4.3章，解决feign第一次调用失败的问题

[homeant]

我并没有看过书籍，我在这里说出我的疑问：

在FeignAutoConfiguration的源代码中，明确指出

	// the following configuration is for alternate feign clients if
	// ribbon is not on the class path.
	// see corresponding configurations in FeignRibbonClientAutoConfiguration
	// for load balanced ribbon clients.
	@Configuration
	@ConditionalOnClass(ApacheHttpClient.class)
	@ConditionalOnMissingClass("com.netflix.loadbalancer.ILoadBalancer")
	@ConditionalOnProperty(value = "feign.httpclient.enabled", matchIfMissing = true)
	protected static class HttpClientFeignConfiguration {

		@Autowired(required = false)
		private HttpClient httpClient;

		@Bean
		@ConditionalOnMissingBean(Client.class)
		public Client feignClient() {
			if (this.httpClient != null) {
				return new ApacheHttpClient(this.httpClient);
			}
			return new ApacheHttpClient();
		}
	}	

    @Configuration
	@ConditionalOnClass(OkHttpClient.class)
	@ConditionalOnMissingClass("com.netflix.loadbalancer.ILoadBalancer")
	@ConditionalOnProperty(value = "feign.okhttp.enabled", matchIfMissing = true)
	protected static class OkHttpFeignConfiguration {

		@Autowired(required = false)
		private okhttp3.OkHttpClient okHttpClient;

		@Bean
		@ConditionalOnMissingBean(Client.class)
		public Client feignClient() {
			if (this.okHttpClient != null) {
				return new OkHttpClient(this.okHttpClient);
			}
			return new OkHttpClient();
		}
	}

1. 首先，cloud代码中先是使用的是httpClient,但是在下面的代码有又有只要存在okhttp包，启用okhttp,仔细看咱们的源码，可以看出，咱们引用了okhttp的包，所以是生效的，只要feign.okhttp.enabled=true那么，okhttp就是生效的，咱们的配置文件就没有作用了。
2. 我们考虑首次为何会失败的问题，查阅代码能找到，feign默认的超时参数是这样的

private final int connectTimeoutMillis;
private final int readTimeoutMillis;

public Options(int connectTimeoutMillis, int readTimeoutMillis) {
  this.connectTimeoutMillis = connectTimeoutMillis;
  this.readTimeoutMillis = readTimeoutMillis;
}

public Options() {
  this(10 * 1000, 60 * 1000);
}

啥意思呢

1. connectTimeoutMillis连接超时的时间为：10*1000 就是10秒
2. readTimeoutMillis 读取超时时间为：60*1000 也就是一分钟

那么@SoftwareKing 同学提交的代码是怎么样的呢：

 @Bean
 public okhttp3.OkHttpClient okHttpClient(){
     return new okhttp3.OkHttpClient.Builder()
              //设置连接超时
             .connectTimeout(60, TimeUnit.SECONDS)
             //设置读超时
             .readTimeout(60, TimeUnit.SECONDS)
             //设置写超时
             .writeTimeout(60,TimeUnit.SECONDS)
             //是否自动重连
             .retryOnConnectionFailure(true)
             .connectionPool(new ConnectionPool())
             //构建OkHttpClient对象
             .build();
 }

设置了，一分钟的超时时间，所以就解决了首次超时的问题。

为何10秒钟连接不到服务或者响应不会来呢，想必书籍里面应该已经提及到了，我就不就阐述了