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一 什么是 ShardingSphere？

1.1 背景：为什么需要分库分表？

随着系统数据量和用户量不断增长，传统单体数据库容易遇到瓶颈：

• 写入/查询压力大：单表千万级数据，索引效率下降。

• 存储超限：单机磁盘空间和 IOPS 不堪重负。

• 水平扩展困难：业务难以横向拓展。

为了解决这些问题，开发者往往采用 分库分表 技术，将一张大表分成多个小表，分布在不同数据库中，实现水平扩展和负载均衡。

1.2 什么是 Apache ShardingSphere？

Apache ShardingSphere 是一款开源的 分布式数据库中间件框架，可以帮助开发者轻松实现：

• 分库分表

• 读写分离

• 分布式事务

• 数据脱敏

• 可观测性 & 扩展治理能力

ShardingSphere 核心组件包括：

组件	说明
ShardingSphere-JDBC	JDBC 封装层，嵌入应用中，适用于微服务架构
ShardingSphere-Proxy	独立部署的数据库代理，支持多语言访问
ShardingSphere-Sidecar（规划中）	面向云原生场景，Service Mesh 结构

1.3 ShardingSphere-JDBC 的核心功能

功能	简要说明
分库分表	按字段配置路由策略，自动将 SQL 分发到对应的数据库/表
读写分离	自动区分读写请求，路由到主/从数据库
灵活分片策略	支持取模、范围、Hint、自定义算法等多种策略
事务支持	支持本地事务和分布式事务（Seata/XA）
透明化使用	对开发者来说使用方式与普通 JDBC 几乎一致，只需配置逻辑表名

二、实践部分：Java + H2 实现分库分表

示例：使用 Java 原生程序 + ShardingSphere-JDBC + H2 内存数据库，模拟一个电商订单系统按 user_id 分库，order_id 分表。

2.1 项目结构

• 使用 H2 数据库模拟两个库 ds0, ds1

• 每个库中创建两个分表 t_order_0, t_order_1

• 逻辑表名：t_order

2.2 Maven 依赖配置

<dependencies><dependency><groupId>org.apache.shardingsphere</groupId><artifactId>shardingsphere-jdbc-core</artifactId><version>5.4.1</version></dependency><dependency><groupId>com.h2database</groupId><artifactId>h2</artifactId><version>2.2.220</version></dependency><dependency><groupId>com.zaxxer</groupId><artifactId>HikariCP</artifactId><version>5.0.1</version></dependency>
</dependencies>

2.3 核心代码结构

1. 创建真实表（物理分表）

public static void createTables() throws SQLException {for (int i = 0; i < 2; i++) {String db = "ds" + i;try (Connection conn = DriverManager.getConnection("jdbc:h2:mem:" + db + ";DB_CLOSE_DELAY=-1;MODE=MySQL", "sa", "")) {Statement stmt = conn.createStatement();for (int j = 0; j < 2; j++) {stmt.execute(String.format("""CREATE TABLE IF NOT EXISTS t_order_%d (order_id BIGINT PRIMARY KEY,user_id INT,status VARCHAR(50))""", j));}}}
}

2. 配置分库分表数据源

public static DataSource createDataSource() throws SQLException {Map<String, DataSource> dataSourceMap = new HashMap<>();for (int i = 0; i < 2; i++) {HikariDataSource ds = new HikariDataSource();ds.setJdbcUrl("jdbc:h2:mem:ds" + i + ";DB_CLOSE_DELAY=-1;MODE=MySQL");ds.setUsername("sa");ds.setPassword("");dataSourceMap.put("ds" + i, ds);}ShardingTableRuleConfiguration orderTableRule = new ShardingTableRuleConfiguration("t_order", "ds${0..1}.t_order_${0..1}");orderTableRule.setDatabaseShardingStrategy(new StandardShardingStrategyConfiguration("user_id", "dbSharding"));orderTableRule.setTableShardingStrategy(new StandardShardingStrategyConfiguration("order_id", "tableSharding"));ShardingRuleConfiguration config = new ShardingRuleConfiguration();config.getTables().add(orderTableRule);config.getShardingAlgorithms().put("dbSharding",new AlgorithmConfiguration("INLINE", props("algorithm-expression", "ds${user_id % 2}")));config.getShardingAlgorithms().put("tableSharding",new AlgorithmConfiguration("INLINE", props("algorithm-expression", "t_order_${order_id % 2}")));return ShardingSphereDataSourceFactory.createDataSource(dataSourceMap, List.of(config), new Properties());
}

3. 插入与查询数据

public static void insertOrder(DataSource ds, long orderId, int userId, String status) throws SQLException {try (Connection conn = ds.getConnection()) {PreparedStatement ps = conn.prepareStatement("INSERT INTO t_order (order_id, user_id, status) VALUES (?, ?, ?)");ps.setLong(1, orderId);ps.setInt(2, userId);ps.setString(3, status);ps.executeUpdate();}
}public static void queryOrders(DataSource ds) throws SQLException {try (Connection conn = ds.getConnection()) {ResultSet rs = conn.createStatement().executeQuery("SELECT * FROM t_order");while (rs.next()) {System.out.printf("order_id=%d, user_id=%d, status=%s%n",rs.getLong("order_id"),rs.getInt("user_id"),rs.getString("status"));}}
}

2.4 程序入口

public static void main(String[] args) throws Exception {createTables();  // 创建实际分表DataSource shardingDataSource = createDataSource();insertOrder(shardingDataSource, 1001, 1, "INIT");insertOrder(shardingDataSource, 1002, 2, "PAID");insertOrder(shardingDataSource, 1003, 3, "SHIPPED");queryOrders(shardingDataSource);
}

 输出示例

order_id=1001, user_id=1, status=INIT
order_id=1002, user_id=2, status=PAID
order_id=1003, user_id=3, status=SHIPPED

ShardingSphere 已自动根据你配置的策略将数据路由到对应的库和表！

总结

Apache ShardingSphere 提供了强大、灵活的分库分表能力，通过合理配置可以极大提升系统的性能与扩展性：

• 分片策略灵活，支持多种规则或自定义算法

• 配置简单，无需改动业务 SQL

• 兼容性强，支持 JDBC、Spring Boot、YAML 等多种使用方式

无论你是中小项目的快速原型，还是大规模高并发系统，ShardingSphere 都是一个值得一试的解决方案。

完整代码

package org.example;import com.zaxxer.hikari.HikariDataSource;
import org.apache.shardingsphere.driver.api.ShardingSphereDataSourceFactory;import org.apache.shardingsphere.infra.config.algorithm.AlgorithmConfiguration;
import org.apache.shardingsphere.sharding.api.config.ShardingRuleConfiguration;
import org.apache.shardingsphere.sharding.api.config.rule.ShardingTableRuleConfiguration;
import org.apache.shardingsphere.sharding.api.config.strategy.sharding.StandardShardingStrategyConfiguration;import javax.sql.DataSource;
import java.sql.*;
import java.util.*;public class ShardingH2Example {public static void main(String[] args) throws Exception {createTables(); //  注意：用 DriverManager 直连底层 db 建表DataSource shardingDataSource = createDataSource();// 插入测试数据insertOrder(shardingDataSource, 1001, 1, "INIT");insertOrder(shardingDataSource, 1002, 2, "PAID");insertOrder(shardingDataSource, 1003, 3, "SHIPPED");// 查询测试数据queryOrders(shardingDataSource);}public static DataSource createDataSource() throws Exception {Map<String, DataSource> dataSourceMap = new HashMap<>();// 模拟两个库：ds0 和 ds1（分别用两个内存 H2 实例模拟）for (int i = 0; i < 2; i++) {HikariDataSource ds = new HikariDataSource();ds.setJdbcUrl("jdbc:h2:mem:ds" + i + ";DB_CLOSE_DELAY=-1;MODE=MySQL");ds.setUsername("sa");ds.setPassword("");dataSourceMap.put("ds" + i, ds);}// 分表规则配置ShardingTableRuleConfiguration orderTableRule = new ShardingTableRuleConfiguration("t_order", "ds${0..1}.t_order_${0..1}");// 分库策略（user_id）orderTableRule.setDatabaseShardingStrategy(new StandardShardingStrategyConfiguration("user_id", "dbSharding"));// 分表策略（order_id）orderTableRule.setTableShardingStrategy(new StandardShardingStrategyConfiguration("order_id", "tableSharding"));ShardingRuleConfiguration shardingRuleConfig = new ShardingRuleConfiguration();shardingRuleConfig.getTables().add(orderTableRule);Properties dbProps = new Properties();dbProps.setProperty("algorithm-expression", "ds${user_id % 2}");shardingRuleConfig.getShardingAlgorithms().put("dbSharding",new AlgorithmConfiguration("INLINE", dbProps));Properties tableProps = new Properties();tableProps.setProperty("algorithm-expression", "t_order_${order_id % 2}");shardingRuleConfig.getShardingAlgorithms().put("tableSharding",new AlgorithmConfiguration("INLINE", tableProps));return ShardingSphereDataSourceFactory.createDataSource(dataSourceMap, List.of(shardingRuleConfig), new Properties());}public static void createTables() throws SQLException {for (int i = 0; i < 2; i++) {String dbName = "ds" + i;try (Connection conn = DriverManager.getConnection("jdbc:h2:mem:" + dbName + ";DB_CLOSE_DELAY=-1;MODE=MySQL", "sa", "")) {Statement stmt = conn.createStatement();for (int j = 0; j < 2; j++) {String sql = String.format("""CREATE TABLE IF NOT EXISTS t_order_%d (order_id BIGINT PRIMARY KEY,user_id INT,status VARCHAR(50))""", j);stmt.execute(sql);}}}}// 辅助方法用于手动连接底层 H2 数据源private static HikariDataSource getH2DataSource(String name) {HikariDataSource ds = new HikariDataSource();ds.setJdbcUrl("jdbc:h2:mem:" + name + ";DB_CLOSE_DELAY=-1;MODE=MySQL");ds.setUsername("sa");ds.setPassword("");return ds;}public static void insertOrder(DataSource ds, long orderId, int userId, String status) throws SQLException {try (Connection conn = ds.getConnection()) {PreparedStatement ps = conn.prepareStatement("INSERT INTO t_order (order_id, user_id, status) VALUES (?, ?, ?)");ps.setLong(1, orderId);ps.setInt(2, userId);ps.setString(3, status);ps.executeUpdate();}}public static void queryOrders(DataSource ds) throws SQLException {try (Connection conn = ds.getConnection()) {ResultSet rs = conn.createStatement().executeQuery("SELECT * FROM t_order");System.out.println("Query Results:");while (rs.next()) {System.out.printf("order_id: %d, user_id: %d, status: %s%n",rs.getLong("order_id"),rs.getInt("user_id"),rs.getString("status"));}}}
}