本篇内容主要讲解“spring cloud的FeignLoadBalancer怎么用”，感兴趣的朋友不妨来看看。本文介绍的方法操作简单快捷，实用性强。下面就让小编来带大家学习“spring cloud的FeignLoadBalancer怎么用”吧!

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序

本文主要研究一下spring cloud的FeignLoadBalancer

FeignLoadBalancer

spring-cloud-openfeign-core-2.2.0.M1-sources.jar!/org/springframework/cloud/openfeign/ribbon/FeignLoadBalancer.java

public class FeignLoadBalancer extends
		AbstractLoadBalancerAwareClient {

	private final RibbonProperties ribbon;

	protected int connectTimeout;

	protected int readTimeout;

	protected IClientConfig clientConfig;

	protected ServerIntrospector serverIntrospector;

	public FeignLoadBalancer(ILoadBalancer lb, IClientConfig clientConfig,
			ServerIntrospector serverIntrospector) {
		super(lb, clientConfig);
		this.setRetryHandler(RetryHandler.DEFAULT);
		this.clientConfig = clientConfig;
		this.ribbon = RibbonProperties.from(clientConfig);
		RibbonProperties ribbon = this.ribbon;
		this.connectTimeout = ribbon.getConnectTimeout();
		this.readTimeout = ribbon.getReadTimeout();
		this.serverIntrospector = serverIntrospector;
	}

	@Override
	public RibbonResponse execute(RibbonRequest request, IClientConfig configOverride)
			throws IOException {
		Request.Options options;
		if (configOverride != null) {
			RibbonProperties override = RibbonProperties.from(configOverride);
			options = new Request.Options(override.connectTimeout(this.connectTimeout),
					override.readTimeout(this.readTimeout));
		}
		else {
			options = new Request.Options(this.connectTimeout, this.readTimeout);
		}
		Response response = request.client().execute(request.toRequest(), options);
		return new RibbonResponse(request.getUri(), response);
	}

	@Override
	public RequestSpecificRetryHandler getRequestSpecificRetryHandler(
			RibbonRequest request, IClientConfig requestConfig) {
		if (this.ribbon.isOkToRetryOnAllOperations()) {
			return new RequestSpecificRetryHandler(true, true, this.getRetryHandler(),
					requestConfig);
		}
		if (!request.toRequest().httpMethod().name().equals("GET")) {
			return new RequestSpecificRetryHandler(true, false, this.getRetryHandler(),
					requestConfig);
		}
		else {
			return new RequestSpecificRetryHandler(true, true, this.getRetryHandler(),
					requestConfig);
		}
	}

	@Override
	public URI reconstructURIWithServer(Server server, URI original) {
		URI uri = updateToSecureConnectionIfNeeded(original, this.clientConfig,
				this.serverIntrospector, server);
		return super.reconstructURIWithServer(server, uri);
	}

	//......
}

• FeignLoadBalancer继承了AbstractLoadBalancerAwareClient，它的构造器接收ILoadBalancer、IClientConfig、ServerIntrospector，设置的retryHandler为RetryHandler.DEFAULT

• 其execute方法首先构造Request.Options，然后通过request.client().execute来获取Response，最后返回RibbonResponse

• FeignLoadBalancer还覆盖了getRequestSpecificRetryHandler方法，针对ribbon.isOkToRetryOnAllOperations()来构建不同的RequestSpecificRetryHandler；还覆盖了reconstructURIWithServer方法，它使用RibbonUtils的updateToSecureConnectionIfNeeded来构建URI

RibbonRequest

spring-cloud-openfeign-core-2.2.0.M1-sources.jar!/org/springframework/cloud/openfeign/ribbon/FeignLoadBalancer.java

	protected static class RibbonRequest extends ClientRequest implements Cloneable {

		private final Request request;

		private final Client client;

		protected RibbonRequest(Client client, Request request, URI uri) {
			this.client = client;
			setUri(uri);
			this.request = toRequest(request);
		}

		private Request toRequest(Request request) {
			Map> headers = new LinkedHashMap<>(
					request.headers());
			return Request.create(request.httpMethod(), getUri().toASCIIString(), headers,
					request.requestBody());
		}

		Request toRequest() {
			return toRequest(this.request);
		}

		Client client() {
			return this.client;
		}

		HttpRequest toHttpRequest() {
			return new HttpRequest() {
				@Override
				public HttpMethod getMethod() {
					return HttpMethod
							.resolve(RibbonRequest.this.toRequest().httpMethod().name());
				}

				@Override
				public String getMethodValue() {
					return getMethod().name();
				}

				@Override
				public URI getURI() {
					return RibbonRequest.this.getUri();
				}

				@Override
				public HttpHeaders getHeaders() {
					Map> headers = new HashMap<>();
					Map> feignHeaders = RibbonRequest.this
							.toRequest().headers();
					for (String key : feignHeaders.keySet()) {
						headers.put(key, new ArrayList(feignHeaders.get(key)));
					}
					HttpHeaders httpHeaders = new HttpHeaders();
					httpHeaders.putAll(headers);
					return httpHeaders;

				}
			};
		}

		public Request getRequest() {
			return this.request;
		}

		public Client getClient() {
			return this.client;
		}

		@Override
		public Object clone() {
			return new RibbonRequest(this.client, this.request, getUri());
		}

	}

• RibbonRequest继承了ClientRequest实现了Cloneable接口，它提供了toHttpRequest方法来将feign的Request转换为spring的HttpRequest

RibbonResponse

spring-cloud-openfeign-core-2.2.0.M1-sources.jar!/org/springframework/cloud/openfeign/ribbon/FeignLoadBalancer.java

	protected static class RibbonResponse implements IResponse {

		private final URI uri;

		private final Response response;

		protected RibbonResponse(URI uri, Response response) {
			this.uri = uri;
			this.response = response;
		}

		@Override
		public Object getPayload() throws ClientException {
			return this.response.body();
		}

		@Override
		public boolean hasPayload() {
			return this.response.body() != null;
		}

		@Override
		public boolean isSuccess() {
			return this.response.status() == 200;
		}

		@Override
		public URI getRequestedURI() {
			return this.uri;
		}

		@Override
		public Map> getHeaders() {
			return this.response.headers();
		}

		Response toResponse() {
			return this.response;
		}

		@Override
		public void close() throws IOException {
			if (this.response != null && this.response.body() != null) {
				this.response.body().close();
			}
		}

	}

• RibbonResponse实现了IResponse接口，将feign的Response适配为netflix的IResponse

小结

• FeignLoadBalancer继承了AbstractLoadBalancerAwareClient，它的构造器接收ILoadBalancer、IClientConfig、ServerIntrospector，设置的retryHandler为RetryHandler.DEFAULT

• 其execute方法首先构造Request.Options，然后通过request.client().execute来获取Response，最后返回RibbonResponse

• FeignLoadBalancer还覆盖了getRequestSpecificRetryHandler方法，针对ribbon.isOkToRetryOnAllOperations()来构建不同的RequestSpecificRetryHandler；还覆盖了reconstructURIWithServer方法，它使用RibbonUtils的updateToSecureConnectionIfNeeded来构建URI

到此，相信大家对“spring cloud的FeignLoadBalancer怎么用”有了更深的了解，不妨来实际操作一番吧！这里是创新互联网站，更多相关内容可以进入相关频道进行查询，关注我们，继续学习！

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