错误创建bean-在Service中注入配置类不起作用

Question

我尝试像本教程中那样实现REST服务：Tutorial

但是我遇到了这个错误：

Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'fileStorageService' defined in file: Bean instantiation via constructor failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.airgnb.service.FileStorageService]: Constructor threw exception; nested exception is java.lang.NullPointerException
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.airgnb.service.FileStorageService]: Constructor threw exception; nested exception is java.lang.NullPointerException
Caused by: java.lang.NullPointerException

服务等级：

@Service
public class FileStorageService {

    private final Path fileStorageLocation;

    @Autowired
    public FileStorageService(FileStorageProperties fileStorageProperties) {
        this.fileStorageLocation = Paths.get(fileStorageProperties.getUploadDir())
            .toAbsolutePath().normalize();

        try {
            Files.createDirectories(this.fileStorageLocation);
        } catch (Exception ex) {
            throw new FileStorageServiceException("Could not create the directory where the uploaded files will be stored.", ex);
        }
    }
}

配置类：

@Configuration
@ConfigurationProperties(prefix = "file")
public class FileStorageProperties {

    private String uploadDir;

    public String getUploadDir() {
        return uploadDir;
    }

    public void setUploadDir(String uploadDir) {
        this.uploadDir = uploadDir;
    }
}

该应用程序也这样注释：

@SpringBootApplication
@EnableConfigurationProperties({FileStorageProperties.class})
public class TestApp implements InitializingBean {

我认为唯一的不同是，我使用application.yml而不是application.properties，但是我定义的属性与本教程类似，只是以yml样式。

我不知道为什么不注入FileStorageProperties，因此无法创建FileStorageService。

我已经尝试用@Import(FileStoroageProperties.class)以及其他一些依赖项注入方式（例如字段注入）为应用程序添加注释。

Answer 1

我不认为没有注入FileStorageProperties。该错误将指示未找到类型为FileStorageProperties的Bean。您只需在构造函数中有一个NullPointerException。

我认为fileStorageProperties.getUploadDir()返回了null。