Sharding-JDBC(ShardingSphere)多数据库与springboot集成 -- 读写分离

Sharding-JDBC(ShardingSphere)作为分布式数据库中间件,在Java的JDBC层提供的额外服务。它使用客户端直连数据库，以jar包形式提供服务。引入sharding-jdbc-spring-boot-starter可以快速完成与springboot的集成; 但是默认情况下只能支持到一个数据库，如果支持多数据库，需要做部分扩展；本文记录支持多数据库所做的扩展。

引入依赖

<dependency>
  <groupId>org.apache.shardingsphere</groupId>
  <artifactId>sharding-jdbc-spring-boot-starter</artifactId>
  <version>4.0.1</version>
</dependency>

扩展部分

• 实现EnvironmentAware接口 ，在方法setEnvironment解析properties配置可以获取所有配置信息

• 获取以spring.ydal为前缀的所有数据库配置

  Map<String, Object> databases = PropertyUtil.handle(environment, "spring.ydal" , Map.class);

• 构造每个数据库的数据库的MasterSlave数据源

   Map<String, Object> dataSourceProps = PropertyUtil.handle(environment, "spring.eldal." + dataBaseName+"datasource", Map.class);
   Preconditions.checkState(!dataSourceProps.isEmpty(), "Wrong datasource properties!");
  
   DataSource datasource = DataSourceUtil.getDataSource(dataSourceProps.get("type").toString(), dataSourceProps);
   Optional<DataSourcePropertiesSetter> dataSourcePropertiesSetter = DataSourcePropertiesSetterHolder.getDataSourcePropertiesSetterByType(dataSourceProps.get("type").toString());
   if (dataSourcePropertiesSetter.isPresent()) {
       dataSourcePropertiesSetter.get().propertiesSet(environment, prefix, dataSourceName, datasource);
   }
  
  masterSlaveRule = PropertyUtil.handle(environment, "spring.eldal." + dataBaseName+".masterslave", YamlMasterSlaveRuleConfiguration.class);
  MasterSlaveRuleConfiguration msConfig = new MasterSlaveRuleConfigurationYamlSwapper().swap(masterSlaveRule);
  
  Properties dsProps = PropertyUtil.handle(environment, "spring.eldal." + dataBaseName+".props", Properties.class);
  MasterSlaveDataSourceFactory.createDataSource(datasource, msConfig, dsProps)

禁用ShardingSphere的Springboot的自动配置

实现该扩展后以jar包的形式提供出去供多个项目使用，所以我们必须在jar里面禁用ShardingSphere的Springboot的自动配置；可以实现如下接口:

public class YdalAutoConfigurationImportFilter implements AutoConfigurationImportFilter {
    private static final Set<String> SHOULD_SKIP = new HashSet<>(
            Arrays.asList("org.apache.shardingsphere.shardingjdbc.spring.boot.SpringBootConfiguration"));
    @Override
    public boolean[] match(String[] autoConfigurationClasses, AutoConfigurationMetadata autoConfigurationMetadata) {
        boolean[] matches = new boolean[autoConfigurationClasses.length];

        for(int i = 0; i< autoConfigurationClasses.length; i++) {
            matches[i] = !SHOULD_SKIP.contains(autoConfigurationClasses[i]);
        }
        return matches;
    }
}

• 将YdalAutoConfigurationImportFilter加入META-INF/spring.factories

最后

• 详细代码： https://github.com/yinghuzhu/ydal-spring-boot-starter