关于Springboot+gateway整合依赖并处理依赖冲突问题

spring boot版本和spring cloud版本

pom依赖

<parent>
       <groupId>org.springframework.boot</groupId>
       <artifactId>spring-boot-starter-parent</artifactId>
       <version>2.3.12.RELEASE</version>
       <relativePath/>
   </parent>

<dependencies>
       <!-- spring-boot-starter -->
       <dependency>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter</artifactId>
       </dependency>

<!-- gateway与spring-boot-starter-web冲突(spring-boot-starter-webflux) -->
       <!--<dependency>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter-web</artifactId>
       </dependency>-->

<!-- springCloud gateway -->
       <dependency>
           <groupId>org.springframework.cloud</groupId>
           <artifactId>spring-cloud-starter-gateway</artifactId>
           <!--<exclusions>
               <exclusion>
                   <groupId>org.springframework.boot</groupId>
                   <artifactId>spring-boot-starter-webflux</artifactId>
               </exclusion>
           </exclusions>-->
       </dependency>

<!-- httpClient依赖,缺少此依赖api网关转发请求时可能发生503错误 -->
       <dependency>
           <groupId>org.apache.httpcomponents</groupId>
           <artifactId>httpclient</artifactId>
           <version>4.5.5</version>
       </dependency>
   </dependencies>

<dependencyManagement>
       <dependencies>
           <dependency>
               <groupId>org.springframework.cloud</groupId>
               <artifactId>spring-cloud-dependencies</artifactId>
               <version>Hoxton.SR1</version>
               <type>pom</type>
               <scope>import</scope>
           </dependency>
       </dependencies>
   </dependencyManagement>

配置文件（application.yml）

server:
 port: 8700
spring:
 application:
   name: sca-gateway
 cloud:
   gateway:
     routes: #配置网关路由规则
       - id: route01  #路由id,自己指定一个唯一值即可
         uri: http://localhost:8081/ #网关帮我们转发的url
         predicates: ###断言(谓此):匹配请求规则
           - Path=/nacos/provider/echo/**  #请求路径定义,此路径对应uri中的资源
         filters: ##网关过滤器,用于对谓词中的内容进行判断分析以及处理
           - StripPrefix=1 #转发之前去掉path中第一层路径，例如nacos

依赖冲突问题

**********************************************************
Spring MVC found on classpath, which is incompatible with Spring Cloud Gateway at this time. Please remove spring-boot-starter-web dependency.
**********************************************************
2020-07-21 10:12:27.253  WARN 8576 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'gatewayControllerEndpoint' defined in class path resource [org/springframework/cloud/gateway/config/GatewayAutoConfiguration$GatewayActuatorConfiguration.class]: Unsatisfied dependency expressed through method 'gatewayControllerEndpoint' parameter 1; nested exception is org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'modifyRequestBodyGatewayFilterFactory' defined in class path resource [org/springframework/cloud/gateway/config/GatewayAutoConfiguration.class]: Unsatisfied dependency expressed through method 'modifyRequestBodyGatewayFilterFactory' parameter 0; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.http.codec.ServerCodecConfigurer' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {}
2020-07-21 10:12:27.253  INFO 8576 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2020-07-21 10:12:27.273  INFO 8576 --- [           main] ConditionEvaluationReportLoggingListener : 
Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2020-07-21 10:12:27.388 ERROR 8576 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 
***************************
APPLICATION FAILED TO START
***************************
Description:
Parameter 0 of method modifyRequestBodyGatewayFilterFactory in org.springframework.cloud.gateway.config.GatewayAutoConfiguration required a bean of type 'org.springframework.http.codec.ServerCodecConfigurer' that could not be found.
Action:
Consider defining a bean of type 'org.springframework.http.codec.ServerCodecConfigurer' in your configuration.
2020-07-21 10:12:27.398  WARN 8576 --- [           main] o.s.boot.SpringApplication               : Unable to close ApplicationContext
org.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 online.hupeng.cloud.gateway.GateWayApplication.main(GateWayApplication.java:12) [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

注：spring-cloud-starter-gateway和spring-boot-starter-web依赖发生冲突，因为gateway依赖包内置spring-boot-starter-webflux依赖，与web包内的spring-boot-starter-webflux依赖起了冲突。

解决方法

将spring-boot-starter-webspring-依赖包剔除，或剔除boot-starter-webflux依赖包。

1. 剔除web包
<!-- gateway与spring-boot-starter-web冲突(spring-boot-starter-webflux) -->
<!--<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>-->
1. 剔除webflux包
<!-- gateway与spring-boot-starter-web冲突(spring-boot-starter-webflux) -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>     <exclusions>          <exclusion>               <groupId>org.springframework.boot</groupId>               <artifactId>spring-boot-starter-webflux</artifactId>          </exclusion>     </exclusions></dependency>

来源：https://www.cnblogs.com/nhdlb/p/15771808.html