春天云网关；在类路径上发现 Spring MVC，与 Spring Cloud Gateway 不兼容问题

Posted 2023-02-26

【中文标题】春天云网关；在类路径上发现 Spring MVC，与 Spring Cloud Gateway 不兼容问题

【英文标题】：Spring Cloud Gateway; Spring MVC found on classpath, which is incompatible with Spring Cloud Gateway Issue

【发布时间】：2021-10-05 19:32:31

【问题描述】：

我在运行 API-GATEWAY 时遇到以下错误，我尝试了很多方法，但我无法解决这个问题。

说明：

在类路径中发现 Spring MVC，与 Spring Cloud Gateway 不兼容。

行动：

请设置 spring.main.web-application-type=reactive 或移除 spring-boot-starter-web 依赖。

主类

package com.sample.apigateway;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;

@SpringBootApplication
@EnableEurekaClient
public class ApiGatewayApplication 

    public static void main(String[] args) 
        SpringApplication.run(ApiGatewayApplication.class, args);
    

application.yml

spring:
  application:
    name: GATEWAY-SERVICE

  cloud:
    gateway:
      routes:
        - id: USER-SERVICE
          uri: lb://USER-SERVICE
          predicates:
            - Path=/users/**
        - id: DEPARTMENT-SERVICE
          uri: lb://DEPARTMENT-SERVICE
          predicates:
            - Path=/departments/**

eureka:
  client:
    register-with-eureka: true
    fetch-registry: true
    service-url:
      defaultZone: http://localhost:8761/eureka/

  instance:
    hostname: localhost

server:
  port: 9191

pom.xml

<?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>2.5.3</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.sample.apigateway</groupId>
    <artifactId>apigateway</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>apigateway</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>11</java.version>
        <spring-cloud.version>2020.0.3</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-webflux</artifactId>
        </dependency>
        <dependency>
            <groupId>io.springfox</groupId>
            <artifactId>springfox-boot-starter</artifactId>
            <version>3.0.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-gateway</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
        </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>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

</project>

完整的错误信息

2021-07-30 23:12:02.420  WARN 19032 --- [           main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'org.springframework.cloud.gateway.config.GatewayClassPathWarningAutoConfiguration$SpringMvcFoundOnClasspathConfiguration': Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [org.springframework.cloud.gateway.config.GatewayClassPathWarningAutoConfiguration$SpringMvcFoundOnClasspathConfiguration]: Constructor threw exception; nested exception is org.springframework.cloud.gateway.support.MvcFoundOnClasspathException
2021-07-30 23:12:02.423  INFO 19032 --- [           main] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]
2021-07-30 23:12:02.441  INFO 19032 --- [           main] ConditionEvaluationReportLoggingListener : 

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
2021-07-30 23:12:02.454 ERROR 19032 --- [           main] o.s.b.d.LoggingFailureAnalysisReporter   : 

***************************
APPLICATION FAILED TO START
***************************

Description:

Spring MVC found on classpath, which is incompatible with Spring Cloud Gateway.

Action:

Please set spring.main.web-application-type=reactive or remove spring-boot-starter-web dependency.


Process finished with exit code 1

【问题讨论】：

你能提供确切的错误信息或堆栈跟踪吗？

更新了问题兄弟。

Spring Cloud Gateway 是 Spring Cloud 团队在 Spring 响应式生态系统之上实现的 API Gateway。因此添加建议的属性 [spring.main.web-application-type=reactive]。

#Arun 我做了所有建议的事情，但错误没有解决..

【参考方案1】：

我遇到了类似的问题。 正如错误部分中所建议的那样，对 application.properties 文件进行以下更改对我来说效果很好。

spring.main.web-application-type=reactive

【讨论】：

这是正确的做法吗？这意味着我必须使我的应用程序适应 spring webflux

【参考方案2】：

请注意Spring Cloud Gateway 与 Spring MVC (spring-boot-starter-web) 不兼容。这在section "How to include Spring Cloud Gateway in the official reference documentation" 中有概述：

Spring Cloud Gateway 基于 Spring Boot 2.x、Spring WebFlux 和 Project Reactor 构建。因此，当您使用 Spring Cloud Gateway 时，许多您熟悉的同步库（例如 Spring Data 和 Spring Security）和模式可能并不适用。

另外说明：

Spring Cloud Gateway 需要 Spring Boot 和 Spring Webflux 提供的 Netty 运行时。它不适用于传统的 Servlet 容器或构建为 WAR。

正如错误消息已经建议的那样，您需要删除对spring-boot-starter-web 的依赖。您可以使用以下命令列出所有直接和传递依赖项：

mvn dependency:tree

这将表明spring-cloud-starter-netflix-eureka-server 依赖于spring-boot-starter-web。从 pom.xml 中删除以下行后，您的应用程序应该会启动：

<dependency>
    <groupId>org.springframework.cloud</groupId>
    <artifactId>spring-cloud-starter-netflix-eureka-server</artifactId>
</dependency>

【讨论】：

Spring Cloud Gateway requires the Netty runtime provided by Spring Boot and Spring Webflux. It does not work in a traditional Servlet Container or when built as a WAR.。这意味着我们无法为网关构建 WAR 并部署在 tomcat 中？

不，这个不支持，另见docs.spring.io/spring-boot/docs/current/reference/html/…：“由于Spring WebFlux不严格依赖Servlet API，应用默认部署在嵌入式Reactor Netty服务器上，War部署是不支持 WebFlux 应用程序。”

好，那我们如何在生产环境部署spring cloud gateway（Spring boot webflux）呢？

创建 JAR 存档而不是 WAR 存档并在目标环境中运行：java -jar archive.jar

但是在生产环境中推荐吗？我的意思是可扩展且稳定吗？我也无法弄清楚我们如何为网关设置上下文路径。尝试设置spring.webflux.base-path，但没有成功。