内容纲要

如下代码,ComponentA类注入ComponentB类,ComponentB类注入ComponentA类,就会发生循环依赖的问题,在2.6.0之前,spring会自动处理循环依赖的问题

import org.springframework.stereotype.Service;
import javax.annotation.Resource;

@Service
public class ComponentA {

    @Resource
    private ComponentB componentB;

}
import org.springframework.stereotype.Service;
import javax.annotation.Resource;

@Service
public class ComponentB {

    @Resource
    private ComponentA componentA;

}

现在,2.6.0 这个版本已经默认禁止 Bean 之间的循环引用,如果存在循环引用就会启动失败报错:
:::info

APPLICATION FAILED TO START

Description:

The dependencies of some of the beans in the application context form a cycle:

┌─────┐
| componentA
↑ ↓
| componentB
└─────┘

Action:

Relying upon circular references is discouraged and they are prohibited by default. Update your application to remove the dependency cycle between beans. As a last resort, it may be possible to break the cycle automatically by setting spring.main.allow-circular-references to true.
:::
处理方案一:
整改业务,清理掉所有存在循环引用的 Bean
处理方案二:

spring:
  main:
    allow-circular-references: true

处理方案三:

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class SpringDemoApplication {

    public static void main(String[] args) {
        SpringApplication application = new SpringApplication(SpringDemoApplication.class);
        application.setAllowCircularReferences(Boolean.TRUE);
        application.run(args);
    }
}
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