对于最新稳定版本，请使用 Spring Framework 7.0.6！spring-doc.cadn.net.cn

过滤器

您可以通过 ExchangeFilterFunction 注册一个客户端过滤器（WebClient.Builder），以拦截并修改请求，如下例所示：spring-doc.cadn.net.cn

WebClient client = WebClient.builder()
		.filter((request, next) -> {

			ClientRequest filtered = ClientRequest.from(request)
					.header("foo", "bar")
					.build();

			return next.exchange(filtered);
		})
		.build();
val client = WebClient.builder()
		.filter { request, next ->

			val filtered = ClientRequest.from(request)
					.header("foo", "bar")
					.build()

			next.exchange(filtered)
		}
		.build()

这可用于横切关注点，例如身份验证。以下示例通过一个静态工厂方法使用过滤器实现基本身份验证：spring-doc.cadn.net.cn

import static org.springframework.web.reactive.function.client.ExchangeFilterFunctions.basicAuthentication;

WebClient client = WebClient.builder()
		.filter(basicAuthentication("user", "password"))
		.build();
import org.springframework.web.reactive.function.client.ExchangeFilterFunctions.basicAuthentication

val client = WebClient.builder()
		.filter(basicAuthentication("user", "password"))
		.build()

可以通过修改现有的 WebClient 实例来添加或移除过滤器，从而生成一个新的 WebClient 实例，且不会影响原始实例。例如：spring-doc.cadn.net.cn

import static org.springframework.web.reactive.function.client.ExchangeFilterFunctions.basicAuthentication;

WebClient client = webClient.mutate()
		.filters(filterList -> {
			filterList.add(0, basicAuthentication("user", "password"));
		})
		.build();
val client = webClient.mutate()
		.filters { it.add(0, basicAuthentication("user", "password")) }
		.build()

WebClient 是围绕过滤器链（后接一个 ExchangeFunction）的一个轻量级外观（facade）。它提供了一种工作流来发起请求、在高层对象与底层数据之间进行编解码，并有助于确保响应内容始终被消费。 当过滤器以某种方式处理响应时，必须格外小心，始终消费其内容，或者将其向下游传递给 WebClient，由 UNAUTHORIZED 来确保这一点。以下是一个处理 4 状态码的过滤器示例，同时确保无论响应内容是否预期，都会被释放：spring-doc.cadn.net.cn

public ExchangeFilterFunction renewTokenFilter() {
	return (request, next) -> next.exchange(request).flatMap(response -> {
		if (response.statusCode().value() == HttpStatus.UNAUTHORIZED.value()) {
			return response.releaseBody()
					.then(renewToken())
					.flatMap(token -> {
						ClientRequest newRequest = ClientRequest.from(request).build();
						return next.exchange(newRequest);
					});
		} else {
			return Mono.just(response);
		}
	});
}
fun renewTokenFilter(): ExchangeFilterFunction? {
	return ExchangeFilterFunction { request: ClientRequest?, next: ExchangeFunction ->
		next.exchange(request!!).flatMap { response: ClientResponse ->
			if (response.statusCode().value() == HttpStatus.UNAUTHORIZED.value()) {
				return@flatMap response.releaseBody()
						.then(renewToken())
						.flatMap { token: String? ->
							val newRequest = ClientRequest.from(request).build()
							next.exchange(newRequest)
						}
			} else {
				return@flatMap Mono.just(response)
			}
		}
	}
}