我尝试在MKyong's example之后使用Sping Boot 创建一个非Web应用程序，但我收到了以下错误：

.   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.0.5.RELEASE)

(...) Several not relevant INFO log lines

2018-12-12 11:45:29.420 ERROR 30866 --- [ main] com.zaxxer.hikari.HikariConfig           : Failed to load driver class org.postgresql.Driver from HikariConfig class classloader sun.misc.Launcher$AppClassLoader@18b4aac2
2018-12-12 11:45:29.423  WARN 30866 --- [ main] s.c.a.AnnotationConfigApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.boot.context.properties.ConfigurationPropertiesBindException: Error creating bean with name 'ldConfiguration': Could not bind properties to 'LdConfiguration' : prefix=datasources.ld, ignoreInvalidFields=false, ignoreUnknownFields=true; nested exception is org.springframework.boot.context.properties.bind.BindException: Failed to bind properties under 'datasources.ld' to es.ortoplus.LdConfiguration$$EnhancerBySpringCGLIB$$625f0f64
2018-12-12 11:45:29.435  INFO 30866 --- [ main] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2018-12-12 11:45:29.440 ERROR 30866 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
APPLICATION FAILED TO START
***************************

Description:

Failed to bind properties under 'datasources.ld' to es.oplus.LdConfiguration$$EnhancerBySpringCGLIB$$625f0f64:

    Property: datasources.ld.driverclassname
    Value: org.postgresql.Driver
    Origin: class path resource [application.yml]:3:22
    Reason: Failed to load driver class org.postgresql.Driver in either of HikariConfig class loader or Thread context classloader

Action:

Update your application's configuration

我的配置文件（application.yml）是

datasources:
  ld:
    driverClassName: org.postgresql.Driver
    jdbc-url: jdbc:postgresql://localhost:5432/oplus
    username: user123
    password: 123456
    connection-test-query: SELECT 1

在我的Maven pom.xml文件中，我添加了：

<dependency>
  <groupId>org.postgresql</groupId>
  <artifactId>postgresql</artifactId>
  <!--<version> (managed by Spring Boot)42.2.5 </version> -->
</dependency>

我的入口点类：

@SpringBootApplication
public class App implements CommandLineRunner {

    @Autowired private UsuarioRepository usuarioRep;
    @Override
    public void run(String... args) throws Exception {
        App app = new App();
        System.out.printf("Users: %1d", app.usuarioRep.count());

    }

    public static void main(String[] args) throws ClassNotFoundException {
        //Class.forName("org.postgresql.Driver");
        SpringApplication.run(App.class, args);

    }

}

正如您所看到的，我尝试检查类是否已经在类路径中。如果我取消注解该行，我会得到一个ClassNotFoundException异常，所以看起来这个错误是因为Maven没有包含依赖项而导致的。我尝试将作用域设置为runtime，但它仍然失败。
无论如何，这是我的配置类：

@Configuration
@ConfigurationProperties(prefix = "datasources.ld")
@EnableTransactionManagement
@EnableJpaRepositories(entityManagerFactoryRef = "postgreEntityManagerFactory", transactionManagerRef = "postgreTransactionManager",
        basePackages = "es.plus.l.dao")
public class LdConfiguration extends HikariConfig {

    @Bean(name = "postgreDataSource")
    @Primary
    public DataSource dataSource() {
        return new HikariDataSource(this);
    }

    @Bean(name = "postgreEntityManagerFactory")
    @Primary
    public LocalContainerEntityManagerFactoryBean postgreEntityManagerFactory(
            final EntityManagerFactoryBuilder builder,
            @Qualifier("postgreDataSource") final DataSource dataSource) {
        final LocalContainerEntityManagerFactoryBean entityManagerFactoryBean = new LocalContainerEntityManagerFactoryBean();
        entityManagerFactoryBean.setJpaVendorAdapter(this.vendorAdaptor());
        entityManagerFactoryBean.setDataSource(dataSource);
        entityManagerFactoryBean.setPersistenceProviderClass(HibernatePersistenceProvider.class);
        entityManagerFactoryBean.setPersistenceUnitName("postgre");
        entityManagerFactoryBean.setPackagesToScan("es.oplus.ld.model");
        entityManagerFactoryBean.setJpaProperties(this.jpaHibernateProperties());
        entityManagerFactoryBean.afterPropertiesSet();
        return entityManagerFactoryBean;
    }

    @Bean(name = "postgreTransactionManager")
    @Primary
    public PlatformTransactionManager postgreTransactionManager(
          @Qualifier("postgreEntityManagerFactory") final EntityManagerFactory emf) {
        return new JpaTransactionManager(emf);
    }

    private HibernateJpaVendorAdapter vendorAdaptor() {
        final HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();
        // put all the adapter properties here, such as show sql
        return vendorAdapter;
    }

    private Properties jpaHibernateProperties() {
        final Properties properties = new Properties();
        // put all required jpa propeties here
        return properties;
    }

}