目录
一、Sharding-JDBC依赖
二、代码实践
三、源码分析
在上一篇博文中，介绍了Sharding-JDBC的分片策略、分片键和分片算法的基本概念，以及2.0.3版本可以支持和无法支持的使用场景。
可以支持的场景：支持对SQL语句中的=、IN和BETWEEN AND的分片操作，但前提是分片键必须存在于SQL和数据表结构中。
无法支持的场景：分片键不存在于SQL和数据表结构中，即基于暗示(Hint)的数据分片操作（2.0.3版本的问题）。
无可厚非，缺少了Hint分片策略的支持，Sharding-JDBC 2.0.3版本的使用场景就非常受限了，但值得庆幸的是，此问题在3.x版本进行了修复（这里可以有掌声！），接下来的代码皆基于3.1.0版本。
一、Sharding-JDBC依赖
<!-- sharding-jdbc-core --> <dependency> <groupId>io.shardingsphere</groupId> <artifactId>sharding-jdbc-core</artifactId> <version>3.1.0</version> </dependency> <!-- sharding-jdbc-spring-namespace --> <dependency> <groupId>io.shardingsphere</groupId> <artifactId>sharding-jdbc-spring-namespace</artifactId> <version>3.1.0</version> </dependency>
和2.0.3版本相比，依赖的名称有所改变，不要搞错了哦。
二、代码实践
业务背景就不再介绍了，不了解可移步至Sharding-JDBC（二）2.0.3版本实践。
如下代码配置了标准分片策略中的精确分片算法PreciseShardingAlgorithm和Hint分片算法HintShardingAlgorithm。
XML配置：
<?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:tx="http://www.springframework.org/schema/tx" xmlns:sharding="http://shardingsphere.io/schema/shardingsphere/sharding" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://shardingsphere.io/schema/shardingsphere/sharding http://shardingsphere.io/schema/shardingsphere/sharding/sharding.xsd"> <!-- 标准分片策略 --> <sharding:standard-strategy id="settlementTableShardingStandardStrategy" sharding-column="pay_serial_number" precise-algorithm-ref="preciseTableShardingAlgorithm"/> <!-- 基于暗示(Hint)的分片策略 --> <sharding:hint-strategy id="settlementHintTableShardingStrategy" algorithm-ref="hintTableShardingAlgorithm"/> <sharding:hint-strategy id="settlementHintDatabaseShardingStrategy" algorithm-ref="hintDatabaseShardingAlgorithm"/> <sharding:data-source id="shardingDataSource"> <sharding:sharding-rule data-source-names="dataSource"> <sharding:table-rules> <sharding:table-rule logic-table="settlement" table-strategy-ref="settlementTableShardingStandardStrategy"/> <!-- logic-table参数的大小写必须和SettlementMapper.xml中selectByExample方法的表名大小一致！！！ --> <!-- logic-table必须和org.cellphone.finance.repo.SettlementRepository.querySettlements中的logicTable及SQL中的表名一致，否则无法找到分片策略 --> <!-- 逻辑表名，不需要和真实表名一致 --> <sharding:table-rule logic-table="settlement_hint" database-strategy-ref="settlementHintDatabaseShardingStrategy" table-strategy-ref="settlementHintTableShardingStrategy"/> </sharding:table-rules> </sharding:sharding-rule> <sharding:props> <prop key="sql.show">true</prop> </sharding:props> </sharding:data-source> <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> <property name="dataSource" ref="shardingDataSource"/> </bean> <tx:annotation-driven/> </beans>
精确分片算法：
package org.cellphone.finance.repo.sharding; import com.google.common.collect.Lists; import io.shardingsphere.api.algorithm.sharding.PreciseShardingValue; import io.shardingsphere.api.algorithm.sharding.standard.PreciseShardingAlgorithm; import org.apache.commons.collections.CollectionUtils; import org.cellphone.common.constant.CommonConst; import org.springframework.stereotype.Component; import java.util.Collection; /** * 精确分片算法，属于标准分片算法，用于处理=和IN的分片 * <p> * 使用精确分片算法的前提：分片字段必须存在与SQL中、数据库表结构中，否则无法使用精确分片算法 * <p> * 此分片算法应用于SETTLEMENT数据表，这里是按天分表 * <p> * 特别说明：Sharding Jdbc版本：3.1.0 * <p> * Created by on 2018/4/9. */ @Component("preciseTableShardingAlgorithm") public class PreciseTableShardingAlgorithm implements PreciseShardingAlgorithm<String> { /** * 精确分片算法 * * @param availableTargetNames 目标数据源名称或数据表名称，注意：是逻辑数据源名或逻辑数据表名，来自SQL * @param shardingValue 分片值，来自SQL中分片字段对应的值 * @return 真实数据源名称或数据表名称 */ @Override public String doSharding(final Collection<String> availableTargetNames, final PreciseShardingValue<String> shardingValue) { // 默认数据表名称，有可能数据库中不存在这张表 String tableName = "settlement"; // 逻辑表名为空，返回默认表名 if (CollectionUtils.isEmpty(availableTargetNames)) return tableName; // availableTargetNames来自SQL，只有一个元素 tableName = Lists.newArrayList(availableTargetNames).get(0); String paySerialNumber = shardingValue.getValue(); String suffix = paySerialNumber.substring(5, 13); return tableName + CommonConst.UNDERLINE + suffix; } }
Hint数据源分片算法：
package org.cellphone.finance.repo.sharding; import io.shardingsphere.api.algorithm.sharding.ShardingValue; import io.shardingsphere.api.algorithm.sharding.hint.HintShardingAlgorithm; import org.springframework.stereotype.Component; import java.util.Collection; /** * Sharding Jdbc基于暗示(Hint)的数据分片算法 * * 使用Sharding Jdbc 3.x版本时，此数据源分片算法这个一定要有！！！ * 否则无法正常使用org.cellphone.finance.repo.sharding.HintTableShardingAlgorithm算法 * <p> * Created by on 2019/4/25. */ @Component("hintDatabaseShardingAlgorithm") public class HintDatabaseShardingAlgorithm implements HintShardingAlgorithm { @Override public Collection<String> doSharding(Collection<String> availableTargetNames, ShardingValue shardingValue) { return availableTargetNames; } }
Hint数据表分片算法：
package org.cellphone.finance.repo.sharding; import com.google.common.collect.Lists; import io.shardingsphere.api.algorithm.sharding.ListShardingValue; import io.shardingsphere.api.algorithm.sharding.ShardingValue; import io.shardingsphere.api.algorithm.sharding.hint.HintShardingAlgorithm; import org.apache.commons.collections.CollectionUtils; import org.apache.commons.lang3.StringUtils; import org.apache.commons.lang3.time.DateFormatUtils; import org.apache.commons.lang3.time.DateUtils; import org.cellphone.common.constant.CommonConst; import org.cellphone.common.constant.DateConst; import org.springframework.stereotype.Component; import java.text.ParseException; import java.util.*; /** * Sharding Jdbc基于暗示(Hint)的数据分片算法 * 版本：Sharding Jdbc 3.1.0 * * 官方介绍（2.x版本）：http://shardingsphere.apache.org/document/legacy/2.x/cn/02-guide/hint-sharding-value/ * 官方介绍（4.x版本）：https://shardingsphere.apache.org/document/current/cn/manual/sharding-jdbc/usage/hint/ * <p> * <p> * <p> * <p> * 使用此算法的背景如下： * 1. SETTLEMENT（支付表）是按时间维度进行分表，该时间取自PAY_SERIAL_NUMBER中的时间数据，非表中的时间字段； * <p> * 2. 使用用户手机号此类条件查询数据时，请求参数除传入业务参数外， * 还需传入时间段（即分片字段，例：startTime和endTime）以确定分表范围； * 但是！！！startTime和endTime（即分片字段）不存在SQL中、数据库表结构中，而存在于外部业务逻辑 * <p> * <p> * <p> * 因此，第2点导致无法直接使用Sharding Jdbc的PreciseShardingAlgorithm（精确分片算法）或RangeShardingAlgorithm（范围分片算法）， * 只能使用HintShardingAlgorithm（基于暗示的数据分片算法），该算法的使用场景如下： * 1. 分片字段不存在SQL中、数据库表结构中，而存在于外部业务逻辑； * <p> * 2. 强制在主库进行某些数据操作。 * <p> * <p> * Created by on 2019/4/25. */ @Component("hintTableShardingAlgorithm") public class HintTableShardingAlgorithm implements HintShardingAlgorithm { /** * 分片算法 * * @param availableTargetNames 逻辑数据库名称或逻辑数据表名称 * @param shardingValue 用来确定分表的参数 * @return 实际数据表名称列表，SQL实际操作的数据表 */ @Override public Collection<String> doSharding(Collection<String> availableTargetNames, ShardingValue shardingValue) { String realTableName = StringUtils.EMPTY; for (String each : availableTargetNames) { if (StringUtils.isNotBlank(each)) { // 基于hint的逻辑表名：settlement_hint realTableName = each.replace("_hint", StringUtils.EMPTY); break; } } List<String> tables = new ArrayList<>(); ListShardingValue<String> listShardingValue = (ListShardingValue<String>) shardingValue; List<String> list = Lists.newArrayList(listShardingValue.getValues()); // 缺少确定分表的参数，无法确定具体分表，直接返回真实表名称 if (CollectionUtils.isEmpty(list)) { tables.add(realTableName); return tables; } // 拆分分表参数，此参数值来自：com.fcbox.manage.core.repo.FcBoxPostRepository.queryFcBoxPosts() String[] queryTime = list.get(0).split(CommonConst.UNDERLINE); Date startTime, endTime; try { startTime = DateUtils.parseDate(queryTime[0], DateConst.DATE_FORMAT_NORMAL); endTime = DateUtils.parseDate(queryTime[1], DateConst.DATE_FORMAT_NORMAL); } catch (ParseException e) { // 分表参数解析错误，无法确定具体分表，直接返回真实表名称 tables.add(realTableName); return tables; } Calendar calendar = Calendar.getInstance(); // 组织startTime和endTime时段范围内的分表 while (startTime.getTime() <= endTime.getTime()) { tables.add(realTableName + CommonConst.UNDERLINE + DateFormatUtils.format(startTime, DateConst.DATE_FORMAT_YYYY_MM_DD)); calendar.setTime(startTime); calendar.add(Calendar.DATE, 1); startTime = calendar.getTime(); } return tables; } }
与Hint分片算法对应的Java查询方法 settlementMapper.selectByExample(example)：
public List<Settlement> querySettlements(SettlementExample example, String startTime, String endTime) { // 组织查询时间，传入org.cellphone.finance.repo.sharding.HintTableShardingAlgorithm分片算法中以确认具体分表 String queryTime = startTime + CommonConst.UNDERLINE + endTime; // 获取HintManager HintManager hintManager = HintManager.getInstance(); /* * 添加数据源分片键值，使用Sharding Jdbc 3.x版本一定要添加数据源分片键值，否则无法使用HintTableShardingAlgorithm分片算法 * 若无分库，addDatabaseShardingValue方法的value字段随意填充 * 若有分库，addDatabaseShardingValue方法的value字段填充实际参数值 */ hintManager.addDatabaseShardingValue("settlement_hint", StringUtils.EMPTY); // 添加数据表分片键值 hintManager.addTableShardingValue("settlement_hint", queryTime); List<Settlement> settlements = settlementMapper.selectByExample(example); // 清除分片键值 hintManager.close(); return settlements; }
以及该查询方法对应的SQL语句：
select * from settlement_hint t where t.pay_serial_number = ?
单元测试代码：
@Test public void test003QuerySettlements() throws ParseException { String startTime = "2018-04-03 00:00:00", endTime = "2018-04-05 00:00:00"; SettlementExample example = new SettlementExample(); SettlementExample.Criteria criteria = example.createCriteria(); criteria.andPaySerialNumberEqualTo(paySerialNumber); List<Settlement> settlements = repository.querySettlements(example, startTime, endTime); Assert.assertEquals("136********", settlements.get(0).getUserMobile()); }
三、源码分析
和2.0.3版本相比，3.1.0版本的路由入口变成了 io.shardingsphere.core.routing.type.standard.StandardRoutingEngine#route() ，但基本上区别不大，仅仅是多了一步需要确定路由的真实数据源，尽管数据源只有一个，也需要显式配置数据源路由算法。代码中标注了注释的部分都是路由代码比较核心的部分。
/* * Copyright 2016-2018 shardingsphere.io. * <p> * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * </p> */ package io.shardingsphere.core.routing.type.standard; import com.google.common.base.Optional; import com.google.common.base.Preconditions; import io.shardingsphere.api.algorithm.sharding.ShardingValue; import io.shardingsphere.core.hint.HintManagerHolder; import io.shardingsphere.core.optimizer.condition.ShardingCondition; import io.shardingsphere.core.optimizer.condition.ShardingConditions; import io.shardingsphere.core.optimizer.insert.InsertShardingCondition; import io.shardingsphere.core.routing.strategy.ShardingStrategy; import io.shardingsphere.core.routing.strategy.hint.HintShardingStrategy; import io.shardingsphere.core.routing.type.RoutingEngine; import io.shardingsphere.core.routing.type.RoutingResult; import io.shardingsphere.core.routing.type.RoutingTable; import io.shardingsphere.core.routing.type.TableUnit; import io.shardingsphere.core.rule.BindingTableRule; import io.shardingsphere.core.rule.DataNode; import io.shardingsphere.core.rule.ShardingRule; import io.shardingsphere.core.rule.TableRule; import lombok.RequiredArgsConstructor; import java.util.ArrayList; import java.util.Collection; import java.util.Collections; import java.util.LinkedHashSet; import java.util.LinkedList; import java.util.List; /** * Standard routing engine. * * @author zhangliang * @author maxiaoguang * @author panjuan */ @RequiredArgsConstructor public final class StandardRoutingEngine implements RoutingEngine { private final ShardingRule shardingRule; private final String logicTableName; private final ShardingConditions shardingConditions; /** * 相比2.0.3版本，精简成了1行代码 * * @return 路由结果 */ @Override public RoutingResult route() { return generateRoutingResult(getDataNodes(shardingRule.getTableRuleByLogicTableName(logicTableName))); } private RoutingResult generateRoutingResult(final Collection<DataNode> routedDataNodes) { RoutingResult result = new RoutingResult(); for (DataNode each : routedDataNodes) { TableUnit tableUnit = new TableUnit(each.getDataSourceName()); tableUnit.getRoutingTables().add(new RoutingTable(logicTableName, each.getTableName())); result.getTableUnits().getTableUnits().add(tableUnit); } return result; } /** * 获取数据节点，即真实表 * * @param tableRule 从XML读取的table rule * @return 数据节点列表 */ private Collection<DataNode> getDataNodes(final TableRule tableRule) { // 判断是否是通过Hint分片策略进行路由 if (isRoutingByHint(tableRule)) { return routeByHint(tableRule); } if (isRoutingByShardingConditions(tableRule)) { return routeByShardingConditions(tableRule); } return routeByMixedConditions(tableRule); } /** * 判断是否是通过Hint分片策略进行路由 * <p> * 数据源分片策略和数据表分片策略都必须是HintShardingStrategy，这意味者必须显式配置数据源Hint分片策略和数据表Hint分片策略 * * @param tableRule 从XML读取的table rule * @return */ private boolean isRoutingByHint(final TableRule tableRule) { return shardingRule.getDatabaseShardingStrategy(tableRule) instanceof HintShardingStrategy && shardingRule.getTableShardingStrategy(tableRule) instanceof HintShardingStrategy; } /** * 通过Hint分片策略进行路由 * * @param tableRule * @return */ private Collection<DataNode> routeByHint(final TableRule tableRule) { return route(tableRule, getDatabaseShardingValuesFromHint(), getTableShardingValuesFromHint()); } private boolean isRoutingByShardingConditions(final TableRule tableRule) { return !(shardingRule.getDatabaseShardingStrategy(tableRule) instanceof HintShardingStrategy || shardingRule.getTableShardingStrategy(tableRule) instanceof HintShardingStrategy); } private Collection<DataNode> routeByShardingConditions(final TableRule tableRule) { return shardingConditions.getShardingConditions().isEmpty() ? route(tableRule, Collections.<ShardingValue>emptyList(), Collections.<ShardingValue>emptyList()) : routeByShardingConditionsWithCondition(tableRule); } private Collection<DataNode> routeByShardingConditionsWithCondition(final TableRule tableRule) { Collection<DataNode> result = new LinkedList<>(); for (ShardingCondition each : shardingConditions.getShardingConditions()) { Collection<DataNode> dataNodes = route(tableRule, getShardingValuesFromShardingConditions(shardingRule.getDatabaseShardingStrategy(tableRule).getShardingColumns(), each), getShardingValuesFromShardingConditions(shardingRule.getTableShardingStrategy(tableRule).getShardingColumns(), each)); reviseShardingConditions(each, dataNodes); result.addAll(dataNodes); } return result; } private Collection<DataNode> routeByMixedConditions(final TableRule tableRule) { return shardingConditions.getShardingConditions().isEmpty() ? routeByMixedConditionsWithHint(tableRule) : routeByMixedConditionsWithCondition(tableRule); } private Collection<DataNode> routeByMixedConditionsWithCondition(final TableRule tableRule) { Collection<DataNode> result = new LinkedList<>(); for (ShardingCondition each : shardingConditions.getShardingConditions()) { Collection<DataNode> dataNodes = route(tableRule, getDatabaseShardingValues(tableRule, each), getTableShardingValues(tableRule, each)); reviseShardingConditions(each, dataNodes); result.addAll(dataNodes); } return result; } private Collection<DataNode> routeByMixedConditionsWithHint(final TableRule tableRule) { if (shardingRule.getDatabaseShardingStrategy(tableRule) instanceof HintShardingStrategy) { return route(tableRule, getDatabaseShardingValuesFromHint(), Collections.<ShardingValue>emptyList()); } return route(tableRule, Collections.<ShardingValue>emptyList(), getTableShardingValuesFromHint()); } private List<ShardingValue> getDatabaseShardingValues(final TableRule tableRule, final ShardingCondition shardingCondition) { ShardingStrategy dataBaseShardingStrategy = shardingRule.getDatabaseShardingStrategy(tableRule); return isGettingShardingValuesFromHint(dataBaseShardingStrategy) ? getDatabaseShardingValuesFromHint() : getShardingValuesFromShardingConditions(dataBaseShardingStrategy.getShardingColumns(), shardingCondition); } private List<ShardingValue> getTableShardingValues(final TableRule tableRule, final ShardingCondition shardingCondition) { ShardingStrategy tableShardingStrategy = shardingRule.getTableShardingStrategy(tableRule); return isGettingShardingValuesFromHint(tableShardingStrategy) ? getTableShardingValuesFromHint() : getShardingValuesFromShardingConditions(tableShardingStrategy.getShardingColumns(), shardingCondition); } private boolean isGettingShardingValuesFromHint(final ShardingStrategy shardingStrategy) { return shardingStrategy instanceof HintShardingStrategy; } /** * 从HintManagerHolder中获取数据源分片值 * * @return 数据源分片值列表 */ private List<ShardingValue> getDatabaseShardingValuesFromHint() { // getDatabaseShardingValue方法实现有点恶心，不兼容大小写... Optional<ShardingValue> shardingValueOptional = HintManagerHolder.getDatabaseShardingValue(logicTableName); return shardingValueOptional.isPresent() ? Collections.singletonList(shardingValueOptional.get()) : Collections.<ShardingValue>emptyList(); } private List<ShardingValue> getTableShardingValuesFromHint() { // getTableShardingValue方法实现有点恶心，不兼容大小写... Optional<ShardingValue> shardingValueOptional = HintManagerHolder.getTableShardingValue(logicTableName); return shardingValueOptional.isPresent() ? Collections.singletonList(shardingValueOptional.get()) : Collections.<ShardingValue>emptyList(); } private List<ShardingValue> getShardingValuesFromShardingConditions(final Collection<String> shardingColumns, final ShardingCondition shardingCondition) { List<ShardingValue> result = new ArrayList<>(shardingColumns.size()); for (ShardingValue each : shardingCondition.getShardingValues()) { Optional<BindingTableRule> bindingTableRule = shardingRule.findBindingTableRule(logicTableName); if ((logicTableName.equals(each.getLogicTableName()) || bindingTableRule.isPresent() && bindingTableRule.get().hasLogicTable(logicTableName)) && shardingColumns.contains(each.getColumnName())) { result.add(each); } } return result; } /** * 路由，获取真实表列表 * * @param tableRule 从XML读取的table rule * @param databaseShardingValues 数据源分片值 * @param tableShardingValues 数据表分片值 * @return 真实表列表 */ private Collection<DataNode> route(final TableRule tableRule, final List<ShardingValue> databaseShardingValues, final List<ShardingValue> tableShardingValues) { Collection<String> routedDataSources = routeDataSources(tableRule, databaseShardingValues); Collection<DataNode> result = new LinkedList<>(); for (String each : routedDataSources) { result.addAll(routeTables(tableRule, each, tableShardingValues)); } return result; } /** * 路由到真实数据源 * * @param tableRule 从XML读取的table rule * @param databaseShardingValues 数据源分片值 * @return 真实数据源列表 */ private Collection<String> routeDataSources(final TableRule tableRule, final List<ShardingValue> databaseShardingValues) { Collection<String> availableTargetDatabases = tableRule.getActualDatasourceNames(); if (databaseShardingValues.isEmpty()) { return availableTargetDatabases; } Collection<String> result = new LinkedHashSet<>(shardingRule.getDatabaseShardingStrategy(tableRule).doSharding(availableTargetDatabases, databaseShardingValues)); Preconditions.checkState(!result.isEmpty(), "no database route info"); return result; } /** * 路由到真实数据表，和2.0.3版本没啥区别 * * @param tableRule 从XML读取的table rule * @param routedDataSource 已确认好的数据源 * @param tableShardingValues 数据表分片值 * @return 真实表列表 */ private Collection<DataNode> routeTables(final TableRule tableRule, final String routedDataSource, final List<ShardingValue> tableShardingValues) { Collection<String> availableTargetTables = tableRule.getActualTableNames(routedDataSource); Collection<String> routedTables = new LinkedHashSet<>(tableShardingValues.isEmpty() ? availableTargetTables : shardingRule.getTableShardingStrategy(tableRule).doSharding(availableTargetTables, tableShardingValues)); Preconditions.checkState(!routedTables.isEmpty(), "no table route info"); Collection<DataNode> result = new LinkedList<>(); for (String each : routedTables) { result.add(new DataNode(routedDataSource, each)); } return result; } private void reviseShardingConditions(final ShardingCondition each, final Collection<DataNode> dataNodes) { if (each instanceof InsertShardingCondition) { ((InsertShardingCondition) each).getDataNodes().addAll(dataNodes); } } }
分析到此，Sharding-JDBC 3.1.0版本可以支持分片键不存在于SQL中和数据表结构中的使用场景。但3.1.0版本还有一个比较恶心的地方，Sharding-JDBC在初始化时，会连接数据库获取数据表的元数据，包括需要水平切分的表和不需水平切分的表。代码如下：
/* * Copyright 2016-2018 shardingsphere.io. * <p> * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * </p> */ package io.shardingsphere.core.metadata.table.executor; import com.google.common.base.Optional; import io.shardingsphere.core.exception.ShardingException; import io.shardingsphere.core.executor.ShardingExecuteEngine; import io.shardingsphere.core.metadata.datasource.DataSourceMetaData; import io.shardingsphere.core.metadata.datasource.ShardingDataSourceMetaData; import io.shardingsphere.core.metadata.table.TableMetaData; import io.shardingsphere.core.rule.ShardingRule; import io.shardingsphere.core.rule.TableRule; import java.sql.Connection; import java.sql.ResultSet; import java.sql.SQLException; import java.util.Collection; import java.util.HashMap; import java.util.LinkedHashSet; import java.util.Map; /** * Table meta data initializer. * * @author zhangliang */ public final class TableMetaDataInitializer { private final ShardingDataSourceMetaData shardingDataSourceMetaData; private final TableMetaDataConnectionManager connectionManager; private final TableMetaDataLoader tableMetaDataLoader; public TableMetaDataInitializer(final ShardingDataSourceMetaData shardingDataSourceMetaData, final ShardingExecuteEngine executeEngine, final TableMetaDataConnectionManager connectionManager, final int maxConnectionsSizePerQuery, final boolean isCheckingMetaData) { this.shardingDataSourceMetaData = shardingDataSourceMetaData; this.connectionManager = connectionManager; tableMetaDataLoader = new TableMetaDataLoader(shardingDataSourceMetaData, executeEngine, connectionManager, maxConnectionsSizePerQuery, isCheckingMetaData); } /** * Load all table meta data. * * @param shardingRule sharding rule * @return all table meta data */ public Map<String, TableMetaData> load(final ShardingRule shardingRule) { Map<String, TableMetaData> result = new HashMap<>(); try { // 加载需要水平切分的表元数据 result.putAll(loadShardingTables(shardingRule)); // 加载不需水平切分的表元数据，如果数据库中表数量很大，这里耗时很久... result.putAll(loadDefaultTables(shardingRule)); } catch (final SQLException ex) { throw new ShardingException(ex); } return result; } private Map<String, TableMetaData> loadShardingTables(final ShardingRule shardingRule) throws SQLException { Map<String, TableMetaData> result = new HashMap<>(shardingRule.getTableRules().size(), 1); for (TableRule each : shardingRule.getTableRules()) { result.put(each.getLogicTable(), tableMetaDataLoader.load(each.getLogicTable(), shardingRule)); } return result; } private Map<String, TableMetaData> loadDefaultTables(final ShardingRule shardingRule) throws SQLException { Map<String, TableMetaData> result = new HashMap<>(shardingRule.getTableRules().size(), 1); Optional<String> actualDefaultDataSourceName = shardingRule.findActualDefaultDataSourceName(); if (actualDefaultDataSourceName.isPresent()) { for (String each : getAllTableNames(actualDefaultDataSourceName.get())) { result.put(each, tableMetaDataLoader.load(each, shardingRule)); } } return result; } /** * 连接数据库，获取所有表元数据 * * @param dataSourceName 数据源名称 * @return 所有数据表元数据列表 * @throws SQLException */ private Collection<String> getAllTableNames(final String dataSourceName) throws SQLException { Collection<String> result = new LinkedHashSet<>(); DataSourceMetaData dataSourceMetaData = shardingDataSourceMetaData.getActualDataSourceMetaData(dataSourceName); String catalog = null == dataSourceMetaData ? null : dataSourceMetaData.getSchemeName(); try (Connection connection = connectionManager.getConnection(dataSourceName); ResultSet resultSet = connection.getMetaData().getTables(catalog, null, null, new String[]{"TABLE"})) { while (resultSet.next()) { String tableName = resultSet.getString("TABLE_NAME"); if (!tableName.contains("$")) { result.add(tableName); } } } return result; } }