我在my-core-framework中使用Java-17和Spring 2.6.7，并将其添加到另一个Spring项目中作为依赖项，但是在开始我的依赖项目时，即使我试图从子项目中排除重复的依赖项，也会出现以下错误。
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.6.7</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.my.core</groupId>
<artifactId>my-core</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>my-core</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>17</java.version>
<spring-cloud.version>2021.0.2</spring-cloud.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web-services</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-aop</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-sleuth</artifactId>
</dependency>
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
</dependencies>
<dependencyManagement>
<dependencies>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-dependencies</artifactId>
<version>${spring-cloud.version}</version>
<type>pom</type>
<scope>import</scope>
</dependency>
<dependency>
<groupId>org.springframework.cloud</groupId>
<artifactId>spring-cloud-starter-zipkin</artifactId>
<version>${spring-cloud.version}</version>
<scope>runtime</scope>
</dependency>
</dependencies>
</dependencyManagement>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
下面是子项目
4.0.0
<groupId>com.example</groupId>
<artifactId>microservice3</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>microservice3</name>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.6.3</version>
<relativePath /> <!-- lookup parent from repository -->
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
<maven.compiler.source>17</maven.compiler.source>
<maven.compiler.target>17</maven.compiler.target>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web-services</artifactId>
</dependency>
<dependency>
<groupId>com.my.core</groupId>
<artifactId>my-core</artifactId>
<version>0.0.1-SNAPSHOT</version>
<type>jar</type>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
</exclusion>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</exclusion>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web-services</artifactId>
</exclusion>
</exclusions>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
当开始子项目得到以下错误
org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'braveHttpServerHandler' defined in class path resource [org/springframework/cloud/sleuth/autoconfig/brave/instrument/web/BraveHttpBridgeConfiguration.class]: Unsatisfied dependency expressed through method 'braveHttpServerHandler' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'httpTracing' defined in class path resource [org/springframework/cloud/sleuth/autoconfig/brave/instrument/web/BraveHttpConfiguration.class]: Unsatisfied dependency expressed through method 'httpTracing' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'tracing' defined in class path resource [org/springframework/cloud/sleuth/autoconfig/brave/BraveAutoConfiguration.class]: Unsatisfied dependency expressed through method 'tracing' parameter 3; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'microservice3Controller': Unsatisfied dependency expressed through field 'restTemplate'; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'microservice3Controller': Requested bean is currently in creation: Is there an unresolvable circular reference?
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:800) ~[spring-beans-5.3.15.jar:5.3.15]
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:541) ~[spring-beans-5.3.15.jar:5.3.15]
..............
.
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1292) ~[spring-boot-2.6.3.jar:2.6.3]
at com.javainuse.Microservice3Application.main(Microservice3Application.java:22) ~[classes/:na]
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'httpTracing' defined in class path resource [org/springframework/cloud/sleuth/autoconfig/brave/instrument/web/BraveHttpConfiguration.class]: Unsatisfied dependency expressed through method 'httpTracing' parameter 0; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'tracing' defined in class path resource [org/springframework/cloud/sleuth/autoconfig/brave/BraveAutoConfiguration.class]: Unsatisfied dependency expressed through method 'tracing' parameter 3; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'microservice3Controller': Unsatisfied dependency expressed through field 'restTemplate'; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'microservice3Controller': Requested bean is currently in creation: Is there an unresolvable circular reference?
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:800) ~[spring-beans-5.3.15.jar:5.3.15]
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'tracing' defined in class path resource [org/springframework/cloud/sleuth/autoconfig/brave/BraveAutoConfiguration.class]: Unsatisfied dependency expressed through method 'tracing' parameter 3; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'microservice3Controller': Unsatisfied dependency expressed through field 'restTemplate'; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'microservice3Controller': Requested bean is currently in creation: Is there an unresolvable circular reference?
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:800) ~[spring-beans-5.3.15.jar:5.3.15]
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'microservice3Controller': Unsatisfied dependency expressed through field 'restTemplate'; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'microservice3Controller': Requested bean is currently in creation: Is there an unresolvable circular reference?
at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.resolveFieldValue(AutowiredAnnotationBeanPostProcessor.java:659) ~[spring-beans-5.3.15.jar:5.3.15]
Caused by: org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'microservice3Controller': Requested bean is currently in creation: Is there an unresolvable circular reference?
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.beforeSingletonCreation(DefaultSingletonBeanRegistry.java:355) ~[spring-beans-5.3.15.jar:5.3.15]
Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2022-06-02 00:47:47.270 ERROR [microservice3,,] 16932 --- [ main] o.s.boot.SpringApplication : Application run failed
org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:163) ~[spring-boot-2.6.3.jar:2.6.3]
............
Caused by: org.springframework.boot.web.server.WebServerException: Unable to start embedded Tomcat
at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatW
ebServer.java:142) ~[spring-boot-2.6.3.jar:2.6.3]
..............
Caused by: java.lang.IllegalStateException: StandardEngine[Tomcat].StandardHost[localhost].TomcatEmbeddedContext[] failed to start
at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.rethrowDeferredStartupExceptions(TomcatWebServer.java:187) ~[spring-boot-2.6.3.jar:2.6.3]
at org.springframework.boot.web.embedded.tomcat.TomcatWebServer.initialize(TomcatWebServer.java:126) ~[spring-boot-2.6.3.jar:2.6.3]
... 13 common frames omitted
Process finished with exit code 1
当自动配置Sleuth/Zipkin跟踪时，您的microservice3Controller和restTemplate之间存在一些循环依赖关系。
在Spring中有多种解决循环依赖的方法，例如@Lazybean自动装配，使用setter注入等。查看https://www.baeldung.com/circular-dependencies-in-spring获取更多详细信息。