springBoot+shardingSphere分库分表java.util.NoSuchElementException: No value bound报错解决

在整合SpringBoot+shardingSphere实现分库分表时，参考官网和其他文章的配置application.yml，出现过各种报错，这里记录一下其中最大的一个问题，研究了好几个小时才解决的。

原有的配置如下：

spring:
  shardingsphere:
    # 配置真实数据源
    dataSource:
      names: ds0,ds1
      # 配置第 1 个数据源
      ds0:
        jdbc-url: jdbc:mysql://192.168.87.112:3308/ds0?useSSL=false&serverTimezone=UTC
        driver-class-name: com.mysql.cj.jdbc.Driver
        password: root
        type: com.zaxxer.hikari.HikariDataSource
        username: root
    # 配置第 2 个数据源
    ds1:
      jdbc-url: jdbc:mysql://192.168.87.112:3309/ds1?useSSL=false&serverTimezone=UTC
      driver-class-name: com.mysql.cj.jdbc.Driver
      password: root
      type: com.zaxxer.hikari.HikariDataSource
      username: root
    rules:
      sharding:
        tables:
          # 配置 t_order 表规则
          t_order:
            actual-data-nodes: ds${0..1}.t_order_${0..15}
            # 配置分库策略
            database-strategy:
              standard:
                sharding-column: user_id
                sharding-algorithm-name: database-inline
            # 配置分表策略
            table-strategy:
              standard:
                sharding-column: order_id
                sharding-algorithm-name: table-inline
        # 配置分片算法
        sharding-algorithms:
          database-inline:
            type: INLINE
            props:
              algorithm-expression: ds$->{user_id % 2}
          table-inline:
            type: INLINE
            props:
              algorithm-expression: t_order_$->{order_id % 16}
          # t_order_item:
          # 省略配置 t_order_item 表规则...
          # ...
    enabled: true
mybatis:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.zym.week07.mutlids2.entity

启动Application，报错信息如下：

百度一波，网上有些文章说要配置key-generators，于是加上后的配置为：

spring:
  shardingsphere:
    # 配置真实数据源
    dataSource:
      names: ds0,ds1
      # 配置第 1 个数据源
      ds0:
        jdbc-url: jdbc:mysql://192.168.87.112:3308/ds0?useSSL=false&serverTimezone=UTC
        driver-class-name: com.mysql.cj.jdbc.Driver
        password: root
        type: com.zaxxer.hikari.HikariDataSource
        username: root
    # 配置第 2 个数据源
    ds1:
      jdbc-url: jdbc:mysql://192.168.87.112:3309/ds1?useSSL=false&serverTimezone=UTC
      driver-class-name: com.mysql.cj.jdbc.Driver
      password: root
      type: com.zaxxer.hikari.HikariDataSource
      username: root
    rules:
      sharding:
        # 序列配置,这个必须配置，否则报错
        key-generators:
          snowflake:
            type: SNOWFLAKE
            props:
              worker-id: 123
        tables:
          # 配置 t_order 表规则
          t_order:
            actual-data-nodes: ds${0..1}.t_order_${0..15}
            # 配置分库策略
            database-strategy:
              standard:
                sharding-column: user_id
                sharding-algorithm-name: database-inline
            # 配置分表策略
            table-strategy:
              standard:
                sharding-column: order_id
                sharding-algorithm-name: table-inline
        # 配置分片算法
        sharding-algorithms:
          database-inline:
            type: INLINE
            props:
              algorithm-expression: ds$->{user_id % 2}
          table-inline:
            type: INLINE
            props:
              algorithm-expression: t_order_$->{order_id % 16}
          # t_order_item:
          # 省略配置 t_order_item 表规则...
          # ...
    enabled: true
mybatis:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.zym.week07.mutlids2.entity

启动后，仍然报错，报错信息还是java.util.NoSuchElementException: No value bound,简直吐血:

但仔细观察日志，发现报错的调用栈有点不太一样，这次的报错主要发生在DataSourceMapSetter#getDataSourceMap这个方法引起，进入方法看下源码：

发现里面要取配置spring.shardingsphere.datasource.common.，也就是说必须要配置公共数据源，且前缀必须是spring.shardingsphere.datasource.common，于是加上后的配置为：

spring:
  shardingsphere:
    # 配置真实数据源
    dataSource:
      names: ds0,ds1
      #配置公共数据源，这个必须配置否则报错
      common:
        driver-class-name: com.mysql.cj.jdbc.Driver
        type: com.zaxxer.hikari.HikariDataSource
        password: root
        username: root
      # 配置第 1 个数据源
      ds0:
        jdbc-url: jdbc:mysql://192.168.87.112:3308/ds0?useSSL=false&serverTimezone=UTC
    # 配置第 2 个数据源
      ds1:
        jdbc-url: jdbc:mysql://192.168.87.112:3309/ds1?useSSL=false&serverTimezone=UTC
    rules:
      sharding:
        # 序列配置,这个必须配置，否则报错
        key-generators:
          snowflake:
            type: SNOWFLAKE
            props:
              worker-id: 123
        tables:
          # 配置 t_order 表规则
          t_order:
            actual-data-nodes: ds${0..1}.t_order_${0..15}
            # 配置分库策略
            database-strategy:
              standard:
                sharding-column: user_id
                sharding-algorithm-name: database-inline
            # 配置分表策略
            table-strategy:
              standard:
                sharding-column: order_id
                sharding-algorithm-name: table-inline
        # 配置分片算法
        sharding-algorithms:
          database-inline:
            type: INLINE
            props:
              algorithm-expression: ds$->{user_id % 2}
          table-inline:
            type: INLINE
            props:
              algorithm-expression: t_order_$->{order_id % 16}
          # t_order_item:
          # 省略配置 t_order_item 表规则...
          # ...
    enabled: true
mybatis:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl
  mapper-locations: classpath:mapper/*.xml
  type-aliases-package: com.zym.week07.mutlids2.entity

启动后，终于成功。