spring-cloud-gateway啟動踩坑

本人使用的版本是2.1.2,以下只記錄幾個小問題，但確實實實在在的把個人惡心的要死要活的找不到辦法，幾經(jīng)掙扎，最終解決。

更可恨的是開發(fā)的過程中，沒有出現(xiàn)異常，后來由于項目組其它人加了依賴，不知不覺對項目的兼容造成了英雄，真的是被撞的頭破血流，才找到原因

1、webflux與mvc不兼容

如類路徑中引用了webmvc會導(dǎo)致項目啟動不起來

異常1

org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.context.ApplicationContextException: Unable to start ServletWebServerApplicationContext due to missing ServletWebServerFactory bean.

異常2

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)}

解決辦法，找到依賴webmvc的jar包，將webmvc排除即可，如

<dependency>
   <groupId>${project.groupId}</groupId>
   <artifactId>core</artifactId>
   <version>${project.version}</version>
   <exclusions>
        <!--
            1. webflux與webmvc不兼容，否則會項目啟動不起來
        -->
        <exclusion>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
        </exclusion>
</dependency>

2、webflux使用netty作為容器

不能使用tomcat，表現(xiàn)形式為網(wǎng)關(guān)工作轉(zhuǎn)發(fā)正常，目標(biāo)服務(wù)返回數(shù)據(jù)也正常，但是網(wǎng)關(guān)會無法解析返回的數(shù)據(jù)并最終由網(wǎng)關(guān)將數(shù)據(jù)返回給客戶端

java.lang.ClassCastException: org.springframework.core.io.buffer.DefaultDataBufferFactory cannot be cast to org.springframework.core.io.buffer.NettyDataBufferFactory

解決辦法

https://github.com/spring-cloud/spring-cloud-gateway/issues/145

找到將tomcat依賴進(jìn)來的jar包，然后排除即可。需要注意的是，要看清楚自己項目依賴的tomcat具體的maven坐標(biāo)。

然后排除即可

<dependency>
  <groupId>${project.groupId}</groupId>
  <artifactId>core</artifactId>
  <version>${project.version}</version>
  <exclusions>
      <!--
          1. webflux與webmvc不兼容，否則會項目啟動不起來
          2. webflux使用Netty作為容器，如果使用tomcat，接口轉(zhuǎn)發(fā)正常，但是會導(dǎo)致服務(wù)間的數(shù)據(jù)無法解析
              java.lang.ClassCastException: org.springframework.core.io.buffer.DefaultDataBufferFactory
              cannot be cast to org.springframework.core.io.buffer.NettyDataBufferFactory -->
      <exclusion>
          <groupId>org.springframework</groupId>
          <artifactId>spring-webmvc</artifactId>
      </exclusion>
      <exclusion>
          <groupId>org.springframework.bootk</groupId>
          <artifactId>spring-boot-starter-tomcat</artifactId>
      </exclusion>
      <exclusion>
          <groupId>org.apache.tomcat.embed</groupId>
          <artifactId>tomcat-embed-core</artifactId>
      </exclusion>
      <exclusion>
          <groupId>org.apache.tomcat.embed</groupId>
          <artifactId>tomcat-embed-el</artifactId>
      </exclusion>
      <exclusion>
          <groupId>org.apache.tomcat.embed</groupId>
          <artifactId>tomcat-embed-websocket</artifactId>
      </exclusion>
  </exclusions>
</dependency>

3、后來實驗了下

關(guān)于1webflux和mvc不兼容項目啟動不起來的異常，如果項目中存在了tomcat的用來，則拋出的異常是

org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.context.ApplicationContextException: Unable to start ServletWebServerApplicationContext due to missing ServletWebServerFactory bean.

而如果沒有依賴tomcat則拋出的異常是

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)}

很坑得spring cloud gateway 異常

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:1655) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1214) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1168) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:857) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:760) ~[spring-beans-5.1.7.RELEASE.jar:5.1.7.RELEASE]
... 101 common frames omitted

這個異常是因為spring cloud gateway 是webflux 項目，引了含有web-starter得項目就會出現(xiàn)沖突。因為Hystrix-dashboard中含有web-starter，所以出現(xiàn)沖突。

以上為個人經(jīng)驗，希望能給大家一個參考，也希望大家多多支持腳本之家。

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