springboot循环依赖问题,spring解决依赖循环

简介

说明

　　本文介绍弹簧的循环依赖什么时候会出现以及如何解决循环依赖。

　　循环依赖场景

　　1.单例领域的循环依赖（采用三级缓存提前暴露对象的方法解决)

　　2.构造器的循环依赖（无法解决循环依赖问题)

　　3.多例领域的循环依赖（无法解决循环依赖问题)

　　对于多例的豆子，春天不缓存"原型"作用域的豆子，不提前暴露一个创建中的豆子。

问题复现

公共代码

　　包com。举例。控制器；导入com。举例。tmp。a；导入org。spring框架。豆子。工厂。注释。自动连线；导入org。spring框架。网络。绑定。注释。获取映射；导入org。spring框架。网络。绑定。注释。休息控制器；@ RestControllerpublic class hello controller { @ auto wired A A；@GetMapping(/test1 )公共字符串test1(){ return a . gettest()；}}

1.构造器注入

代码

　　包com。举例。tmp导入org。spring框架。刻板印象。组件；@组件公共类A {//@自动连线私有B B公A(B B){这个。B=B}私有字符串名称=托尼公共字符串getName(){ return name；} public void set name(String name){ this。name=名称；}公共字符串getTest() { return b.getAge().toString()名称；} }包com。举例。tmp导入org。spring框架。刻板印象。组件；@组件公共类B {//@自动连线私有A A公B(A A){这个。A=A}私人整数年龄=20;public Integer getAge(){ return age；} public void setAge(整数年龄){这个。年龄=年龄；}}测试

　　启动结果。____ _ __ _ _/\/____ __ _ _(_)_ __ __ _ (()___ _ _ _ /_` \/___) _) (_ ) ) ) ) ____ ._ _ _ _ _ _ _ _，////============ _ ============= _ _ _ _ _ _/=/_/_/_/_/: Spring Boot :(v 2 .3 .0 .发布)2021-04-03 10:40:18.732信息5872-【主】com。举例。演示应用程序：开始演示

　　workIdea_projdemo_JAVAdemo_SpringBoot)2021-04-03 10:40:18.748 INFO 5872 --- [ main] com.example.DemoApplication : No active profile set, falling back to default profiles: default2021-04-03 10:40:20.904 INFO 5872 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)2021-04-03 10:40:20.920 INFO 5872 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]2021-04-03 10:40:20.920 INFO 5872 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.35]2021-04-03 10:40:20.998 INFO 5872 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext2021-04-03 10:40:20.998 INFO 5872 --- [ main] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 2219 ms2021-04-03 10:40:24.436 WARN 5872 --- [ main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'helloController': Unsatisfied dependency expressed through field 'a'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'a' defined in file [E:workIdea_projdemo_JAVAdemo_SpringBoottargetclassescomexampletmpA.class]: Unsatisfied dependency expressed through constructor parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'b' defined in file [E:workIdea_projdemo_JAVAdemo_SpringBoottargetclassescomexampletmpB.class]: Unsatisfied dependency expressed through constructor parameter 0; 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?2021-04-03 10:40:24.451 INFO 5872 --- [ main] o.apache.catalina.core.StandardService : Stopping service [Tomcat]2021-04-03 10:40:24.451 INFO 5872 --- [ main] ConditionEvaluationReportLoggingListener :Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.2021-04-03 10:40:24.467 ERROR 5872 --- [ 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 (field com.example.tmp.A com.example.controller.HelloController.a)┌─────┐ a defined in file [E:workIdea_projdemo_JAVAdemo_SpringBoottargetclassescomexampletmpA.class]↑ ↓ b defined in file [E:workIdea_projdemo_JAVAdemo_SpringBoottargetclassescomexampletmpB.class]└─────┘2021-04-03 10:40:24.467 WARN 5872 --- [ main] o.s.boot.SpringApplication : Unable to close ApplicationContextorg.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'springApplicationAdminRegistrar' defined in class path resource [org/springframework/boot/autoconfigure/admin/SpringApplicationAdminJmxAutoConfiguration.class]: Unsatisfied dependency expressed through method 'springApplicationAdminRegistrar' parameter 1; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.core.env.Environment' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {} at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:798) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:539) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:207) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.context.event.AbstractApplicationEventMulticaster.retrieveApplicationListeners(AbstractApplicationEventMulticaster.java:245) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.context.event.AbstractApplicationEventMulticaster.getApplicationListeners(AbstractApplicationEventMulticaster.java:197) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:134) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:403) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:360) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.boot.availability.AvailabilityChangeEvent.publish(AvailabilityChangeEvent.java:81) ~[spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE] at org.springframework.boot.availability.AvailabilityChangeEvent.publish(AvailabilityChangeEvent.java:67) ~[spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.doClose(ServletWebServerApplicationContext.java:167) ~[spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE] at org.springframework.context.support.AbstractApplicationContext.close(AbstractApplicationContext.java:978) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.boot.SpringApplication.handleRunFailure(SpringApplication.java:814) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:325) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE] at com.example.DemoApplication.main(DemoApplication.java:10) [classes/:na]Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.core.env.Environment' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {} at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1716) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1272) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1226) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:885) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:789) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] ... 23 common frames omitted

2.Feild注入多例（@AutoWired）

本处将A类设置为多例，将B类设置为单例。（其实，都设为多例或者A类设置为单例，B类设置为多例都是一样的，都会报循环依赖错误）

　　代码

package com.example.tmp; import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.config.ConfigurableBeanFactory;import org.springframework.context.annotation.Scope;import org.springframework.stereotype.Component; @Component@Scope(ConfigurableBeanFactory.SCOPE_PROTOTYPE)public class A { @Autowired private B b; private String name = "Tony"; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getTest() { return b.getAge().toString() + name; }}

package com.example.tmp; import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Component; @Componentpublic class B { @Autowired private A a; private Integer age = 20; public Integer getAge() { return age; } public void setAge(Integer age) { this.age = age; }}

测试

　　启动结果

. ____ _ __ _ _/\ / ___'_ __ _ _(_)_ __ __ _ ( ( )___ '_ '_ '_ / _` \/ ___) _) (_ ) ) ) ) ' ____ .___ __ ___, / / / /=========_==============___/=/_/_/_/:: Spring Boot :: (v2.3.0.RELEASE)2021-04-03 11:09:09.781 INFO 12048 --- [ main] com.example.DemoApplication : Starting DemoApplication on DESKTOP-QI6B9ME with PID 12048 (E:workIdea_projdemo_JAVAdemo_SpringBoottargetclasses started by Liu in E:workIdea_projdemo_JAVAdemo_SpringBoot)2021-04-03 11:09:09.783 INFO 12048 --- [ main] com.example.DemoApplication : No active profile set, falling back to default profiles: default2021-04-03 11:09:10.555 INFO 12048 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)2021-04-03 11:09:10.562 INFO 12048 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]2021-04-03 11:09:10.562 INFO 12048 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.35]2021-04-03 11:09:10.650 INFO 12048 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext2021-04-03 11:09:10.650 INFO 12048 --- [ main] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 822 ms2021-04-03 11:09:10.698 WARN 12048 --- [ main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'helloController': Unsatisfied dependency expressed through field 'a'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'a': Unsatisfied dependency expressed through field 'b'; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'b': Unsatisfied dependency expressed through field 'a'; 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?2021-04-03 11:09:10.700 INFO 12048 --- [ main] o.apache.catalina.core.StandardService : Stopping service [Tomcat]2021-04-03 11:09:10.710 INFO 12048 --- [ main] ConditionEvaluationReportLoggingListener :Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.2021-04-03 11:09:10.712 ERROR 12048 --- [ 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 (field com.example.tmp.A com.example.controller.HelloController.a)┌─────┐ a (field com.example.tmp.B com.example.tmp.A.b)↑ ↓ b (field com.example.tmp.A com.example.tmp.B.a)└─────┘2021-04-03 11:09:10.717 WARN 12048 --- [ main] o.s.boot.SpringApplication : Unable to close ApplicationContextorg.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'springApplicationAdminRegistrar' defined in class path resource [org/springframework/boot/autoconfigure/admin/SpringApplicationAdminJmxAutoConfiguration.class]: Unsatisfied dependency expressed through method 'springApplicationAdminRegistrar' parameter 1; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.core.env.Environment' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {} at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:798) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:539) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:226) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:207) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.context.event.AbstractApplicationEventMulticaster.retrieveApplicationListeners(AbstractApplicationEventMulticaster.java:245) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.context.event.AbstractApplicationEventMulticaster.getApplicationListeners(AbstractApplicationEventMulticaster.java:197) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:134) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:403) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.context.support.AbstractApplicationContext.publishEvent(AbstractApplicationContext.java:360) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.boot.availability.AvailabilityChangeEvent.publish(AvailabilityChangeEvent.java:81) ~[spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE] at org.springframework.boot.availability.AvailabilityChangeEvent.publish(AvailabilityChangeEvent.java:67) ~[spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.doClose(ServletWebServerApplicationContext.java:167) ~[spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE] at org.springframework.context.support.AbstractApplicationContext.close(AbstractApplicationContext.java:978) ~[spring-context-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.boot.SpringApplication.handleRunFailure(SpringApplication.java:814) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:325) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1237) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.3.0.RELEASE.jar:2.3.0.RELEASE] at com.example.DemoApplication.main(DemoApplication.java:10) [classes/:na]Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.core.env.Environment' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {} at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1716) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1272) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1226) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:885) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:789) ~[spring-beans-5.2.6.RELEASE.jar:5.2.6.RELEASE] ... 23 common frames omitted

　　

3.Setter注入多例（@AutoWired）