Spring Boot 1.4：类路径资源 [] 无法解析为 URL，因为它不存在

Question

没有 JPA 的项目在 1.3 中可以正常工作，但在 1.4 中会引发以下异常：

2016-07-31_19:29:21.758 [main] ERROR org.springframework.boot.SpringApplication - Application startup failed
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/HibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: Unable to resolve persistence unit root URL
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1578) ~[spring-beans-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545) ~[spring-beans-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482) ~[spring-beans-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1076) ~[spring-context-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:851) ~[spring-context-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:541) ~[spring-context-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.4.0.RELEASE.jar!/:1.4.0.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:759) [spring-boot-1.4.0.RELEASE.jar!/:1.4.0.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:369) [spring-boot-1.4.0.RELEASE.jar!/:1.4.0.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:313) [spring-boot-1.4.0.RELEASE.jar!/:1.4.0.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1185) [spring-boot-1.4.0.RELEASE.jar!/:1.4.0.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1174) [spring-boot-1.4.0.RELEASE.jar!/:1.4.0.RELEASE]
    at at.oebb.ticketshop.automat.backend.Application.main(Application.java:21) [classes!/:na]
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_31]
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_31]
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[na:1.8.0_31]
    at java.lang.reflect.Method.invoke(Unknown Source) ~[na:1.8.0_31]
    at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48) [ts-automat-0.0.1.jar:na]
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:87) [ts-automat-0.0.1.jar:na]
    at org.springframework.boot.loader.Launcher.launch(Launcher.java:50) [ts-automat-0.0.1.jar:na]
    at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:58) [ts-automat-0.0.1.jar:na]
Caused by: javax.persistence.PersistenceException: Unable to resolve persistence unit root URL
    at org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager.determineDefaultPersistenceUnitRootUrl(DefaultPersistenceUnitManager.java:603) ~[spring-orm-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager.preparePersistenceUnitInfos(DefaultPersistenceUnitManager.java:443) ~[spring-orm-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager.afterPropertiesSet(DefaultPersistenceUnitManager.java:424) ~[spring-orm-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean.createNativeEntityManagerFactory(LocalContainerEntityManagerFactoryBean.java:310) ~[spring-orm-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.buildNativeEntityManagerFactory(AbstractEntityManagerFactoryBean.java:373) ~[spring-orm-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.afterPropertiesSet(AbstractEntityManagerFactoryBean.java:362) ~[spring-orm-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1637) ~[spring-beans-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1574) ~[spring-beans-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    ... 24 common frames omitted
Caused by: java.io.FileNotFoundException: class path resource [] cannot be resolved to URL because it does not exist
    at org.springframework.core.io.ClassPathResource.getURL(ClassPathResource.java:187) ~[spring-core-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    at org.springframework.orm.jpa.persistenceunit.DefaultPersistenceUnitManager.determineDefaultPersistenceUnitRootUrl(DefaultPersistenceUnitManager.java:600) ~[spring-orm-4.3.1.RELEASE.jar!/:4.3.1.RELEASE]
    ... 31 common frames omitted

Answer 1

在不更改任何配置的情况下完成：

第 1 步：只需执行 System.out.println(new ClassPathResource("").getFile().getAbsolutePath()); 即可检查 ClassPathResource 使用的绝对路径

这个sn-p的输出会让你知道ClassPathResource所指的绝对路径是什么。

第2步：现在在上面sn-p的输出路径下创建存储上传数据的文件夹，例如：静态/图像/存储图像等。

第 3 步：现在，在创建您想要在确切位置引用的文件夹之后，按照您之前想要传递的方式传递创建的文件夹路径。

例如：

private String UploadDir = new ClassPathResource("static/image/").getFile().getAbsolutePath());

Answer 2

如果有人在运行测试时遇到这个问题，那么这就是伙计们的答案 我正在使用 Spring-boot MVC Tests-2.2.4，我遇到了同样的错误并使用 长话短说，我忘了在 webmvc 注释中添加控制器

@WebMvcTest({temp2.​​class})

这解决了问题

Answer 3

这发生在 Spring Boot 版本 1.4 中，当您的依赖项上有 Spring Data JPA jar 并且您的项目中没有使用 @entity 注释的类时。

为了解决这个问题，您可以在 pom 文件中使用 jdbc starter 而不是 jpa。

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>

Answer 4

如果它不起作用，只需将您的 SpringBoot 更新为 1.4.1.BUILD-SNAPSHOT。

同样的问题： https://github.com/spring-projects/spring-boot/issues/6314

Answer 5

@EnableAutoConfiguration(exclude = HibernateJpaAutoConfiguration.class) 必须在应用程序类上设置，并且 spring.data.jpa.repositories.enabled=false 必须在应用程序属性/yml 中设置。