springboot 循环依赖示例

本是古典何须时尚 2023-02-21 12:46 14阅读 0赞

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### springboot 循环依赖示例 ###

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**循环依赖解决**

**尽量不要使用循环依赖；**

当无可避免要使用循环依赖时，**禁止使用构造器注入依赖属性，使用注解（@Resource、@Autowired）属性**

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**自循环依赖：属性注入**

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**pojo 层**

**Person**

@Component
    public class Person {
    
        @Resource
        private Person person;
    
        public void print(){
            System.out.println(this.person);
        }
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**controller 层**

**HelloController**

@RestController
    public class HelloController {
    
        @Resource
        private Person person;
    
        @RequestMapping("/hello")
        public String hello(){
            person.print();
    
            return "success";
        }
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**控制台输出**

2020-07-03 18:20:11.260  INFO 13544 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
    2020-07-03 18:20:11.266  INFO 13544 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 6 ms
    com.example.demo.pojo.Person@2b26c8e4

**使用三级缓存，解决了属性注入自循环依赖**

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**自循环依赖：构造器注入**

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**pojo 层**

**Person**

@Component
    public class Person {
    
        private Person person;
    
        public Person(Person person){
            this.person=person;
        }
    
        public void print(){
            System.out.println(this.person);
        }
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**controller 层**

**HelloController**

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**控制台输出**

2020-07-03 18:24:33.550  INFO 19416 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
    2020-07-03 18:24:33.668  INFO 19416 --- [           main] ConditionEvaluationReportLoggingListener : 
    
    Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
    2020-07-03 18:24:33.674 ERROR 19416 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 
    
    ***************************
    APPLICATION FAILED TO START
    ***************************
    
    Description:
    
    The dependencies of some of the beans in the application context form a cycle:
    
       helloController
    ┌─────┐
    |  person defined in file [E:\java\IdeaProjects\springboot 测试\target\classes\com\example\demo\pojo\Person.class]
    └─────┘

**启动报错：存在自循环依赖，使用构造器创建person，person没有添加到缓存，不能提前暴露**

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**自循环依赖：代理对象（@Transactional）**

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**service 层**

**HelloService**

public interface HelloService {
    
        void hello();
    }

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**serviceImpl 层**

**HelloServiceImpl**

@Service
    public class HelloServiceImpl implements HelloService {
    
        @Resource
        private HelloService helloService;
    
        @Override
        @Transactional
        public void hello() {
            System.out.println(helloService);
            System.out.println("hello world");
        }
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**controller 层**

**HelloController**

@RestController
    public class HelloController {
    
        @Resource
        private HelloService helloService;
    
        @RequestMapping("/hello")
        public String hello(){
            helloService.hello();
    
            return "success";
        }
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**控制台输出**

**localhost:8080/hello**

2020-07-03 19:09:09.017  INFO 3652 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring DispatcherServlet 'dispatcherServlet'
    2020-07-03 19:09:09.017  INFO 3652 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Initializing Servlet 'dispatcherServlet'
    2020-07-03 19:09:09.023  INFO 3652 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet        : Completed initialization in 6 ms
    WARNING: An illegal reflective access operation has occurred
    WARNING: Illegal reflective access by org.springframework.cglib.core.ReflectUtils (file:/E:/Program%20Files/apache-maven-3.6.1-bin/apache-maven-3.6.1/repository/org/springframework/spring-core/5.2.7.RELEASE/spring-core-5.2.7.RELEASE.jar) to method java.lang.ClassLoader.defineClass(java.lang.String,byte[],int,int,java.security.ProtectionDomain)
    WARNING: Please consider reporting this to the maintainers of org.springframework.cglib.core.ReflectUtils
    WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
    WARNING: All illegal access operations will be denied in a future release
    com.example.demo.serviceImpl.HelloServiceImpl@4aa55ed8
    hello world

**说明：事务Transactional可以提前暴露，可将代理对象提前注入到其他bean中**

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**自循环依赖：代理对象（@Async）**

## ##

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**service 层**

## ##

**Hello3Service**

@Service
    public class Hello3Service {
    
        @Resource
        private Hello3Service hello3Service;
    
        @Async
        public void test(){
            hello3Service.test2();
            System.out.println("hello3 service test");
        }
    
        @Async
        public void test2(){
            System.out.println("hello3 service test2");
        }
    }

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**config 层**

**WebConfig：开启异步功能**

@EnableAsync
    @Configuration
    public class WebConfig {
    }

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**controller 层**

## ##

**Hello2Controller**

@RestController
    public class Hello2Controller {
    
        @Resource
        private Hello3Service hello3Service;
    
        @RequestMapping("/hello2")
        public String hello(){
            hello3Service.test();
    
            return "success";
        }
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**控制台输出**

2020-07-04 16:03:15.238  INFO 3036 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
    2020-07-04 16:03:15.238  INFO 3036 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1165 ms
    2020-07-04 16:03:15.325  WARN 3036 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'hello2Controller': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'hello3Service': Bean with name 'hello3Service' has been injected into other beans [hello3Service] in its raw version as part of a circular reference, but has eventually been wrapped. This means that said other beans do not use the final version of the bean. This is often the result of over-eager type matching - consider using 'getBeanNamesForType' with the 'allowEagerInit' flag turned off, for example.
    2020-07-04 16:03:15.329  INFO 3036 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
    2020-07-04 16:03:15.350  INFO 3036 --- [           main] ConditionEvaluationReportLoggingListener : 
    
    Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
    2020-07-04 16:03:15.369 ERROR 3036 --- [           main] o.s.boot.SpringApplication               : Application run failed
    
    org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'hello2Controller': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'hello3Service': Bean with name 'hello3Service' has been injected into other beans [hello3Service] in its raw version as part of a circular reference, but has eventually been wrapped. This means that said other beans do not use the final version of the bean. This is often the result of over-eager type matching - consider using 'getBeanNamesForType' with the 'allowEagerInit' flag turned off, for example.
    	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:321) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1422) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:594) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:893) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:879) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:551) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:143) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:758) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    	at com.example.demo.DemoApplication.main(DemoApplication.java:10) ~[classes/:na]
    Caused by: org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'hello3Service': Bean with name 'hello3Service' has been injected into other beans [hello3Service] in its raw version as part of a circular reference, but has eventually been wrapped. This means that said other beans do not use the final version of the bean. This is often the result of over-eager type matching - consider using 'getBeanNamesForType' with the 'allowEagerInit' flag turned off, for example.
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:624) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:207) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveBeanByName(AbstractAutowireCapableBeanFactory.java:454) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:527) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:497) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:650) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:239) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:130) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:318) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	... 18 common frames omitted

**启动报错：将未创建完成的对象注入到bean中，async不支持早期引用时创建代理对象**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80MzkzMTYyNQ_size_16_color_FFFFFF_t_70][]

### \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* ###

**循环依赖：代理对象（@Async）**

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**service 层**

**HelloService**

@Service
    public class HelloService {
    
        @Resource
        private Hello2Service hello2Service;
    
        @Async
        public void test(){
            hello2Service.test2();
            System.out.println("hello service test");
        }
    
        @Async
        public void test2(){
            System.out.println("hello service test2");
        }
    }

**Hello2Servcice**

@Service
    public class Hello2Service {
    
        @Resource
        private HelloService helloService;
    
        @Async
        public void test(){
            helloService.test2();
            System.out.println("hello2 service test");
        }
    
        @Async
        public void test2(){
            System.out.println("hello2 service test2");
        }
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**config 层**

**WebConfig：开启异步功能**

@EnableAsync
    @Configuration
    public class WebConfig {
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**controller 层**

**HelloController**

@RestController
    public class HelloController {
    
        @Resource
        private HelloService helloService;
    
        @Resource
        private Hello2Service hello2Service;
    
        @RequestMapping("/hello")
        public String hello(){
            helloService.test();
            hello2Service.test();
    
            return "success";
        }
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**控制台输出**

2020-07-04 11:47:53.826  INFO 10168 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
    2020-07-04 11:47:53.826  INFO 10168 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 941 ms
    2020-07-04 11:47:53.900  WARN 10168 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'helloController': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'helloService': Bean with name 'helloService' has been injected into other beans [hello2Service] in its raw version as part of a circular reference, but has eventually been wrapped. This means that said other beans do not use the final version of the bean. This is often the result of over-eager type matching - consider using 'getBeanNamesForType' with the 'allowEagerInit' flag turned off, for example.
    2020-07-04 11:47:53.903  INFO 10168 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
    2020-07-04 11:47:53.917  INFO 10168 --- [           main] ConditionEvaluationReportLoggingListener : 
    
    Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
    2020-07-04 11:47:53.931 ERROR 10168 --- [           main] o.s.boot.SpringApplication               : Application run failed
    
    org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'helloController': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'helloService': Bean with name 'helloService' has been injected into other beans [hello2Service] in its raw version as part of a circular reference, but has eventually been wrapped. This means that said other beans do not use the final version of the bean. This is often the result of over-eager type matching - consider using 'getBeanNamesForType' with the 'allowEagerInit' flag turned off, for example.
    	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:321) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1422) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:594) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:893) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:879) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:551) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:143) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:758) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) ~[spring-boot-2.3.1.RELEASE.jar:2.3.1.RELEASE]
    	at com.example.demo.DemoApplication.main(DemoApplication.java:10) ~[classes/:na]
    Caused by: org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'helloService': Bean with name 'helloService' has been injected into other beans [hello2Service] in its raw version as part of a circular reference, but has eventually been wrapped. This means that said other beans do not use the final version of the bean. This is often the result of over-eager type matching - consider using 'getBeanNamesForType' with the 'allowEagerInit' flag turned off, for example.
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:624) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:207) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.resolveBeanByName(AbstractAutowireCapableBeanFactory.java:454) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.autowireResource(CommonAnnotationBeanPostProcessor.java:527) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.getResource(CommonAnnotationBeanPostProcessor.java:497) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor$ResourceElement.getResourceToInject(CommonAnnotationBeanPostProcessor.java:650) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.annotation.InjectionMetadata$InjectedElement.inject(InjectionMetadata.java:239) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:130) ~[spring-beans-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	at org.springframework.context.annotation.CommonAnnotationBeanPostProcessor.postProcessProperties(CommonAnnotationBeanPostProcessor.java:318) ~[spring-context-5.2.7.RELEASE.jar:5.2.7.RELEASE]
    	... 18 common frames omitted

**启动报错：****将未创建完成的对象当做代理对象注入，async不支持在获取早期引用的时候创建代理对象**

### \*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\* ###

**原型（prototype）循环依赖**

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**pojo 层**

**A**

@Scope("prototype")
    @Component
    public class A {
    
        @Resource
        private B b;
    
        public void print(){
            System.out.println(b);
        }
    }

**B**

@Scope("prototype")
    @Component
    public class B {
    
        @Resource
        private A a;
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**controller 层**

**HelloController**

@RestController
    public class HelloController {
    
        @Resource
        private A a;
    
        @RequestMapping("/hello")
        public String hello(){
            a.print();
    
            return "success";
        }
    }

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**控制台输出**

**localhost:8080/hello**

2020-07-03 21:36:56.726  INFO 21076 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
    2020-07-03 21:36:56.726  INFO 21076 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1039 ms
    2020-07-03 21:36:56.780  WARN 21076 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'helloController': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'a': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'b': Injection of resource dependencies failed; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'a': Requested bean is currently in creation: Is there an unresolvable circular reference?
    2020-07-03 21:36:56.781  INFO 21076 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
    2020-07-03 21:36:56.795  INFO 21076 --- [           main] ConditionEvaluationReportLoggingListener : 
    
    Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
    2020-07-03 21:36:56.799 ERROR 21076 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 
    
    ***************************
    APPLICATION FAILED TO START
    ***************************
    
    Description:
    
    The dependencies of some of the beans in the application context form a cycle:
    
       helloController
    ┌─────┐
    |  a
    ↑     ↓
    |  b
    └─────┘

**prototype没有使用三级缓存，不能解决对象之间的循环依赖**

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