未在Scala Spring Boot项目中工作

Question

考虑到下面的示例，我尝试在SampleStarter中使用SampleStarter配置bean来使用正确填充的bean启动服务。.scala文件以SampleStarter.scala作为名称，在该文件中定义了Sample。

@SpringBootApplication
@Service
object SampleStarter {

  @(Autowired @setter)
  var sample: Sample = _ // always null, @Autowired not working?

  def getInstance() = this

  def main(args: Array[String]): Unit = {
    SpringApplication.run(classOf[Sample], args: _*)

    sample.run()
  }

}

@Configuration
@ConfigurationProperties("sample")
@EnableConfigurationProperties
class Sample {

  @BeanProperty
  var myProperty: String = _

  def run(): Unit = { // bean config seems OK, when debugging with @PostConstruct the 'myProperty' value is filled properly
    print(myProperty)
  }

}

每当我在sample.run()之后点击SpringApplication.run(classOf[Sample], args: _*)，sample属性总是为null。我认为这与Scala中的object有关，因为它们的所有成员都是静态的。我把这个问题看作是对How to use Spring Autowired (or manually wired) in Scala object?的启发，但仍然无法使我的代码工作。

我实例化类的方式有问题吗?还是与Scala有关？

编辑

按照@Rob的回答，这就是我试图复制他的解决方案的方法。

@SpringBootApplication
@Service
object SampleStarter {

  @(Autowired @setter)
  var sample: Sample = _

  def getInstance() = this

  def main(args: Array[String]): Unit = {
    SpringApplication.run(classOf[Sample], args: _*)

    sample.run()
  }

}


@Configuration // declares this class a source of beans
@ConfigurationProperties("sample") // picks up from various config locations
@EnableConfigurationProperties // not certain this is necessary
class AppConfiguration {

  @BeanProperty
  var myProperty: String = _

  @Bean
  // Error -> Parameter 0 of constructor in myproject.impl.Sample required a bean of type 'java.lang.String' that could not be found.
  def sample: Sample = new Sample(myProperty)

}

class Sample(@BeanProperty var myProperty: String) {

  def run(): Unit = {
    print(myProperty)
  }

}

Answer 1

@Configuration声明了一个能够提供@Bean的源文件，这不是您想要的。您希望/需要将示例作为POJO类(POSO?)然后让另一个类"AppConfiguration“(比方说)加上@Configuration注释，以创建一个类型为Sample的@Bean

我的scala非常生疏，所以这可能根本不编译，但是结构应该大致正确。

@Configuration // declares this class a source of beans
@ConfigurationProperties("sample") // picks up from various config locations
@EnableConfigurationProperties // not certain this is necessary
class AppConfiguration {

  @Bean
  def getSample(@BeanProperty myProperty: String): Sample = new Sample(myProperty)

}

class Sample {

  var myProperty: String

  def Sample(property : String) = {
    this.myProperty = myProperty
  }

  def run(): Unit = {
    print(myProperty)
  }
}

现在您有了一个Sample类作为@Bean，它可以在任何需要的地方都是@Autowired。

@SpringBootApplication
@Service
object SampleStarter {

  // note its typically better to inject variables into a constructor
  // rather than directly into fields as the behaviour is more predictable
  @Autowired
  var sample: Sample

  def getInstance() = this // not required ??

  def main(args: Array[String]): Unit = {
    SpringApplication.run(classOf[Sample], args: _*)

    sample.run()
  }
}

FWIW，您可以独立启动SpringBoot应用程序，并具有完全独立的@Service逻辑。@Service是另一种类型的@Bean，可供SpringBootApplication的其他部分使用。