2.【Sharding-JDBC】快速入门

2.Sharding-JDBC快速入门

2.1 需求说明

本章节使用Sharding-JDBC完成对订单表的水平分表，通过快速入门程序的开发，快速体验Sharding-JDBC的使用方法。

人工创建两张表，t_order_1和t_order_2，这两张表是订单表拆分后的表，通过Sharding-Jdbc向订单表插入数据，按照一定的分片规则，主键为偶数的进入t_order_1，另一部分数据进入t_order_2，通过Sharding-Jdbc 查询数据，根据 SQL语句的内容从t_order_1或t_order_2查询数据。

2.2.环境搭建

2.2.1 环境说明

• 操作系统：Win10
• 数据库：MySQL-5.7.25
• JDK：64位 jdk1.8.0_201
• 应用框架：spring-boot-2.1.3.RELEASE，Mybatis3.5.0
• Sharding-JDBC：sharding-jdbc-spring-boot-starter-4.0.0-RC1

2.2.2 创建数据库

创建订单库order_db

CREATE DATABASE `order_db` CHARACTER SET 'utf8' COLLATE 'utf8_general_ci';

在order_db中创建t_order_1、t_order_2表

DROP TABLE IF EXISTS `t_order_1`;
CREATE TABLE `t_order_1` (
	`order_id` bigint(20) NOT NULL COMMENT '订单id',
	`price` decimal(10, 2) NOT NULL COMMENT '订单价格',
	`user_id` bigint(20) NOT NULL COMMENT '下单用户id',
	`status` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '订单状态',
	PRIMARY KEY (`order_id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

DROP TABLE IF EXISTS `t_order_2`;
CREATE TABLE `t_order_2` (
	`order_id` bigint(20) NOT NULL COMMENT '订单id',
	`price` decimal(10, 2) NOT NULL COMMENT '订单价格',
	`user_id` bigint(20) NOT NULL COMMENT '下单用户id',
	`status` varchar(50) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL COMMENT '订单状态',
	PRIMARY KEY (`order_id`) USING BTREE
) ENGINE = InnoDB CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Dynamic;

2.2.3.引入maven依赖

引入 sharding-jdbc和SpringBoot整合的Jar包：

<dependency>
	<groupId>org.apache.shardingspheregroupId>
	<artifactId>sharding‐jdbc‐spring‐boot‐starterartifactId>
	<version>4.0.0‐RC1version>
dependency>

具体spring boot相关依赖及配置请参考资料中dbsharding/sharding-jdbc-simple工程，本指引只说明与ShardingJDBC相关的内容。

2.3 编写程序

2.3.1 分片规则配置

分片规则配置是sharding-jdbc进行对分库分表操作的重要依据，配置内容包括：数据源、主键生成策略、分片策略等。

在application.properties中配置

server.port=56081

spring.application.name = sharding‐jdbc‐simple‐demo
server.servlet.context‐path = /sharding‐jdbc‐simple‐demo
spring.http.encoding.enabled = true
spring.http.encoding.charset = UTF‐8
spring.http.encoding.force = true

spring.main.allow‐bean‐definition‐overriding = true

mybatis.configuration.map‐underscore‐to‐camel‐case = true

# 以下是分片规则配置
# 定义数据源
spring.shardingsphere.datasource.names = m1
spring.shardingsphere.datasource.m1.type = com.alibaba.druid.pool.DruidDataSource
spring.shardingsphere.datasource.m1.driver‐class‐name = com.mysql.jdbc.Driver
spring.shardingsphere.datasource.m1.url = jdbc:mysql://localhost:3306/order_db?useUnicode=true
spring.shardingsphere.datasource.m1.username = root
spring.shardingsphere.datasource.m1.password = root

# 指定t_order表的数据分布情况，配置数据节点
spring.shardingsphere.sharding.tables.t_order.actual‐data‐nodes = m1.t_order_$‐>{1..2}

# 指定t_order表的主键生成策略为SNOWFLAKE
spring.shardingsphere.sharding.tables.t_order.key‐generator.column=order_id
spring.shardingsphere.sharding.tables.t_order.key‐generator.type=SNOWFLAKE

# 指定t_order表的分片策略，分片策略包括分片键和分片算法
spring.shardingsphere.sharding.tables.t_order.table‐strategy.inline.sharding‐column = order_id
spring.shardingsphere.sharding.tables.t_order.table‐strategy.inline.algorithm‐expression =
t_order_$‐>{order_id % 2 + 1}

# 打开sql输出日志
spring.shardingsphere.props.sql.show = true

swagger.enable = true

logging.level.root = info
logging.level.org.springframework.web = info
logging.level.com.itheima.dbsharding = debug
logging.level.druid.sql = debug

1.首先定义数据源m1，并对m1进行实际的参数配置。
2.指定t_order表的数据分布情况，他分布在m1.t_order_1，m1.t_order_2
3.指定t_order表的主键生成策略为SNOWFLAKE，SNOWFLAKE是一种分布式自增算法，保证id全局唯一
4.定义t_order分片策略，order_id为偶数的数据落在t_order_1，为奇数的落在t_order_2，分表策略的表达式为t_order_$->{order_id % 2 + 1}

2.3.2.数据操作

@Mapper
@Component
public interface OrderDao {
    /**
     * 新增订单
     * @param price 订单价格
     * @param userId 用户id
     * @param status 订单状态
     * @return
     */
    @Insert("insert into t_order(price,user_id,status) value(#{price},#{userId},#{status})")
    int insertOrder(@Param("price") BigDecimal price, @Param("userId") Long userId
        , @Param("status") String status);
    /**
     * 根据id列表查询多个订单
     * @param orderIds 订单id列表
     * @return
     */
    @Select({
        ""
    })
    List < Map > selectOrderbyIds(@Param("orderIds") List < Long > orderIds);
}

2.3.3.测试

编写单元测试：

@RunWith(SpringRunner.class)
@SpringBootTest(classes = {
    ShardingJdbcSimpleDemoBootstrap.class
})
public class OrderDaoTest {
    @Autowired
    private OrderDao orderDao;
    @Test
    public void testInsertOrder() {
        for (int i = 0; i < 10; i++) {
            orderDao.insertOrder(new BigDecimal((i + 1) * 5), 1 L, "WAIT_PAY");
        }
    }
    @Test
    public void testSelectOrderbyIds() {
        List < Long > ids = new ArrayList < > ();
        ids.add(373771636085620736 L);
        ids.add(373771635804602369 L);
        List < Map > maps = orderDao.selectOrderbyIds(ids);
        System.out.println(maps);
    }
}

执行testInsertOrder：

通过日志可以发现order_id为奇数的被插入到t_order_2表，为偶数的被插入到t_order_1表，达到预期目标。
执行testSelectOrderbyIds：

通过日志可以发现，根据传入order_id的奇偶不同，sharding-jdbc分别去不同的表检索数据，达到预期目标。

2.4.流程分析

通过日志分析，Sharding-JDBC在拿到用户要执行的sql之后干了哪些事儿：
（1）解析sql，获取片键值，在本例中是order_id
（2）Sharding-JDBC通过规则配置 t_order_$->{order_id % 2 + 1}，知道了当order_id为偶数时，应该往t_order_1表插数据，为奇数时，往t_order_2插数据。
（3）于是Sharding-JDBC根据order_id的值改写sql语句，改写后的SQL语句是真实所要执行的SQL语句。
（4）执行改写后的真实sql语句
（5）将所有真正执行sql的结果进行汇总合并，返回。

2.5.其他集成方式

Sharding-JDBC不仅可以与spring boot良好集成，它还支持其他配置方式，共支持以下四种集成方式。
Spring Boot Yaml 配置
定义application.yml，内容如下：

server:
  port: 56081
  servlet:
	context‐path: /sharding‐jdbc‐simple‐demo
spring:
  application:
    name: sharding‐jdbc‐simple‐demo
  http:
	encoding:
	enabled: true
	charset: utf‐8
	force: true
  main:
	allow‐bean‐definition‐overriding: true
  shardingsphere:
	datasource:
	  names: m1
	  m1:
		type: com.alibaba.druid.pool.DruidDataSource
		driverClassName: com.mysql.jdbc.Driver
		url: jdbc:mysql://localhost:3306/order_db?useUnicode=true
		username: root
		password: mysql
	sharding:
	  tables:
		t_order:
		  actualDataNodes: m1.t_order_$‐>{1..2}
		  tableStrategy:
			inline:
			  shardingColumn: order_id
			  algorithmExpression: t_order_$‐>{order_id % 2 + 1}
		  keyGenerator:
			type: SNOWFLAKE
			column: order_id
	props:
	  sql:
	  	show: true
mybatis:
  configuration:
	map‐underscore‐to‐camel‐case: true
swagger:
  enable: true
logging:
  level:
	root: info
	org.springframework.web: info
	com.itheima.dbsharding: debug
	druid.sql: debug

如果使用application.yml则需要屏蔽原来的application.properties文件。
Java 配置
添加配置类：

@Configuration
public class ShardingJdbcConfig {
    // 定义数据源
    Map < String, DataSource > createDataSourceMap() {
        DruidDataSource dataSource1 = new DruidDataSource();
        dataSource1.setDriverClassName("com.mysql.jdbc.Driver");
        dataSource1.setUrl("jdbc:mysql://localhost:3306/order_db?useUnicode=true");
        dataSource1.setUsername("root");
        dataSource1.setPassword("root");
        Map < String, DataSource > result = new HashMap < > ();
        result.put("m1", dataSource1);
        return result;
    }
    // 定义主键生成策略
    private static KeyGeneratorConfiguration getKeyGeneratorConfiguration() {
        KeyGeneratorConfiguration result = new
        KeyGeneratorConfiguration("SNOWFLAKE", "order_id");
        return result;
    }
    // 定义t_order表的分片策略
    TableRuleConfiguration getOrderTableRuleConfiguration() {
        TableRuleConfiguration result = new TableRuleConfiguration("t_order", "m1.t_order_$‐> {
                1. .2
            }
            ");
            result.setTableShardingStrategyConfig(new InlineShardingStrategyConfiguration("order_id", "t_order_$‐>{order_id % 2 + 1}")); result.setKeyGeneratorConfig(getKeyGeneratorConfiguration());
            return result;
        }
        // 定义sharding‐Jdbc数据源
        @Bean
        DataSource getShardingDataSource() throws SQLException {
            ShardingRuleConfiguration shardingRuleConfig = new ShardingRuleConfiguration();
            shardingRuleConfig.getTableRuleConfigs()
                .add(getOrderTableRuleConfiguration());
            //spring.shardingsphere.props.sql.show = true
            Properties properties = new Properties();
            properties.put("sql.show", "true");
            return ShardingDataSourceFactory.createDataSource(createDataSourceMap()
                , shardingRuleConfig, properties);
        }
    }
}

由于采用了配置类所以需要屏蔽原来application.properties文件中spring.shardingsphere开头的配置信息。
还需要在SpringBoot启动类中屏蔽使用spring.shardingsphere配置项的类：

@SpringBootApplication(exclude = {SpringBootConfiguration.class})
public class ShardingJdbcSimpleDemoBootstrap {....}

Spring Boot properties配置
此方式同快速入门程序。

# 定义数据源
spring.shardingsphere.datasource.names = m1
spring.shardingsphere.datasource.m1.type = com.alibaba.druid.pool.DruidDataSource
spring.shardingsphere.datasource.m1.driver‐class‐name = com.mysql.jdbc.Driver
spring.shardingsphere.datasource.m1.url = jdbc:mysql://localhost:3306/order_db?useUnicode=true
spring.shardingsphere.datasource.m1.username = root
spring.shardingsphere.datasource.m1.password = root

# 指定t_order表的主键生成策略为SNOWFLAKE
spring.shardingsphere.sharding.tables.t_order.key‐generator.column=order_id
spring.shardingsphere.sharding.tables.t_order.key‐generator.type=SNOWFLAKE

# 指定t_order表的数据分布情况
spring.shardingsphere.sharding.tables.t_order.actual‐data‐nodes = m1.t_order_$‐>{1..2}

# 指定t_order表的分表策略
spring.shardingsphere.sharding.tables.t_order.table‐strategy.inline.sharding‐column = order_id
spring.shardingsphere.sharding.tables.t_order.table‐strategy.inline.algorithm‐expression = t_order_$‐>{order_id % 2 + 1}

Spring命名空间配置
此方式使用xml方式配置，不推荐使用。

<beans xmlns="http://www.springframework.org/schema/beans"
	   xmlns:xsi="http://www.w3.org/2001/XMLSchema‐instance"
	   xmlns:p="http://www.springframework.org/schema/p"
	   xmlns:context="http://www.springframework.org/schema/context"
	   xmlns:tx="http://www.springframework.org/schema/tx"
	   xmlns:sharding="http://shardingsphere.apache.org/schema/shardingsphere/sharding"
	   xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring‐beans.xsd
http://shardingsphere.apache.org/schema/shardingsphere/sharding
http://shardingsphere.apache.org/schema/shardingsphere/sharding/sharding.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring‐context.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring‐tx.xsd">
	<context:annotation‐config />
	<!‐‐定义多个数据源‐‐>
	<bean id="m1" class="com.alibaba.druid.pool.DruidDataSource" destroy‐method="close">
		<property name="driverClassName" value="com.mysql.jdbc.Driver" />
		<property name="url" value="jdbc:mysql://localhost:3306/order_db_1?useUnicode=true" />
		<property name="username" value="root" />
		<property name="password" value="root" />
	bean>
	<!‐‐定义分库策略‐‐>
	<sharding:inline‐strategy id="tableShardingStrategy" sharding‐column="order_id" algorithm‐
							  expression="t_order_$‐>{order_id % 2 + 1}" />
	<!‐‐定义主键生成策略‐‐>
	<sharding:key‐generator id="orderKeyGenerator" type="SNOWFLAKE" column="order_id" />
	<!‐‐定义sharding‐Jdbc数据源‐‐>
	<sharding:data‐source id="shardingDataSource">
		<sharding:sharding‐rule data‐source‐names="m1">
			<sharding:table‐rules>
				<sharding:table‐rule logic‐table="t_order" table‐strategy‐
									 ref="tableShardingStrategy" key‐generator‐ref="orderKeyGenerator" />
			sharding:table‐rules>
		sharding:sharding‐rule>
	sharding:data‐source>
beans>