记录关于springCloud 网关从zuul升级到gateway所遇到的问题

网关服务最开始引入的主要依赖版本如下：

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
</parent>
 
<properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
        <spring-cloud.version>Finchley.SR1</spring-cloud.version>
</properties>

但是当服务启动时，一直抛出如下异常：

Parameter 0 of method websocketRoutingFilter in org.springframework.cloud.gateway.config.GatewayAutoConfiguration 
	required a bean of type 'org.springframework.web.reactive.socket.client.WebSocketClient' 
	that could not be found. The following candidates were found but could not be injected: 
	- Bean method 'reactorNettyWebSocketClient' in 'GatewayAutoConfiguration.NettyConfiguration' not loaded because 
	- @ConditionalOnClass did not find required class 'reactor.ipc.netty.http.client.HttpClient'

花费大量时间排查原因，最终找到问题是因为gateway服务使用springcloud的Finchley版本与springboot 2.1不兼容。建议是要么降级到引导2.0.6，要么springcloud使用Greenwich.M3，最终采用Greenwich.M3，

启动正常！！！

来源：https://github.com/spring-cloud/spring-cloud-gateway/issues/319