="http://shardingjdbc.io/schema/shardingjdbc/sharding"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://shardingjdbc.io/schema/shardingjdbc/sharding
http://shardingjdbc.io/schema/shardingjdbc/sharding/sharding.xsd">
<!--資料庫sharding策略-->
<sharding:standard-strategy id="databaseStrategy" sharding-column="id"
precise-algorithm-class="com.crt.fin.ospsso.service.shardingjdbc.AuthUserDatabaseShardingAlgorithm" />
<!--auth_user表sharding策略:無 -->
<sharding:none-strategy id="noneStrategy" />
<sharding:data-source id="shardingDataSource">
<!--default-data-source指定預設資料來源, 即沒有在<rdb:table-rules>申明的logic-table表,
即不需要分庫分表的表, 全部走預設資料來源-->
<sharding:sharding-rule data-source-names="sj_ds_0,sj_ds_1,sj_ds_2,sj_ds_3,sj_ds_default"
default-data-source-name="sj_ds_default"
default-database-strategy-ref="noneStrategy"
default-table-strategy-ref="noneStrategy">
<sharding:table-rules>
<!--auth_user只分庫不分表, actual-tables的值一定要加上:sj_ds_${0..3}.,
否則會遍歷data-sources, 而sj_ds_default中並沒有auth_user表 -->
<sharding:table-rule logic-table="auth_user" actual-data-nodes="sj_ds_${0..3}.auth_user"
database-strategy-ref="databaseStrategy"/>
</sharding:table-rules>
</sharding:sharding-rule>
<sharding:props>
<prop key="sql.show">true</prop>
<prop key="executor.size">2</prop>
</sharding:props>
</sharding:data-source>
<!-- 配置sqlSessionFactory -->
<bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean">
<!---datasource交給sharding-jdbc託管-->
<property name="dataSource" ref="shardingDataSource"/>
<property name="mapperLocations" value="classpath*:mybatis/*Mapper.xml"/>
</bean>
<bean class="org.mybatis.spring.mapper.MapperScannerConfigurer">
<property name="basePackage" value="com.crt.fin.ospsso.dal.mapper"/>
<property name="sqlSessionFactoryBeanName" value="sqlSessionFactory"/>
</bean>
</beans>
說明:spring-sharding.xml配置的分庫分表規則:auth_user表分到id為sj_ds_${0..3}的四個庫中,表名保持不變;其他表在id為sj_ds_default庫中,不分庫也不分表;整合sharding-jdbc的核心就是將SqlSessionFactoryBean需要的dataSource屬性修改為
shardingDataSource
,把資料來源交給sharding-jdbc處理;
另外,通過對比這裡和sharding-jdbc1.5.4.1版本的配置請戳連結:https://www.jianshu.com/p/602e24845ed3,差異還是比較大,大概提現在如下一些地方:
1. namespace由rdb改為sharding;
2. 預設資料庫策略和預設表策略被設定為<sharding:sharding-rule>
節點的屬性,分別是default-database-strategy-ref
和default-table-strategy-ref
;
3. 預設資料來源被設定為<sharding:sharding-rule>
節點的屬性,即default-data-source-name
;
3. <sharding:table-rule>
一些屬性變更,例如:actual-tables改為actual-data-nodes,database-strategy改為database-strategy-ref;
我們平常開發過程中,可以參考sharding-jdbc原始碼sharding-jdbc-core-spring-namespace模組中META.rdb目錄下的xml,作者對幾乎各種使用方式都有例項;
分庫邏輯AuthUserDatabaseShardingAlgorithm
的程式碼很簡單,原始碼如下:
/**
* @author wangzhenfei9
* @version 1.0.0
* @since 2018年05月14日
*/
public class AuthUserDatabaseShardingAlgorithm implements PreciseShardingAlgorithm<Long> {
private final Logger logger = LoggerFactory.getLogger(this.getClass());
private static final int SHARDING_NUMBER = 4;
@Override
public String doSharding(final Collection<String> availableTargetNames,
final PreciseShardingValue<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();
}
}
這段程式碼參考sharding-jdbc原始碼中
PreciseShardingAlgorithm.java
介面的實現即可,例如PreciseModuloDatabaseShardingAlgorithm.java
;這裡和sharding-jdbc1.5.4.1版本的差異也比較大,sharding-jdbc1.5.4.1對於分庫或者分表sharding演算法實現的介面是不一樣的,sharding-jdbc2.0.3將兩者合二為一,且只有一個方法,即doSharding();
4. 注意事項
無法識別sharding-jdbc分庫分表規則inline-expression問題,例如:
<rdb:table-rule logic-table="auth_user" actual-tables="sj_ds_${0..3}.auth_user" database-strategy="databaseStrategy"/>
根本原因:
根本原因是spring把${}
當做佔位符,${0..3}
這種表示式,spring會嘗試去properties檔案中找key為0..3
的屬性。但是這裡是sharding-jdbc分庫分表規則的inline表示式,需要spring忽略這種行為。否則會丟擲異常:
java.lang.IllegalArgumentException: Could not resolve placeholder ‘0..3’ in value “sj_ds_${0..3}.auth_user”解決辦法:
配置:<property name="ignoreUnresolvablePlaceholders" value="true"/>
或者:<context:property-placeholder ****** ignore-unresolvable="true" />
5. Main測試
Main.java用來測試分庫分表是否OK,其原始碼如下:
/**
* @author wangzhenfei9
* @version 1.0.0
* @since 2018年05月14日
*/
public class Main {
public static void main(String[] args) {
ApplicationContext context = new ClassPathXmlApplicationContext(
"/META-INF/spring/spring-*.xml");
// auth_user有進行分庫,
AuthUserMapper authUserMapper = context.getBean(AuthUserMapper.class);
AuthUser authUser = authUserMapper.selectByPrimaryKey(7L);
System.out.println("-----> The auth user: "+JSON.toJSONString(authUser));
// user_permission沒有分庫分表
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()的程式碼和沒有分庫分表的程式碼完全一樣;
6. 遺留問題
Main方法測試,或者啟動服務後的呼叫測試都沒有問題,但是通過junit測試用例訪問就會丟擲異常,作為一個待解決的遺留問題:
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