spring cloud版本升级记录(2) SCG升级到Hoxton.SR12遇到openfeign调用问题记录

Spring cloud gateway 升级到Hoxton.SR12之后，在Token验证的filter里，通过openfeign调用User Auth服务时，碰到如下错误：

 

java.lang.IllegalStateException: block()/blockFirst()/blockLast() are blocking, which is not supported in thread reactor-http-nio-3
	at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:83)
	Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException: 
Error has been observed at the following site(s):
	|_ checkpoint ⇢ net.hzwei.spc.gateway.filter.CrossDomainFilter [DefaultWebFilterChain]
	|_ checkpoint ⇢ org.springframework.cloud.gateway.filter.WeightCalculatorWebFilter [DefaultWebFilterChain]
	|_ checkpoint ⇢ org.springframework.cloud.sleuth.instrument.web.TraceWebFilter [DefaultWebFilterChain]
	|_ checkpoint ⇢ org.springframework.boot.actuate.metrics.web.reactive.server.MetricsWebFilter [DefaultWebFilterChain]
	|_ checkpoint ⇢ HTTP GET "/api/company/list" [ExceptionHandlingWebHandler]
Stack trace:
		at reactor.core.publisher.BlockingSingleSubscriber.blockingGet(BlockingSingleSubscriber.java:83)
		at reactor.core.publisher.Mono.block(Mono.java:1685)
		at org.springframework.cloud.loadbalancer.blocking.client.BlockingLoadBalancerClient.choose(BlockingLoadBalancerClient.java:86)
		at org.springframework.cloud.openfeign.loadbalancer.FeignBlockingLoadBalancerClient.execute(FeignBlockingLoadBalancerClient.java:62)
		at org.springframework.cloud.sleuth.instrument.web.client.feign.TraceFeignBlockingLoadBalancerClient.execute(TraceFeignBlockingLoadBalancerClient.java:75)
		at feign.SynchronousMethodHandler.executeAndDecode(SynchronousMethodHandler.java:119)
		at feign.SynchronousMethodHandler.invoke(SynchronousMethodHandler.java:89)
		at feign.ReflectiveFeign$FeignInvocationHandler.invoke(ReflectiveFeign.java:100)
		at com.sun.proxy.$Proxy155.validToken(Unknown Source)
		at net.hzwei.spc.gateway.filter.TokenCheckFilter.checkToken(TokenCheckFilter.java:146)
		at net.hzwei.spc.gateway.filter.TokenCheckFilter.filter(TokenCheckFilter.java:95)

  这是因为FeignResp<LoginUserResp> resp = authClient.validToken(vToken) 调用是同步调用，而SCG使用了Reactor开发的响应式组件，运用了大量的异步实现，所以需要将authClient.validToken(vToken)改为异步调用：

 ThreadPoolExecutor exe = .....

Future<FeignResp<LoginUserResp>> future = exe.submit(() -> authClient.validToken(vToken));

FeignResp<LoginUserResp> resp = future.get(8, TimeUnit.SECONDS);

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解决了同步/异步调用问题，又遇到如下错误：

 

java.util.concurrent.ExecutionException: feign.codec.DecodeException: No qualifying bean of type 'org.springframework.boot.autoconfigure.http.HttpMessageConverters' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
	at java.util.concurrent.FutureTask.report(FutureTask.java:122)
	at java.util.concurrent.FutureTask.get(FutureTask.java:206)

 这是因为Spring Cloud Gateway是基于WebFlux的，是ReactiveWeb，所不会自动注入以HttpMessageConverters实例，需要我们自己注入：

    @Bean
    public feign.codec.Decoder decoder(){
        return new ResponseEntityDecoder(new SpringDecoder(feignHttpMessageConverter()));
    }
    
    private ObjectFactory<HttpMessageConverters> feignHttpMessageConverter(){
        HttpMessageConverters httpMessageConverters = new HttpMessageConverters(new MappingJackson2HttpMessageConverter());
        return () -> httpMessageConverters;
    }