java - Spring依赖@PostConstruct

Question

假设我在 Spring @Configuration 中有这个依赖:

@Bean
public SomeClass someClass(SomeClass1 someClass1, SomeClass2 someClass2, ...) {
  return new SomeClass(someClass1, someClass2, ...);
}

假设我想在 @PostConstruct 中做一些包含 someClass 依赖的事情:

@PostConstruct
public void init() {
  someClass.doSomething();
}

这不能注入(inject):

@PostConstruct
public void init(SomeClass someClass) {
  someClass.doSomething();
}

原因:

Caused by: java.lang.IllegalStateException: Lifecycle method annotation requires a no-arg method: ...

这不能像这样在相同的配置中 Autowiring :

@Autowire
private SomeClass someClass;

@Bean
public SomeClass someClass(SomeClass1 someClass1, SomeClass2 someClass2, ...) {
  return new SomeClass(someClass1, someClass2, ...);
}

因为这导致:

Caused by: org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'globalBus': Requested bean is currently in creation: Is there an unresolvable circular reference?

一个配置可以拆分(所以 @Bean 转到另一个配置)和 @Import -ed 由这个配置，它工作正常。可能存在其他解决方案 - 例如创建一个单独的初始化 bean 左右。

有没有办法在一个@Configuration中做到这一点？

编辑

应@SotiriosDelimanolis 的要求，sscce对于使用 @Autowired 时的异常:

public class ConfigPostConstructDependenciesPrb {
   public static void main(String[] args) {
      AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(Config.class);
      ctx.getBean(Service.class);
      ctx.close();
   }

   public static class Service {
      private final Dependency dependency;

      public Service(Dependency dependency) {
         this.dependency = dependency;
      }

      public void work() {
         System.out.println(dependency.getNum());
      }

      @Override
      public String toString() {
         StringBuilder sb = new StringBuilder();
         sb.append("Service [dependency=");
         sb.append(dependency);
         sb.append("]");
         return sb.toString();
      }
   }

   public static class Dependency {
      private final int num;

      public Dependency(int num) {
         this.num = num;
      }

      public int getNum() {
         return this.num;
      }

      @Override
      public String toString() {
         StringBuilder sb = new StringBuilder();
         sb.append("SomeClass1 [num=");
         sb.append(num);
         sb.append("]");
         return sb.toString();
      }
   }

   @Configuration
   public static class BaseConfig {
      @Autowired
      private Service service;

      @Bean
      public Dependency dependency() {
         return new Dependency(42);
      }

      @Bean
      public Service service(Dependency dependency) {
         return new Service(dependency);
      }

      @PostConstruct
      public void init() {
         service.work();
      }
   }

   @Configuration
   @Import(BaseConfig.class)
   public static class Config {
      @Autowired
      private Service service;
   }   
}

Answer 1

(在 Spring 4.3.6 中测试)

在您的@Configuration 中创建一个嵌套类，并将@Autowired 服务 和@PostConstruct init() 的声明放在那里:

@Configuration
public static class BaseConfig {

    //...

    @Bean
    public Service service(Dependency dependency) {
        return new Service(dependency);
    }

    @Configuration
    public static class Setup {

        @Autowired
        private Service service;

        @PostConstruct
        public void init() {
            service.work();
        }
    }
}

以下是相应更新的完整示例。

请注意，您不必添加对 BaseConfig.Setup 的显式引用(查看 Config 类之前的 @Import 注释 -它仅指 BaseConfig 本身)。

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.*;

import javax.annotation.PostConstruct;

public class ConfigPostConstructDependenciesPrb {
    public static void main(String[] args) {
        AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext(Config.class);
        ctx.getBean(Service.class);
        ctx.close();
    }

    public static class Service {
        private final Dependency dependency;

        public Service(Dependency dependency) {
            this.dependency = dependency;
        }

        public void work() {
            System.out.println(dependency.getNum());
        }

        @Override
        public String toString() {
            StringBuilder sb = new StringBuilder();
            sb.append("Service [dependency=");
            sb.append(dependency);
            sb.append("]");
            return sb.toString();
        }
    }

    public static class Dependency {
        private final int num;

        public Dependency(int num) {
            this.num = num;
        }

        public int getNum() {
            return this.num;
        }

        @Override
        public String toString() {
            StringBuilder sb = new StringBuilder();
            sb.append("SomeClass1 [num=");
            sb.append(num);
            sb.append("]");
            return sb.toString();
        }
    }

    @Configuration
    public static class BaseConfig {
        @Bean
        public Dependency dependency() {
            return new Dependency(42);
        }

        @Bean
        public Service service(Dependency dependency) {
            return new Service(dependency);
        }

        @Configuration
        public static class Setup {
            @Autowired
            private Service service;

            @PostConstruct
            public void init() {
                service.work();
            }
        }
    }

    @Configuration
    @Import(BaseConfig.class)
    public static class Config {
        @Autowired
        private Service service;
    }
}