如何在 MySQL 和 MariaDB 中的 spring 啟動應用程序中配置多個（兩個以上）數據源，

Question

我必須在 spring 引導應用程序中在運行時連接到多個數據源，其中亞馬遜 RDS 分別部署了 MySQL 和 MariaDB 實例。 目前，兩者都是 MariaDB 個獨立存在的實例。 我已經使用了通常的 spring 啟動配置，例如Multiple data source and schema creation in Spring Boot

我在這里遇到一個問題，那就是我無法連接到輔助數據源，而我可以連接到主數據源。 下面是一些代碼片段。

另外，我想知道在運行時回退到相同模式的其他數據庫實例的任何機制，如果原始數據庫實例關閉而不影響應用程序或重新啟動它。 我對此一無所知。

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

我希望我可以提供實體和存儲庫，但我不能。 對不起。

Answer 1

我在 application.properties 文件中的 spring 配置了我的數據庫/數據源。 雖然我只有一個數據庫，但出於好奇，我嘗試了多個數據庫，結果成功了。 那么也許在那里試試？ 格式是這樣的：

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