如何在 MySQL 和 MariaDB 中的 spring 启动应用程序中配置多个（两个以上）数据源，

Question

我必须在 spring 引导应用程序中在运行时连接到多个数据源，其中亚马逊 RDS 分别部署了 MySQL 和 MariaDB 实例。 目前，两者都是 MariaDB 个独立存在的实例。 我已经使用了通常的 spring 启动配置，例如Multiple data source and schema creation in Spring Boot

我在这里遇到一个问题，那就是我无法连接到辅助数据源，而我可以连接到主数据源。 下面是一些代码片段。

另外，我想知道在运行时回退到相同模式的其他数据库实例的任何机制，如果原始数据库实例关闭而不影响应用程序或重新启动它。 我对此一无所知。

import com.zaxxer.hikari.HikariDataSource;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

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

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = "a.b.c.d.e",
        entityManagerFactoryRef = "aEntityManagerFactory",
        transactionManagerRef = "aTransactionManager"
)
public class aConfiguration {
    @Bean
    @Primary
    @ConfigurationProperties("app.datasource.a")
    public DataSourceProperties aDataSourceProperties() {
        return new DataSourceProperties();
    }

    @Bean
    @Primary
    @ConfigurationProperties("app.datasource.a.configuration")
    public DataSource aDataSource() {
        return aDataSourceProperties().initializeDataSourceBuilder()
                .type(HikariDataSource.class).build();
    }

    @Bean
    public EntityManagerFactoryBuilder entityManagerFactoryBuilder() {
        return new EntityManagerFactoryBuilder(new HibernateJpaVendorAdapter(), new HashMap<>(), null);
    }

    @Primary
    @Bean(name = "aEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean aEntityManagerFactory(EntityManagerFactoryBuilder builder) {
        return builder
                .dataSource(aDataSource())
                .packages(SomeQualifiedEntity.class)
                .build();
    }

    @Primary
    @Bean
    public PlatformTransactionManager aTransactionManager(
            final @Qualifier("aEntityManagerFactory") LocalContainerEntityManagerFactoryBean aEntityManagerFactory) {
        return new JpaTransactionManager(aEntityManagerFactory.getObject());
    }
}

import com.zaxxer.hikari.HikariDataSource;
import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;
import org.springframework.orm.jpa.JpaTransactionManager;
import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;
import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.annotation.EnableTransactionManagement;

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

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(basePackages = "u.v.w.x.y",
        entityManagerFactoryRef = "bEntityManagerFactory",
        transactionManagerRef = "bTransactionManager"
)
public class aConfiguration {
    @Bean
    @Primary
    @ConfigurationProperties("app.datasource.b")
    public DataSourceProperties bDataSourceProperties() {
        return new DataSourceProperties();
    }

    @Bean
    @Primary
    @ConfigurationProperties("app.datasource.b.configuration")
    public DataSource bDataSource() {
        return bDataSourceProperties().initializeDataSourceBuilder()
                .type(HikariDataSource.class).build();
    }

    @Bean
    public EntityManagerFactoryBuilder entityManagerFactoryBuilder() {
        return new EntityManagerFactoryBuilder(new HibernateJpaVendorAdapter(), new HashMap<>(), null);
    }

    @Primary
    @Bean(name = "bEntityManagerFactory")
    public LocalContainerEntityManagerFactoryBean bEntityManagerFactory(EntityManagerFactoryBuilder builder) {
        return builder
                .dataSource(bDataSource())
                .packages(SomeQualifiedEntity.class)
                .build();
    }

    @Primary
    @Bean
    public PlatformTransactionManager bTransactionManager(
            final @Qualifier("bEntityManagerFactory") LocalContainerEntityManagerFactoryBean bEntityManagerFactory) {
        return new JpaTransactionManager(aEntityManagerFactory.getObject());
    }
}

app.datasource.a.url=
app.datasource.a.username=
app.datasource.a.password=
app.datasource.a.driverClassName=org.mariadb.jdbc.Driver

app.datasource.b.url=
app.datasource.b.username=
app.datasource.b.password=
app.datasource.b.driverClassName=org.mariadb.jdbc.Driver

我希望我可以提供实体和存储库，但我不能。 对不起。

Answer 1

我在 application.properties 文件中的 spring 配置了我的数据库/数据源。 虽然我只有一个数据库，但出于好奇，我尝试了多个数据库，结果成功了。 那么也许在那里试试？ 格式是这样的：

spring.h2.console.enabled=true
spring.datasource.url=jdbc:h2:mem:testdb
spring.data.jpa.repositories.bootstrap-mode=default