在Spring Boot中配置PropertyPlaceholderConfigurer

Question

我有一個Spring Boot應用程序，我在其中傳遞屬性源，例如：

@PropertySource({"classpath:application.properties","file:C:/MyFolder/project.properties"})

一切都完美連接。 但是，當我嘗試以編程方式執行以下操作時：

@Bean
public PropertyPlaceholderConfigurer properties() throws URISyntaxException {
  PropertyPlaceholderConfigurer proprty =  new PropertyPlaceholderConfigurer();
  proprty.setLocations(new Resource[] {
                                        new ClassPathResource("application.properties"),
                                        new FileSystemResource("C:/MyFolder/project.properties")});
  return proprty;
}

沒用 它找不到C:/MyFolder/project.properties定義的屬性。 有任何想法嗎？

我得到的堆棧跟蹤是

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.boot.autoconfigure.orm.jpa.HibernateJpaAutoConfiguration': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private javax.sql.DataSource org.springframework.boot.autoconfigure.orm.jpa.JpaBaseConfiguration.dataSource; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [org/springframework/boot/autoconfigure/jdbc/DataSourceAutoConfiguration$NonEmbeddedConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'dataSource' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Cannot determine embedded database driver class for database type NONE. If you want an embedded database please put a supported one on the classpath.
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:334)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1202)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:368)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1111)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1006)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:504)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:956)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:747)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:480)
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:118)
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:686)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:320)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:957)
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:946)
    at com.utilisoft.backfill.Application.main(Application.java:108)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private javax.sql.DataSource org.springframework.boot.autoconfigure.orm.jpa.JpaBaseConfiguration.dataSource; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [org/springframework/boot/autoconfigure/jdbc/DataSourceAutoConfiguration$NonEmbeddedConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'dataSource' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Cannot determine embedded database driver class for database type NONE. If you want an embedded database please put a supported one on the classpath.
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:561)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:331)
    ... 25 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'dataSource' defined in class path resource [org/springframework/boot/autoconfigure/jdbc/DataSourceAutoConfiguration$NonEmbeddedConfiguration.class]: Bean instantiation via factory method failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'dataSource' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Cannot determine embedded database driver class for database type NONE. If you want an embedded database please put a supported one on the classpath.
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:599)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1111)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1006)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:504)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:476)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:303)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:299)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1120)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1044)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:942)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:533)
    ... 27 more
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [javax.sql.DataSource]: Factory method 'dataSource' threw exception; nested exception is org.springframework.beans.factory.BeanCreationException: Cannot determine embedded database driver class for database type NONE. If you want an embedded database please put a supported one on the classpath.
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:189)
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:588)
    ... 39 more
Caused by: org.springframework.beans.factory.BeanCreationException: Cannot determine embedded database driver class for database type NONE. If you want an embedded database please put a supported one on the classpath.
    at org.springframework.boot.autoconfigure.jdbc.DataSourceProperties.getDriverClassName(DataSourceProperties.java:137)
    at org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration$NonEmbeddedConfiguration.dataSource(DataSourceAutoConfiguration.java:117)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:162)

顯然，我無法確定數據庫設置。 它們在project.properties文件中定義，當我以編程方式設置屬性時，該文件不會連接。

Answer 1

您遇到了生命周期問題……您正在使用尚未設置的屬性（如您所知）創建一個bean。 用@PostConstruct注釋的方法初始化數據庫。 有關初始化回調，請參見本段。 簡而言之，它表示InitializingBean接口：

...允許容器在容器上設置了所有必需的屬性后，bean可以執行初始化工作。

然后繼續說使用@PostConstruct而不是InitializingBean接口，這樣您的代碼就不必不必要地耦合到Spring了。

Answer 2

如果檢查DatasourceProperties.java 代碼 ，將看到使用ConfigurationProperties批注綁定了配置。 配置外部化文檔中記錄了此批注的處理。 所提到的解決步驟均不依賴於您提供的實現。

Answer 3

我認為您可以從Spring docs中完全實現所需的功能，而無需注釋或以編程方式對其進行定義：

Spring Boot使用一個非常特殊的PropertySource順序，該順序旨在允許合理地覆蓋值，按以下順序考慮屬性：

1. 命令行參數。
2. 來自SPRING_APPLICATION_JSON的屬性（嵌入在環境變量或系統屬性中的內聯JSON）
3. 來自Java：comp / env的JNDI屬性。
4. Java系統屬性（System.getProperties（））。
5. 操作系統環境變量。
6. 一個RandomValuePropertySource，僅具有random。*屬性。
7. 打包的jar之外的特定於配置文件的應用程序屬性（application- {profile} .properties和YAML變體）
8. 打包在jar中的特定於配置文件的應用程序屬性（application- {profile} .properties和YAML變體）
9. 打包的jar之外的應用程序屬性（application.properties和YAML變體）。
10. 打包在jar中的應用程序屬性（application.properties和YAML變體）。
11. @Configuration類上的@PropertySource批注。
12. 默認屬性（使用SpringApplication.setDefaultProperties指定）。

換句話說，如果您在src/main/resources有一個application.properties文件用於開發（上面的第10點），而在jar文件旁邊有一個外部文件用於生產（上面的第9點），則將選擇正確的屬性。自動上升。