我正在尝试按照 MKyong 的示例使用 Spring Boot 创建一个非 Web 应用程序，但出现以下错误：
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: 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conf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 文件中添加：
<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);
}
}
如您所见，我尝试检查该类是否已在类路径中。如果我取消注释该行，我会得到一个 ClassNotFoundException，所以看来错误是因为 Maven 不包含依赖项而引起的。我尝试将范围设置为
runtime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;
}
}
我发现了问题：Eclipse正确显示了依赖关系，但由于该类似乎并不真正存在，所以我尝试手动运行它，所以当我执行时：
mvn clean install
我从 Maven 收到此错误
error reading /home/pablo/.m2/repository/org/postgresql/postgresql/42.2.5/postgresql-42.2.5.jar; invalid LOC header (bad signature)
所以错误是由于 Maven 下载了损坏版本的 jar 引起的。
删除它以强制重新下载解决了该问题。
将下一个代码添加到 pom.xml:
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
<scope>runtime</scope>
</dependency>
确保 pom.xml 中具有 JDBC 驱动程序和 PostgreSQL 依赖项，如下所示：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
<scope>runtime</scope>
</dependency>
在我的例子中，pom.xml 缺少以下依赖项。添加以下代码并且应该可以正常工作：
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
<scope>runtime</scope>
</dependency>
如果您正在使用 IntelliJ Idea，请重新启动 IDE
如果有人在使用 IntelliJ Idea 的 Spring Boot 3 中遇到同样的问题，只需删除 postgresql 依赖项，重新加载 Maven 项目，再次添加回来并重新加载 Maven 项目