目录一、背景二、使用feign理由三、解决方案四、demo代码实现4.1 接口编写4.2 接口发布4.3 调用4.4 结果(很明显,是异步调用)五、问题
一、背景
希望将http的调用由同步等待改为异步,仍使用feign的便捷。
二、使用feign理由
本质上其实feign就是将httpclient常用的操作进行简单封装,且屏蔽底层的httpclient,无感知具体的client实现,轻松完成具体client的替换
三、解决方案
feign在10.8版本后提供了Async接口,如下:
四、demo代码实现
4.1 接口编写
publicinterfaceOriginFeignClient {@RequestLine("POST /async/server/api")CompletableFuture<String> api(@Param("param") String param);}
4.2 接口发布
@Configurationpublic class OriginFeignClientConfig { @Bean public SpringEncoder springEncoder(ObjectFactory<HttpMessageConverters> messageConverters) { return new SpringEncoder(messageConverters); } @Bean public SpringDecoder springDecoder(ObjectFactory<HttpMessageConverters> messageConverters) { return new SpringDecoder(messageConverters); } @Bean public OriginFeignClient originFeignClient(SpringEncoder springEncoder, SpringDecoder springDecoder) { return AsyncFeign.asyncBuilder() .encoder(springEncoder) .decoder(springDecoder) .target(OriginFeignClient.class, "http://localhost.charlesproxy.com:8090"); }}
4.3 调用
@GetMapping("testApi") public String testAsyncClient() throws ExecutionException, InterruptedException { List<CompletableFuture<String>> results = new ArrayList<>(); for(int i = 0; i < 10; i++) { results.add(originFeignClient.api(i+"")); } Thread.sleep(3000); int index = 0; for (CompletableFuture<String> result : results) { String str = result.get(); log.info(String.format("%d, result:%s, ", index, str)); index++; } return "success"; }
4.4 结果(很明显,是异步调用)
2021-05-1114:31:29.989- INFO [TraceId: , SpanId : ]24745— [nio-8091-exec-5] c.m.a.c.controller.ClientController :0, result:receive: {“param”:”0″} at2021-05-1102:31:27.243,
2021-05-1114:31:29.993- INFO [TraceId: , SpanId : ]24745— [nio-8091-exec-5] c.m.a.c.controller.ClientController :1, result:receive: {“param”:”1″} at2021-05-1102:31:27.243,
2021-05-1114:31:29.995- INFO [TraceId: , SpanId : ]24745— [nio-8091-exec-5] c.m.a.c.controller.ClientController :2, result:receive: {“param”:”2″} at2021-05-1102:31:27.244,
2021-05-1114:31:29.995- INFO [TraceId: , SpanId : ]24745— [nio-8091-exec-5] c.m.a.c.controller.ClientController :3, result:receive: {“param”:”3″} at2021-05-1102:31:27.245,
2021-05-1114:31:29.995- INFO [TraceId: , SpanId : ]24745— [nio-8091-exec-5] c.m.a.c.controller.ClientController :4, result:receive: {“param”:”4″} at2021-05-1102:31:27.243,
2021-05-1114:31:29.996- INFO [TraceId: , SpanId : ]24745— [nio-8091-exec-5] c.m.a.c.controller.ClientController :5, result:receive: {“param”:”5″} at2021-05-1102:31:27.243,
2021-05-1114:31:29.996- INFO [TraceId: , SpanId : ]24745— [nio-8091-exec-5] c.m.a.c.controller.ClientController :6, result:receive: {“param”:”6″} at2021-05-1102:31:27.244,
2021-05-1114:31:29.997- INFO [TraceId: , SpanId : ]24745— [nio-8091-exec-5] c.m.a.c.controller.ClientController :7, result:receive: {“param”:”7″} at2021-05-1102:31:27.243,
2021-05-1114:31:29.997- INFO [TraceId: , SpanId : ]24745— [nio-8091-exec-5] c.m.a.c.controller.ClientController :8, result:receive: {“param”:”8″} at2021-05-1102:31:27.244,
2021-05-1114:31:29.998- INFO [TraceId: , SpanId : ]24745— [nio-8091-exec-5] c.m.a.c.controller.ClientController :9, result:receive: {“param”:”9″} at2021-05-1102:31:27.245,
五、问题
feign增加的async实现是10.8版本,我们找到Spring boot 2.2.13和相应cloud最新版Hoxton.SR11(当然不是最新,是该小版本下最新,因为目前项目中使用的就是该版本),排查思路就是以@EnableFeignClients为入口
1.EnableFeignClients内容如下
@Import(FeignClientsRegistrar.class)public @interface EnableFeignClients {}
引入了FeignClientsRegistrar
2.FeignClientsRegistrar功能如下:
(1)扫描@FeignClient,并将其下入到BeanDefinition中
(2)调用registerFeignClient,构造FeignClientFactoryBean(创建feign的工厂类,关键在此)
(3)进入FeignClientFactoryBean内部看下,构建feign的方法:getTarget():
从context中去找feign.Feign.Builder的实现(即@Bean),看下当前项目中有哪几种实现:
1.org.springframework.cloud.openfeign.FeignCircuitBreaker.Builder Spring Cloud定义的通用断路器
2.feign.hystrix.HystrixFeign.Builder 断路器的原生实现
先不管哪种builder,最终执行:loadBalance,方法内容如下:
protected <T> T loadBalance(Feign.Builder builder, FeignContext context,HardCodedTarget<T> target) {Client client = getOptional(context, Client.class);if (client != null) {builder.client(client);Targeter targeter = get(context, Targeter.class);return targeter.target(this, builder, context, target);} throw new IllegalStateException("No Feign Client for loadBalancing defined. Did you forget to include spring-cloud-starter-netflix-ribbon?");}
好了!!看到我们想要的了,Client的创建,不对,等等!!Client,我们先看下他的实现类是不是包含我们的AsyncClient,
一切幻想破灭
好了,所以目前的Spring cloud openfeign中仍未支持该特性,先这样用吧
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