过滤器 (Filters) _ Spring Framework6.1.13中文文档(官方文档中文翻译)|Spring 教程 —

您可以通过注册客户端过滤器（）以拦截和修改请求，如下例所示：ExchangeFilterFunctionWebClient.Builderspring-doc.cn

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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。以下示例使用通过静态工厂方法进行基本身份验证的过滤器：spring-doc.cn

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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()

可以通过更改现有实例来添加或删除过滤器，从而在不影响原始实例的新实例中。例如：WebClientWebClientspring-doc.cn

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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是围绕过滤器链的薄立面，后跟 .它提供了一个工作流来发出请求、编码到更高级别或从更高级别编码 level 对象，它有助于确保始终使用响应内容。当 filter 以某种方式处理响应时，必须格外小心地始终使用其内容或以其他方式将其传播到下游，这将确保一样。下面是一个处理状态代码的筛选器，但确保任何响应内容（无论是否预期）都会被释放：ExchangeFunctionWebClientUNAUTHORIZEDspring-doc.cn

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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)
			}
		}
	}
}

下面的示例演示了如何使用接口创建一个自定义 Filter 类，可帮助使用缓冲计算 AND 请求的标头。ExchangeFilterFunctionContent-LengthPUTPOSTmultipart/form-dataspring-doc.cn

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public class MultipartExchangeFilterFunction implements ExchangeFilterFunction {

    @Override
    public Mono<ClientResponse> filter(ClientRequest request, ExchangeFunction next) {
        if (MediaType.MULTIPART_FORM_DATA.includes(request.headers().getContentType())
                && (request.method() == HttpMethod.PUT || request.method() == HttpMethod.POST)) {
            return next.exchange(ClientRequest.from(request).body((outputMessage, context) ->
                request.body().insert(new BufferingDecorator(outputMessage), context)).build()
            );
        } else {
            return next.exchange(request);
        }
    }

    private static final class BufferingDecorator extends ClientHttpRequestDecorator {

        private BufferingDecorator(ClientHttpRequest delegate) {
            super(delegate);
        }

        @Override
        public Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
            return DataBufferUtils.join(body).flatMap(buffer -> {
                getHeaders().setContentLength(buffer.readableByteCount());
                return super.writeWith(Mono.just(buffer));
            });
        }
    }
}

class MultipartExchangeFilterFunction : ExchangeFilterFunction {

    override fun filter(request: ClientRequest, next: ExchangeFunction): Mono<ClientResponse> {
        return if (MediaType.MULTIPART_FORM_DATA.includes(request.headers().getContentType())
            && (request.method() == HttpMethod.PUT || request.method() == HttpMethod.POST)) {
            next.exchange(ClientRequest.from(request)
                .body { message, context -> request.body().insert(BufferingDecorator(message), context) }
                .build())
        }
        else {
            next.exchange(request)
        }

    }

    private class BufferingDecorator(delegate: ClientHttpRequest) : ClientHttpRequestDecorator(delegate) {
        override fun writeWith(body: Publisher<out DataBuffer>): Mono<Void> {
            return DataBufferUtils.join(body)
                .flatMap {
                    headers.contentLength = it.readableByteCount().toLong()
                    super.writeWith(Mono.just(it))
                }
        }
    }
}