Question

当使用spring注释@Bean声明一些实例时，参数是注入的，这些是必需的，如果找不到实例，将抛出NoSuchBeanException。

如何让它可选？像@Autowired(required = false)

这样的东西

例如

@Configuration
class SomeConfiguration {

  @Bean
  public SomeComponent someComponent(Depend1 depend1,
                                     Depend2 depend2) {
    SomeComponent someComponent = new SomeComponent();
    someComponent.setDepend1(depend1);
    if (depend2 != null) {
      someComponent.setDepend2(depend2);
    }
    return someComponent;
  }
}

Answer 1

只需使用Optional：

@Bean
public SomeComponent someComponent(Depend1 depend1, Optional<Depend2> depend2) {
   ...
}

Answer 2

您可以在参数上使用@Autowired(required = false)：

@Configuration
class SomeConfiguration {

  @Bean
  public SomeComponent someComponent(Depend1 depend1,
                                     @Autowired(required = false) Depend2 depend2) {
    SomeComponent someComponent = new SomeComponent();
    someComponent.setDepend1(depend1);
    if (depend2 != null) {
      someComponent.setDepend2(depend2);
    }
    return someComponent;
  }
}

Answer 3

或者你可以像这样定义多个配置文件

@Configuration
@Profile("dev")
class DevConfiguration {

  @Bean
  public SomeComponent someComponent(Depend1 depend1) {
    SomeComponent someComponent = new SomeComponent();
    someComponent.setDepend1(depend1);
    return someComponent;
  }
}

和

@Configuration
@Profile("prod")
class ProdConfiguration {

  @Bean
  public SomeComponent someComponent(Depend1 depend1, Depend2 depend2) {
    SomeComponent someComponent = new SomeComponent();
    someComponent.setDepend1(depend1);
    someComponent.setDepend2(depend2);
    return someComponent;
  }
}

当您现在使用命令行参数-Dspring.profiles.active="dev"或-Dspring.profiles.active="prod"启动应用程序时，它将为您选择正确的bean。如果多个配置文件（例如test和dev）需要相同的实现，您只需将@Profile("dev")替换为@Profile({"dev","test"})

如何在Spring中的@Bean方法中定义可选参数（依赖项）？

3 个答案: