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1. 网关介绍

注意：spring cloud gateway 依赖，需要在spring boot和spring webflux提供的netty下运行，不能在Servlet容器中运行，也就是不能同时依赖spring-boot-starter-web

2. 使用

2.1 依赖

   
   	
    
     org.springframework.cloud
    	
    
     spring-cloud-starter-gateway
    
   

项目添加依赖后，直接启动主类GatewayApplication测试项目依赖包是否有冲突，正常启动如下图所示：

项目内没有任何方法，直接访问http://localhost:8080/xxx，出现白页，说明正常启动。

2.2 添加过滤规则和过滤器

在配置中配置要拦截的请求路径Path，然后编写过滤器进行拦截过滤。

2.3.3.1 yml配置

server:  port: 8080spring:  cloud:    gateway:      routes:        - id: provider          uri: http://localhost:8081/          ## 意思是对http://localhost:8080/provider/**的请求进行拦截，转发至http://localhost:8081/**          predicates:            - Path=/provider/**          ## 表示在将请求发送到下游之前从请求中剥离的路径个数，剥离1个，即http://localhost:8081/**          filters:            - StripPrefix=1        - id: consumer          uri: http://localhost:8083/          ## 意思是对http://localhost:8080/consumer/**的请求进行拦截，转发至http://localhost:8083/consumer/**          predicates:            - Path=/consumer/**

2.3.3.2 过滤器

自定义基于url的过滤器，实现GlobalFilter接口，重写filter方法。

package com.gs.gateway.filter;import org.springframework.cloud.gateway.filter.GatewayFilterChain;import org.springframework.cloud.gateway.filter.GlobalFilter;import org.springframework.http.server.reactive.ServerHttpRequest;import org.springframework.stereotype.Component;import org.springframework.web.server.ServerWebExchange;import reactor.core.publisher.Mono;@Componentpublic class UrlFilter implements GlobalFilter {
   	@Override	public Mono
   
     filter(ServerWebExchange exchange, GatewayFilterChain chain) {
   		ServerHttpRequest request = exchange.getRequest();		String url = request.getURI().getPath();		//TODO 拦截特定URL地址		System.out.println("url: " + url);		return chain.filter(exchange);	}}
   

2.3 测试

2.3.1 服务1provider

启动端口8081，内部有/index方法，输出一句话。

直接访问http://localhost:8081/index

2.3.2 服务2consumer

启动端口8083，内部有/consumer方法，实现对服务1provider的远程调用，并输出。

直接访问http://localhost:8083/consumer

2.3.3 网关

网关内部只实现了对url的拦截和转发，启动端口8080

• 访问http://localhost:8080/provider/index，成功拦截并转发到了服务1provider上。

  

• 访问http://localhost:8080/consumer，成功拦截并转发到了服务2consumer上。

  如果provider是个集群，再有一个8082端口的服务
  
  

• 访问http://localhost:8080/index，不满足配置的拦截规则，无法转发，而此时网关项目也没有/index的方法，故出现404，依旧证明网关拦截配置成功！

  

遇到的问题

集成spring-cloud-gateway 启动报以下错误：

**********************************************************Spring MVC found on classpath, which is incompatible with Spring Cloud Gateway at this time. Please remove spring-boot-starter-web dependency.**********************************************************2020-03-21 11:14:33.917  WARN 14524 --- [  restartedMain] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'gatewayConfigurationService' defined in class path resource [org/springframework/cloud/gateway/config/GatewayAutoConfiguration.class]: Unsatisfied dependency expressed through method 'gatewayConfigurationService' parameter 1; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.core.convert.ConversionService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {
   @org.springframework.beans.factory.annotation.Qualifier(value=webFluxConversionService)}2020-03-21 11:14:33.920  INFO 14524 --- [  restartedMain] o.apache.catalina.core.StandardService   : Stopping service [Tomcat]2020-03-21 11:14:33.931  INFO 14524 --- [  restartedMain] ConditionEvaluationReportLoggingListener : Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.2020-03-21 11:14:34.089 ERROR 14524 --- [  restartedMain] o.s.boot.SpringApplication               : Application run failedorg.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'gatewayConfigurationService' defined in class path resource [org/springframework/cloud/gateway/config/GatewayAutoConfiguration.class]: Unsatisfied dependency expressed through method 'gatewayConfigurationService' parameter 1; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.core.convert.ConversionService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {
   @org.springframework.beans.factory.annotation.Qualifier(value=webFluxConversionService)}	at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:787) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:528) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1338) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1177) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:557) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:517) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:323) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:321) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:202) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:879) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:878) ~[spring-context-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:550) ~[spring-context-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:141) ~[spring-boot-2.2.0.RELEASE.jar:2.2.0.RELEASE]	at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:747) [spring-boot-2.2.0.RELEASE.jar:2.2.0.RELEASE]	at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) [spring-boot-2.2.0.RELEASE.jar:2.2.0.RELEASE]	at org.springframework.boot.SpringApplication.run(SpringApplication.java:315) [spring-boot-2.2.0.RELEASE.jar:2.2.0.RELEASE]	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1226) [spring-boot-2.2.0.RELEASE.jar:2.2.0.RELEASE]	at org.springframework.boot.SpringApplication.run(SpringApplication.java:1215) [spring-boot-2.2.0.RELEASE.jar:2.2.0.RELEASE]	at com.dolphin.GateWayApplication.main(GateWayApplication.java:21) [classes/:na]	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.0_151]	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:1.8.0_151]	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.8.0_151]	at java.lang.reflect.Method.invoke(Method.java:498) ~[na:1.8.0_151]	at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49) [spring-boot-devtools-2.2.0.RELEASE.jar:2.2.0.RELEASE]Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'org.springframework.core.convert.ConversionService' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {
   @org.springframework.beans.factory.annotation.Qualifier(value=webFluxConversionService)}	at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoMatchingBeanFound(DefaultListableBeanFactory.java:1695) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1253) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1207) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:874) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:778) ~[spring-beans-5.2.0.RELEASE.jar:5.2.0.RELEASE]	... 24 common frames omittedDisconnected from the target VM, address: '127.0.0.1:50299', transport: 'socket'Process finished with exit code 0

因为spring cloud gateway 依赖，需要在spring boot和spring webflux提供的netty下运行，不能在Servlet容器中运行，也就是不能同时依赖spring-boot-starter-web。检查项目是否依赖web模块，如果有，移除再试一次。

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