java - 创建一个 Spring Boot 应用程序，但无法让 @autowired 工作

Question

如果我对输入文件位置进行硬编码，我就可以很好地运行和构建，但是当我尝试使用 Autowiring 来填充字段时，它就会死掉并且不会启动应用程序，因为它找不到我创建的 bean 。因此，我将向大家详细介绍我所掌握的内容，欢迎任何反馈或想法!

注意 我正在运行 springboot 版本 1.4.2，因为我正在使用 Velocity，并且此后不再支持它，因此在您查看此内容时请记住这一点。如果您需要有关我的设置的更多信息或者有任何澄清问题，请告诉我。谢谢!

好的，这是我的布局: application.yml

atb:
  #jons directory
  inputDirectory: C:/dev/git/agenttransferbatch/src/main/resources/testinputfile.txt
  #Geoff's directory
#  inputDirectoy: C:/dev/workspaces/agenttransferbatch/src/main/resources/testinputfile.txt
spring:dataSource:
    url: jdbc:db2://pmp.shelterinsurance.com
    driverClassName: com.ibm.db2.jcc.DB2Driver
    username: myusername
    password: mypassword

AppConfig.java

@Configuration
public class AppConfig
{
    @Bean
    public static PropertySourcesPlaceholderConfigurer propertyConfigIn() {
        return new PropertySourcesPlaceholderConfigurer();
    }

    @Bean
    public String getInputDirectory(@Value("${inputDirectory}") String inputDirectory)
    {
        return inputDirectory;
    }

    @Bean
    public ProcessController getProcessController()
    {
        return new ProcessController();
    }
}

ProcessController.java

@Component
public class ProcessController
{
    @Autowired
    String inputDirectory;

@PostConstruct
public void init()
{
    if(inputDirectory != null && inputDirectory.length() > 0)
    {
        processInputFile();
    }
    else
    {
        System.out.println("filePath is null or length 0");
    }
}

private void processInputFile()
{
    // code to process my input file is here, not relevant to this problem so won't bore you with it.
}

}

AgttransApplication.java

@SpringBootApplication
@Component
public class  AgttransApplication
{
    public static void main(String[] args)
    {
        SpringApplication.run(AgttransApplication.class, args);
    }
}

文件结构

src
  main
    java
      com.shelter.agttrans
        configs
          AppConfig
        dataaccessobjects
          IndividualDAO
          WholesaleDAO
        dataobjects
          TransDataObject
        services
          ProcessController
        AgttransApplication
      controllers
        templates
          XMLController
    output
    resources
      application.yml
  test
  .gitignore
  build.gradle
  gradle.properties

运行时的输出

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'processController': Injection of autowired dependencies failed; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'inputDirectory' in string value "${inputDirectory}"
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:376) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1219) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:551) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:754) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:866) ~[spring-context-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:542) ~[spring-context-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:761) [spring-boot-1.4.2.RELEASE.jar:1.4.2.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:371) [spring-boot-1.4.2.RELEASE.jar:1.4.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-1.4.2.RELEASE.jar:1.4.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1186) [spring-boot-1.4.2.RELEASE.jar:1.4.2.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1175) [spring-boot-1.4.2.RELEASE.jar:1.4.2.RELEASE]
    at com.shelter.agttrans.AgttransApplication.main(AgttransApplication.java:13) [main/:na]
Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'inputDirectory' in string value "${inputDirectory}"
    at org.springframework.util.PropertyPlaceholderHelper.parseStringValue(PropertyPlaceholderHelper.java:174) ~[spring-core-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.util.PropertyPlaceholderHelper.replacePlaceholders(PropertyPlaceholderHelper.java:126) ~[spring-core-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.core.env.AbstractPropertyResolver.doResolvePlaceholders(AbstractPropertyResolver.java:219) ~[spring-core-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.core.env.AbstractPropertyResolver.resolveRequiredPlaceholders(AbstractPropertyResolver.java:193) ~[spring-core-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.context.support.PropertySourcesPlaceholderConfigurer$2.resolveStringValue(PropertySourcesPlaceholderConfigurer.java:172) ~[spring-context-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.resolveEmbeddedValue(AbstractBeanFactory.java:813) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1079) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1059) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:835) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:741) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:467) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1128) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1022) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:512) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:482) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:207) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1131) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1059) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:589) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:370) ~[spring-beans-4.3.4.RELEASE.jar:4.3.4.RELEASE]
    ... 16 common frames omitted
FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':bootRun'.
> Process 'command 'C:\Program Files\Java\jdk1.8.0_152\bin\java.exe'' finished with non-zero exit value 1

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

BUILD FAILED

Total time: 9.061 secs
Process 'command 'C:\Program Files\Java\jdk1.8.0_152\bin\java.exe'' finished with non-zero exit value 1
10:43:28 AM: External task execution finished 'bootRun'.

Answer 1

对于字符串，您不需要定义 bean 并使用 Autowiring ，只需在字段上使用 @Value 注解即可:

@Value("${inputDirectory}")
private String inputDirectory;

而且，由于您使用的是 yaml，正如 @AHungerArtist 所说，您需要使用 ${atb.inputDirectory}