错误：应用程序上下文中某些bean的依赖关系形成了一个循环

Question

我正在我的 Spring 应用程序中实现多租户架构。

ConfigurationDataSource

类用于在应用程序启动时提供

DataSource

。下面是该类的详细实现：

ConfigurationDataSource

import com.example.hikaricp_demo.domain.TenantConfig;
import com.example.hikaricp_demo.repository.TenantConfigRepository;
import com.zaxxer.hikari.HikariConfig;
import com.zaxxer.hikari.HikariDataSource;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.jdbc.datasource.lookup.AbstractRoutingDataSource;

import javax.sql.DataSource;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

@Configuration
public class ConfigurationDataSource {

    @Autowired
    private TenantConfigRepository repository;

    private List<TenantConfig> getListTenant(){
        return repository.findAll();
    }

    TenantConfig tenantDefault() {
        return repository.findByTenantId("tenantDefault");
    }

    @Bean
    public DataSource dataSource() {
        Map<Object, Object> resolvedDataSources = new HashMap<>();
        List<TenantConfig> listTenant = getListTenant();

        for (TenantConfig item : listTenant) {
            HikariConfig hikariConfig = new HikariConfig();
            hikariConfig.setDriverClassName(item.getDriverClassName());
            hikariConfig.setJdbcUrl(item.getUrl());
            hikariConfig.setUsername(item.getUsername());
            hikariConfig.setPassword(item.getPassword());
            hikariConfig.setSchema(item.getSchema());

            HikariDataSource dataSource = new HikariDataSource(hikariConfig);
            resolvedDataSources.put(item.getTenantId(), dataSource);
        }

        AbstractRoutingDataSource dataSource = new MultiTenantDataSource();
        dataSource.setDefaultTargetDataSource(tenantDefault());
        dataSource.setTargetDataSources(resolvedDataSources);
        dataSource.afterPropertiesSet();
        return dataSource;
    }
}

TenantConfigRepository

是一个 Spring Data JPA 存储库，它与数据库交互以获取租户配置。当我运行该应用程序时，出现以下错误：

Description:

The dependencies of some of the beans in the application context form a cycle:

   entityManagerFactory defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaConfiguration.class]
┌─────┐
|  dataSourceScriptDatabaseInitializer defined in class path resource [org/springframework/boot/autoconfigure/sql/init/DataSourceInitializationConfiguration.class]
↑     ↓
|  configurationDataSource (field private com.example.hikaricp_demo.repository.TenantConfigRepository com.example.hikaricp_demo.config.ConfigurationDataSource.repository)
↑     ↓
|  tenantConfigRepository defined in com.example.hikaricp_demo.repository.TenantConfigRepository defined in @EnableJpaRepositories declared on JpaRepositoriesRegistrar.EnableJpaRepositoriesConfiguration
↑     ↓
|  jpaSharedEM_entityManagerFactory
└─────┘

我怀疑发生这种情况是因为：

dataSource bean 依赖于

TenantConfigRepository

（使用repository.findAll() 获取租户配置）。

TenantConfigRepository

也可能依赖于

DataSource

，从而创建循环依赖。

Answer 1

@Bean
@Lazy
public DataSource dataSource() {
    //your code
}