Spring Boot Spring启动的mysql多个数据源：获取“this.embeddedDatabaseConnection”为空异常

6ie5vjzr  于 2022-11-05  发布在  Spring
关注(0)|答案(1)|浏览(179)

你可以从GitHub克隆完整的更新代码。错误的代码，我在发布这个问题时，是在分支“issue_null_db_details_on_second_time_initialization“
我把我从Sping Boot How-to Guide学到的东西结合起来，在official examples repository中配置多个数据源、多个实体管理器和示例JPA代码，最后得到了下面的代码。

出版日期：

在第一遍中，在“www.example.com“下提供的数据源信息application.properties被适当地考虑，并且
java.lang.NullPointerException: Cannot invoke "org.springframework.boot.jdbc.EmbeddedDatabaseConnection.getDriverClassName()" because "this.embeddedDatabaseConnection" is null
但由于某种原因，同一函数被第二次调用，这一次，没有考虑来自“application.properties“的信息，所有内容都为空。
因此，Sping Boot 认为没有提供外部信息，并尝试按照默认配置进行配置，即认为应用程序是嵌入式数据库。由于（当然）没有提供嵌入式数据库配置，我得到了下面的异常。
java.lang.NullPointerException: Cannot invoke "org.springframework.boot.jdbc.EmbeddedDatabaseConnection.getDriverClassName()" because "this.embeddedDatabaseConnection" is null个
文件名：源代码TwoDataSources.java

@Configuration(proxyBeanMethods = false)
public class TwoDataSources {

    @Bean
    @Primary
    @ConfigurationProperties("app.datasource.first")
    public DataSourceProperties firstDataSourceProperties() {
        return new DataSourceProperties();
    }

    @Bean
    @Primary
    @ConfigurationProperties("app.datasource.first.configuration")
    public HikariDataSource firstDataSource(DataSourceProperties firstDataSourceProperties) {
        return firstDataSourceProperties.initializeDataSourceBuilder().type(HikariDataSource.class).build();
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean firstEntityManagerFactory(DataSource firstDataSource) {
        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();

        LocalContainerEntityManagerFactoryBean factoryBean = new LocalContainerEntityManagerFactoryBean();
        DataSourceProperties firstDataSourceProps = firstDataSourceProperties();
        factoryBean.setDataSource(firstDataSource(firstDataSourceProps));
        factoryBean.setJpaVendorAdapter(vendorAdapter);
        factoryBean.setPackagesToScan(TwoDataSources.class.getPackage().getName());

        return factoryBean;
    }

    @Bean
    @ConfigurationProperties("app.datasource.second")
    public DataSourceProperties secondDataSourceProperties() {
        return new DataSourceProperties();
    }

    @Bean
    @ConfigurationProperties("app.datasource.second.configuration")
    public HikariDataSource secondDataSource(
            @Qualifier("secondDataSourceProperties") DataSourceProperties secondDataSourceProperties) {
        return secondDataSourceProperties.initializeDataSourceBuilder().type(HikariDataSource.class).build();
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean secondEntityManagerFactory(DataSource secondDataSource) {
        HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        vendorAdapter.setGenerateDdl(true);

        LocalContainerEntityManagerFactoryBean factoryBean = new LocalContainerEntityManagerFactoryBean();
        DataSourceProperties secondDataSourceProps = secondDataSourceProperties();
        factoryBean.setDataSource(firstDataSource(secondDataSourceProps));
        factoryBean.setJpaVendorAdapter(vendorAdapter);
        factoryBean.setPackagesToScan(TwoDataSources.class.getPackage().getName());

        return factoryBean;
    }

}

文件名：源代码application.properties

spring.jpa.hibernate.ddl-auto=none

app.datasource.first.url=jdbc:mysql://${MYSQL_HOST:localhost}:3306/first_db
app.datasource.first.username=root
app.datasource.first.password=root
app.datasource.first.configuration.maximum-pool-size=30

app.datasource.second.url=jdbc:mysql://${MYSQL_HOST:localhost}:3306/second_db
app.datasource.second.username=root
app.datasource.second.password=root
app.datasource.second.max-total=30

错误堆栈跟踪：

.   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::               (v2.6.12)

2022-10-06 19:00:10.704  INFO 24638 --- [           main] c.e.a.AccessingDataMysqlApplication      : Starting AccessingDataMysqlApplication using Java 17.0.1 on padmahasa-desktop with PID 24638 (/media/padmahasa/personal/accessing-data-mysql-multiple-datasources/target/classes started by padmahasa in /media/padmahasa/personal/accessing-data-mysql-multiple-datasources)
2022-10-06 19:00:10.708  INFO 24638 --- [           main] c.e.a.AccessingDataMysqlApplication      : No active profile set, falling back to 1 default profile: "default"
2022-10-06 19:00:11.468  INFO 24638 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Bootstrapping Spring Data JPA repositories in DEFAULT mode.
2022-10-06 19:00:11.524  INFO 24638 --- [           main] .s.d.r.c.RepositoryConfigurationDelegate : Finished Spring Data repository scanning in 44 ms. Found 2 JPA repository interfaces.
2022-10-06 19:00:12.301  INFO 24638 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2022-10-06 19:00:12.315  INFO 24638 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2022-10-06 19:00:12.315  INFO 24638 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.65]
2022-10-06 19:00:12.489  INFO 24638 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2022-10-06 19:00:12.490  INFO 24638 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1702 ms
2022-10-06 19:00:12.684  WARN 24638 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'firstEntityManagerFactory' defined in class path resource [com/example/accessingdatamysql/TwoDataSources.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean]: Factory method 'firstEntityManagerFactory' threw exception; nested exception is java.lang.NullPointerException: Cannot invoke "org.springframework.boot.jdbc.EmbeddedDatabaseConnection.getDriverClassName()" because "this.embeddedDatabaseConnection" is null
2022-10-06 19:00:12.691  INFO 24638 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2022-10-06 19:00:12.709  INFO 24638 --- [           main] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2022-10-06 19:00:12.732 ERROR 24638 --- [           main] o.s.boot.SpringApplication               : Application run failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'firstEntityManagerFactory' defined in class path resource [com/example/accessingdatamysql/TwoDataSources.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean]: Factory method 'firstEntityManagerFactory' threw exception; nested exception is java.lang.NullPointerException: Cannot invoke "org.springframework.boot.jdbc.EmbeddedDatabaseConnection.getDriverClassName()" because "this.embeddedDatabaseConnection" is null
    at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:658) ~[spring-beans-5.3.23.jar:5.3.23]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:638) ~[spring-beans-5.3.23.jar:5.3.23]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1352) ~[spring-beans-5.3.23.jar:5.3.23]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1195) ~[spring-beans-5.3.23.jar:5.3.23]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:582) ~[spring-beans-5.3.23.jar:5.3.23]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:542) ~[spring-beans-5.3.23.jar:5.3.23]
    at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:335) ~[spring-beans-5.3.23.jar:5.3.23]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:234) ~[spring-beans-5.3.23.jar:5.3.23]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:333) ~[spring-beans-5.3.23.jar:5.3.23]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:208) ~[spring-beans-5.3.23.jar:5.3.23]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1154) ~[spring-context-5.3.23.jar:5.3.23]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:908) ~[spring-context-5.3.23.jar:5.3.23]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:583) ~[spring-context-5.3.23.jar:5.3.23]
    at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:145) ~[spring-boot-2.6.12.jar:2.6.12]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:745) ~[spring-boot-2.6.12.jar:2.6.12]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:420) ~[spring-boot-2.6.12.jar:2.6.12]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:307) ~[spring-boot-2.6.12.jar:2.6.12]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1317) ~[spring-boot-2.6.12.jar:2.6.12]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1306) ~[spring-boot-2.6.12.jar:2.6.12]
    at com.example.accessingdatamysql.AccessingDataMysqlApplication.main(AccessingDataMysqlApplication.java:12) ~[classes/:na]
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean]: Factory method 'firstEntityManagerFactory' threw exception; nested exception is java.lang.NullPointerException: Cannot invoke "org.springframework.boot.jdbc.EmbeddedDatabaseConnection.getDriverClassName()" because "this.embeddedDatabaseConnection" is null
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:185) ~[spring-beans-5.3.23.jar:5.3.23]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiate(ConstructorResolver.java:653) ~[spring-beans-5.3.23.jar:5.3.23]
    ... 19 common frames omitted
Caused by: java.lang.NullPointerException: Cannot invoke "org.springframework.boot.jdbc.EmbeddedDatabaseConnection.getDriverClassName()" because "this.embeddedDatabaseConnection" is null
    at org.springframework.boot.autoconfigure.jdbc.DataSourceProperties.determineDriverClassName(DataSourceProperties.java:249) ~[spring-boot-autoconfigure-2.6.12.jar:2.6.12]
    at org.springframework.boot.autoconfigure.jdbc.DataSourceProperties.initializeDataSourceBuilder(DataSourceProperties.java:193) ~[spring-boot-autoconfigure-2.6.12.jar:2.6.12]
    at com.example.accessingdatamysql.TwoDataSources.firstDataSource(TwoDataSources.java:37) ~[classes/:na]
    at com.example.accessingdatamysql.TwoDataSources.firstEntityManagerFactory(TwoDataSources.java:46) ~[classes/:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na]
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77) ~[na:na]
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na]
    at java.base/java.lang.reflect.Method.invoke(Method.java:568) ~[na:na]
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:154) ~[spring-beans-5.3.23.jar:5.3.23]
    ... 20 common frames omitted

您可以在“src/main/resources/sql_scripts. sql”下找到SQL语句（在GitHub中为OR）
我是否可以知道为什么在第二次传递时不考虑来自“www.example.com“的数据源信息application.properties，以及如何解决此问题？

  • 谢谢-谢谢

更新1：

正如@bcr666在评论中指出的，我不应该为DataSourceProperties创建一个新对象，而是将“firstDataSourceProps”注入到“firstEntityManagerFactory”中，例如public LocalContainerEntityManagerFactoryBean firstEntityManagerFactory(DataSource firstDataSource, DataSourceProperties firstDataSourceProps)
但现在，我又收到了一个新的错误。


***************************

APPLICATION FAILED TO START

***************************

Description:

A component required a bean named 'entityManagerFactory' that could not be found.

Action:

Consider defining a bean named 'entityManagerFactory' in your configuration.

更新2：

正如在this StackOverflow Answer中提到的，我应该将第二个DB的EntitiManager bean命名为@Bean(name="entityManagerFactory")。

  • 谢谢-谢谢
spring-boot

1条答案

按热度按时间
mklgxw1f

mklgxw1f1#

我想这就是你的问题了，数据源属性firstDataSourceProps =第一个数据源属性（）;。我认为您应该将firstDataSourceProps移除到不同的类中，然后自动将其连接进来，而不是自己执行它。

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