java 在 Spring Boot 中配置 PropertyPlaceholderConfigurer

Configure PropertyPlaceholderConfigurer in Spring Boot

提问by george

I have a Spring Bootapplication where I pass in the property sources like:

我有一个Spring Boot应用程序，我在其中传递了属性源，例如：

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

And everything gets wired perfectly. However, when I attempt to do the same programatically like:

一切都完美连接。但是，当我尝试以编程方式执行相同操作时：

@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;
}

It doesn't work. It cannot find the properties defined in C:/MyFolder/project.properties. Any ideas?

它不起作用。它找不到 中定义的属性C:/MyFolder/project.properties。有任何想法吗？

The stacktrace I am getting is

我得到的堆栈跟踪是

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.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.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.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)

Obviously I cannot determine the database settings. They are defined in project.propertiesfile which doesn't get wired when I programatically set up the properties.

显然我无法确定数据库设置。它们在project.properties文件中定义，当我以编程方式设置属性时，该文件不会被连接。

回答by Paul

You've got a lifecycle problem...you're creating a bean with properties that aren't yet set (as you know). Initialize your database in a method annotated with @PostConstruct. See this paragraph on initialization callbacks. In short it says the InitializingBeaninterface:

您遇到了生命周期问题……您正在创建一个属性尚未设置的 bean（如您所知）。用注释的方法初始化您的数据库@PostConstruct。请参阅有关初始化回调的段落。简而言之，它说InitializingBean界面：

...allows a bean to perform initialization work after all necessary properties on the bean have been set by the container.

...允许 bean 在容器设置了 bean 的所有必要属性后执行初始化工作。

It then goes on to say to use @PostConstructinstead of the InitializingBeaninterface so your code isn't unnecessarily coupled to Spring.

然后继续说使用@PostConstruct而不是InitializingBean接口，因此您的代码不会不必要地耦合到 Spring。

回答by Guy Bouallet

If you check DatasourceProperties.java code, you will see that configuration is bound using a ConfigurationProperties annotation. The processing of this annotation is documented in configuration externalization documentation. None of the mentioned resolution steps rely on the implementation you provided.

如果您检查 DatasourceProperties.java代码，您将看到配置是使用 ConfigurationProperties 注释绑定的。此注释的处理记录在配置外部化文档中。上述解决步骤均不依赖于您提供的实现。

回答by DaveyDaveDave

I think you can achieve exactly what you're looking for without either the annotation or defining it programmatically, from the Spring docs:

我认为您可以在没有注释或以编程方式定义它的情况下实现您正在寻找的内容，来自Spring 文档：

Spring Boot uses a very particular PropertySource order that is designed to allow sensible overriding of values, properties are considered in the following order:

1. Command line arguments.
2. Properties from SPRING_APPLICATION_JSON (inline JSON embedded in an environment variable or system property)
3. JNDI attributes from java:comp/env.
4. Java System properties (System.getProperties()).
5. OS environment variables.
6. A RandomValuePropertySource that only has properties in random.*.
7. Profile-specific application properties outside of your packaged jar (application-{profile}.properties and YAML variants)
8. Profile-specific application properties packaged inside your jar (application-{profile}.properties and YAML variants)
9. Application properties outside of your packaged jar (application.properties and YAML variants).
10. Application properties packaged inside your jar (application.properties and YAML variants).
11. @PropertySource annotations on your @Configuration classes.
12. Default properties (specified using SpringApplication.setDefaultProperties).

Spring Boot 使用了一个非常特殊的 PropertySource 顺序，该顺序旨在允许合理覆盖值，属性按以下顺序考虑：

1. 命令行参数。
2. 来自 SPRING_APPLICATION_JSON 的属性（嵌入在环境变量或系统属性中的内联 JSON）
3. 来自 java:comp/env 的 JNDI 属性。
4. Java 系统属性 (System.getProperties())。
5. 操作系统环境变量。
6. 仅在 random.* 中具有属性的 RandomValuePropertySource。
7. 打包 jar 之外的特定于配置文件的应用程序属性（application-{profile}.properties 和 YAML 变体）
8. 打包在 jar 中的特定于配置文件的应用程序属性（application-{profile}.properties 和 YAML 变体）
9. 打包 jar 之外的应用程序属性（application.properties 和 YAML 变体）。
10. 打包在 jar 中的应用程序属性（application.properties 和 YAML 变体）。
11. @Configuration 类上的 @PropertySource 注释。
12. 默认属性（使用 SpringApplication.setDefaultProperties 指定）。

In other words, if you have an application.propertiesfile in your src/main/resourcesfor development (point 10 above), and an external one next to your jarfile for production (point 9 above), the correct properties will be picked up automatically.

换句话说，如果您有一个用于开发的application.properties文件src/main/resources（上面的第 10 点），并且在您的jar文件旁边有一个用于生产的外部文件（上面的第 9 点），将自动选择正确的属性。