《微服务实战》第三十一章 ShardingSphere - ShardingSphere-JDBC

川长思鸟来 2023-10-12 14:03 10阅读 0赞

## 前言 ##

Apache ShardingSphere 是一款分布式的数据库生态系统， 可以将任意数据库转换为分布式数据库，并通过数据分片、弹性伸缩、加密等能力对原有数据库进行增强。

Apache ShardingSphere 设计哲学为 Database Plus，旨在构建异构数据库上层的标准和生态。 它关注如何充分合理地利用数据库的计算和存储能力，而并非实现一个全新的数据库。 它站在数据库的上层视角，关注它们之间的协作多于数据库自身。

## 1、ShardingSphere-JDBC ##

ShardingSphere-JDBC 定位为轻量级 Java 框架，在 Java 的 JDBC 层提供的额外服务。

### 1.1、应用场景 ###

Apache ShardingSphere-JDBC 可以通过Java 和 YAML 这 2 种方式进行配置，开发者可根据场景选择适合的配置方式。

*  数据库读写分离
 *  数据库分表分库

### 1.2、原理 ###

*  Sharding-JDBC中的路由结果是通过分片字段和分片方法来确定的,如果查询条件中有 id 字段的情况还好，查询将会落到某个具体的分片
 *  如果查询没有分片的字段，会向所有的db或者是表都会查询一遍，让后封装结果集给客户端。  
    ![在这里插入图片描述][3d7e57ec7972402683e8b0829153a6ba.png]

### 1.3、spring boot整合 ###

#### 1.3.1、添加依赖 ####

<dependency>
        <groupId>org.apache.shardingsphere</groupId>
        <artifactId>sharding-jdbc-spring-boot-starter</artifactId>
        <version>4.1.1</version>
    </dependency>

#### 1.3.2、添加配置 ####

spring:
      main:
        # 一个实体类对应多张表，覆盖
        allow-bean-definition-overriding: true
      shardingsphere:
        datasource:
          ds0:
            #配置数据源具体内容，包含连接池，驱动，地址，用户名和密码
            driver-class-name: com.mysql.cj.jdbc.Driver
            jdbc-url: jdbc:mysql://127.0.0.1:3306/account?autoReconnect=true&allowMultiQueries=true
            password: root
            type: com.zaxxer.hikari.HikariDataSource
            username: root
          ds1:
            driver-class-name: com.mysql.cj.jdbc.Driver
            jdbc-url: jdbc:mysql://127.0.0.1:3306/account?autoReconnect=true&allowMultiQueries=true
            password: root
            type: com.zaxxer.hikari.HikariDataSource
            username: root
          # 配置数据源，给数据源起名称
          names: ds0,ds1
        props:
          sql:
            show: true
        sharding:
          tables:
            user_info:
              #指定 user_info 表分布情况，配置表在哪个数据库里面，表名称都是什么
              actual-data-nodes: ds0.user_info_${
        0..9}
              database-strategy:
                standard:
                  preciseAlgorithmClassName: com.xxxx.store.account.config.PreciseDBShardingAlgorithm
                  rangeAlgorithmClassName: com.xxxx.store.account.config.RangeDBShardingAlgorithm
                  sharding-column: id
              table-strategy:
                standard:
                  preciseAlgorithmClassName: com.xxxx.store.account.config.PreciseTablesShardingAlgorithm
                  rangeAlgorithmClassName: com.xxxx.store.account.config.RangeTablesShardingAlgorithm
                  sharding-column: id

#### 1.3.3、制定分片算法 ####

##### 1.3.3.1、精确分库算法 #####

/**
     * 精确分库算法
     */
    public class PreciseDBShardingAlgorithm implements PreciseShardingAlgorithm<Long> {
        
        /**
         *
         * @param availableTargetNames 配置所有的列表
         * @param preciseShardingValue 分片值
         * @return
         */
        @Override
        public String doSharding(Collection<String> availableTargetNames, PreciseShardingValue<Long> preciseShardingValue) {
        
            Long value = preciseShardingValue.getValue();
            //后缀 0，1
            String postfix = String.valueOf(value % 2);
    
            for (String availableTargetName : availableTargetNames) {
        
                if(availableTargetName.endsWith(postfix)){
        
                    return availableTargetName;
                }
            }
    
            throw new UnsupportedOperationException();
        }
    
    }

##### 1.3.3.2、范围分库算法 #####

/**
     * 范围分库算法
     */
    public class RangeDBShardingAlgorithm implements RangeShardingAlgorithm<Long> {
        
    
    
        @Override
        public Collection<String> doSharding(Collection<String> collection, RangeShardingValue<Long> rangeShardingValue) {
        
            return collection;
        }
    }

##### 1.3.3.3、精确分表算法 #####

/**
     * 精确分表算法
     */
    public class PreciseTablesShardingAlgorithm implements PreciseShardingAlgorithm<Long> {
        
        /**
         *
         * @param availableTargetNames 配置所有的列表
         * @param preciseShardingValue 分片值
         * @return
         */
        @Override
        public String doSharding(Collection<String> availableTargetNames, PreciseShardingValue<Long> preciseShardingValue) {
        
            Long value = preciseShardingValue.getValue();
            //后缀
            String postfix = String.valueOf(value % 10);
    
            for (String availableTargetName : availableTargetNames) {
        
                if(availableTargetName.endsWith(postfix)){
        
                    return availableTargetName;
                }
            }
    
            throw new UnsupportedOperationException();
        }
    
    }

##### 1.3.3.4、范围分表算法 #####

/**
     * 范围分表算法
     */
    public class RangeTablesShardingAlgorithm implements RangeShardingAlgorithm<Long> {
        
    
        @Override
        public Collection<String> doSharding(Collection<String> collection, RangeShardingValue<Long> rangeShardingValue) {
        
    
            Collection<String> result = new ArrayList<>();
            Range<Long> valueRange = rangeShardingValue.getValueRange();
            Long start = valueRange.lowerEndpoint();
            Long end = valueRange.upperEndpoint();
    
            Long min = start % 10;
            Long max = end % 10;
    
            for (Long i = min; i < max +1; i++) {
        
                Long finalI = i;
                collection.forEach(e -> {
        
                    if(e.endsWith(String.valueOf(finalI))){
        
                        result.add(e);
                    }
                });
            }
            return result;
        }
    
    }

#### 1.3.4、数据库建表 ####

DROP TABLE IF EXISTS `user_info_0`;
    CREATE TABLE `user_info_0` (
      `id` bigint(20) NOT NULL,
      `account` varchar(255) DEFAULT NULL,
      `user_name` varchar(255) DEFAULT NULL,
      `pwd` varchar(255) DEFAULT NULL,
      PRIMARY KEY (`id`)
    ) ENGINE=InnoDB DEFAULT CHARSET=utf8;

#### 1.3.5、业务应用 ####

##### 1.3.5.1、定义实体类 #####

@Data
    @TableName(value = "user_info")
    public class UserInfo {
        
        /**
         * 主键
         */
        private Long id;
        /**
         * 账号
         */
        private String account;
        /**
         * 用户名
         */
        private String userName;
        /**
         * 密码
         */
        private String pwd;
    
    }

##### 1.3.5.2、定义接口 #####

public interface UserInfoService{
        
        /**
         * 保存
         * @param userInfo
         * @return
         */
        public UserInfo saveUserInfo(UserInfo userInfo);
    
        public UserInfo getUserInfoById(Long id);
    
        public List<UserInfo> listUserInfo();
    }

##### 1.3.5.3、实现类 #####

@Service
    public class UserInfoServiceImpl extends ServiceImpl<UserInfoMapper, UserInfo> implements UserInfoService {
        
    
        @Override
        @Transactional
        public UserInfo saveUserInfo(UserInfo userInfo) {
        
            userInfo.setId(IdUtils.getId());
            this.save(userInfo);
            return userInfo;
        }
    
        @Override
        public UserInfo getUserInfoById(Long id) {
        
    
            return this.getById(id);
        }
    
        @Override
        public List<UserInfo> listUserInfo() {
        
            QueryWrapper<UserInfo> userInfoQueryWrapper = new QueryWrapper<>();
            userInfoQueryWrapper.between("id",1623695688380448768L,1623695688380448769L);
            return this.list(userInfoQueryWrapper);
        }
    }

#### 1.3.6、生成ID - 雪花算法 ####

package com.xxxx.tore.common.utils;
    
    import cn.hutool.core.lang.Snowflake;
    import cn.hutool.core.util.IdUtil;
    
    /**
     * 生成各种组件ID
     */
    public class IdUtils {
        
    
        /**
         * 雪花算法
         * @return
         */
        public static long getId(){
        
            Snowflake snowflake = IdUtil.getSnowflake(0, 0);
            long id = snowflake.nextId();
            return id;
        }
    }

### 1.4、seata与sharding-jdbc整合 ###

https://github.com/seata/seata-samples/tree/master/springcloud-seata-sharding-jdbc-mybatis-plus-samples

#### 1.4.1、common中添加依赖 ####

<dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
        <version>2021.0.4.0</version>
    </dependency>
    
    <dependency>
        <groupId>org.apache.shardingsphere</groupId>
        <artifactId>sharding-transaction-base-seata-at</artifactId>
        <version>4.1.1</version>
    </dependency>
    
    <dependency>
        <groupId>com.alibaba.cloud</groupId>
        <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
        <version>2021.0.4.0</version>
        <exclusions>
            <exclusion>
                <groupId>com.alibaba.nacos</groupId>
                <artifactId>nacos-client</artifactId>
            </exclusion>
        </exclusions>
    </dependency>
    <dependency>
        <groupId>com.alibaba.nacos</groupId>
        <artifactId>nacos-client</artifactId>
        <version>1.4.2</version>
    </dependency>

#### 1.4.2、改造account-service服务 ####

@Service
    public class AccountServiceImpl extends ServiceImpl<AccountMapper, Account> implements AccountService {
        
        @Autowired
        private OrderService orderService;
        @Autowired
        private StorageService storageService;
    
        /**
         * 存放商品编码及其对应的价钱
         */
        private static Map<String,Integer> map = new HashMap<>();
        static {
        
            map.put("c001",3);
            map.put("c002",5);
            map.put("c003",10);
            map.put("c004",6);
    
        }
        @Override
        @Transactional
        @ShardingTransactionType(TransactionType.BASE)
        public void debit(OrderDTO orderDTO) {
        
            //扣减账户余额
            int calculate = this.calculate(orderDTO.getCommodityCode(), orderDTO.getCount());
    
            AccountDTO accountDTO = new AccountDTO(orderDTO.getUserId(), calculate);
    
            QueryWrapper<Account> objectQueryWrapper = new QueryWrapper<>();
            objectQueryWrapper.eq("id",1);
            objectQueryWrapper.eq(accountDTO.getUserId() != null,"user_id",accountDTO.getUserId());
    
            Account account = this.getOne(objectQueryWrapper);
            account.setMoney(account.getMoney() - accountDTO.getMoney());
            this.saveOrUpdate(account);
    
            //扣减库存
            this.storageService.deduct(new StorageDTO(null,orderDTO.getCommodityCode(),orderDTO.getCount()));
            //生成订单
            this.orderService.create(orderDTO);      
        }
    
        /**
         * 计算购买商品的总价钱
         * @param commodityCode
         * @param orderCount
         * @return
         */
        private int calculate(String commodityCode, int orderCount){
        
            //商品价钱
            Integer price = map.get(commodityCode) == null ? 0 : map.get(commodityCode);
            return price * orderCount;
        }
    }

注意：调单生成调用的逻辑修改，减余额->减库存->生成订单。调用入口方法注解加上：`@ShardingTransactionType(TransactionType.BASE)`

#### 1.4.3、修改business-service服务 ####

@Service
    public class BusinessServiceImpl implements BusinessService {
        
        @Autowired
        private OrderService orderService;
        @Autowired
        private StorageService storageService;
        @Autowired
        private AccountService accountService;
    
        @Override
        public void purchase(OrderDTO orderDTO) {
        
            //扣减账号中的钱
            accountService.debit(orderDTO);        
        }
    }

#### 1.4.4、修改order-service服务 ####

@Service
    public class OrderServiceImpl extends ServiceImpl<OrderMapper,Order> implements OrderService {
        
    
        /**
         * 存放商品编码及其对应的价钱
         */
        private static Map<String,Integer> map = new HashMap<>();
        static {
        
            map.put("c001",3);
            map.put("c002",5);
            map.put("c003",10);
            map.put("c004",6);
        }
        @Override
        @Transactional
        @ShardingTransactionType(TransactionType.BASE)
        public Order create(String userId, String commodityCode, int orderCount) {
        
            int orderMoney = calculate(commodityCode, orderCount);
    
            Order order = new Order();
            order.setUserId(userId);
            order.setCommodityCode(commodityCode);
            order.setCount(orderCount);
            order.setMoney(orderMoney);
            
            //保存订单
            this.save(order);
            try {
        
                TimeUnit.SECONDS.sleep(30);
            } catch (InterruptedException e) {
        
                e.printStackTrace();
            }
            if(true){
        
                throw new RuntimeException("回滚测试");
            }
            return order;
        }
    
        /**
         * 计算购买商品的总价钱
         * @param commodityCode
         * @param orderCount
         * @return
         */
        private int calculate(String commodityCode, int orderCount){
        
            //商品价钱
            Integer price = map.get(commodityCode) == null ? 0 : map.get(commodityCode);
            return price * orderCount;
        }
    }

#### 1.4.5、配置文件参考 ####

server:
      port: 8090
    
    spring:
      main:
        # 一个实体类对应多张表，覆盖
        allow-bean-definition-overriding: true
      shardingsphere:
        datasource:
          ds0:
            #配置数据源具体内容，包含连接池，驱动，地址，用户名和密码
            driver-class-name: com.mysql.cj.jdbc.Driver
            jdbc-url: jdbc:mysql://127.0.0.1:3306/account?autoReconnect=true&allowMultiQueries=true
            password: root
            type: com.zaxxer.hikari.HikariDataSource
            username: root
          ds1:
            driver-class-name: com.mysql.cj.jdbc.Driver
            jdbc-url: jdbc:mysql://127.0.0.1:3306/account?autoReconnect=true&allowMultiQueries=true
            password: root
            type: com.zaxxer.hikari.HikariDataSource
            username: root
          # 配置数据源，给数据源起名称
          names: ds0,ds1
        props:
          sql:
            show: true
        sharding:
          tables:
            account_tbl:
              actual-data-nodes: ds0.account_tbl_${
        0..1}
              database-strategy:
                standard:
                  preciseAlgorithmClassName: com.xxxx.store.account.config.PreciseDBExtShardingAlgorithm
                  #rangeAlgorithmClassName: com.xxxx.store.account.config.RangeDBShardingAlgorithm
                  sharding-column: id
              table-strategy:
                standard:
                  preciseAlgorithmClassName: com.xxxx.store.account.config.PreciseTablesExtShardingAlgorithm
                  #rangeAlgorithmClassName: com.xxxx.store.account.config.RangeTablesShardingAlgorithm
                  sharding-column: id
    
            user_info:
              #指定 user_info 表分布情况，配置表在哪个数据库里面，表名称都是什么
              actual-data-nodes: ds0.user_info_${
        0..9}
              database-strategy:
                standard:
                  preciseAlgorithmClassName: com.xxxx.store.account.config.PreciseDBShardingAlgorithm
                  rangeAlgorithmClassName: com.xxxx.store.account.config.RangeDBShardingAlgorithm
                  sharding-column: id
              table-strategy:
                standard:
                  preciseAlgorithmClassName: com.xxxx.store.account.config.PreciseTablesShardingAlgorithm
                  rangeAlgorithmClassName: com.xxxx.store.account.config.RangeTablesShardingAlgorithm
                  sharding-column: id
    
    
    
    
      #以上是sharding-jdbc配置
      cloud:
        nacos:
          discovery:
            server-addr: localhost:8848
            namespace: 1ff3782d-b62d-402f-8bc4-ebcf40254d0a
      application:
        name: account-service  #微服务名称
    #  datasource:
    #    username: root
    #    password: root
    #    url: jdbc:mysql://127.0.0.1:3306/account
    #    driver-class-name: com.mysql.cj.jdbc.Driver
    
    seata:
      enabled: true
      enable-auto-data-source-proxy: false
      application-id: account-service
      tx-service-group: default_tx_group
      service:
        vgroup-mapping:
          default_tx_group: default
        disable-global-transaction: false
      registry:
        type: nacos
        nacos:
          application: seata-server
          server-addr: 127.0.0.1:8848
          namespace: 1ff3782d-b62d-402f-8bc4-ebcf40254d0a
          group: SEATA_GROUP
          username: nacos
          password: nacos
      config:
        nacos:
          server-addr: 127.0.0.1:8848
          namespace: 1ff3782d-b62d-402f-8bc4-ebcf40254d0a
          group: SEATA_GROUP
          username: nacos
          password: nacos

[3d7e57ec7972402683e8b0829153a6ba.png]: https://img-blog.csdnimg.cn/3d7e57ec7972402683e8b0829153a6ba.png