webclient对reactor-netty的封装

2018-02-27 11:50:45来源:oschina作者:go4it人点击

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本文主要研究一下spring 5的WebClient对reactor-netty的HttpClient的封装


DefaultWebClientBuilder

spring-webflux-5.0.2.RELEASE-sources.jar!/org/springframework/web/reactive/function/client/DefaultWebClientBuilder.java


@Override
public WebClient build() {
ExchangeFunction exchange = initExchangeFunction();
ExchangeFunction filteredExchange = (this.filters != null ? this.filters.stream()
.reduce(ExchangeFilterFunction::andThen)
.map(filter -> filter.apply(exchange))
.orElse(exchange) : exchange);
return new DefaultWebClient(filteredExchange, initUriBuilderFactory(),
unmodifiableCopy(this.defaultHeaders), unmodifiableCopy(this.defaultCookies),
new DefaultWebClientBuilder(this));
}

这里的build调用了initExchangeFunction方法



private ExchangeFunction initExchangeFunction() {
if (this.exchangeFunction != null) {
return this.exchangeFunction;
}
else if (this.connector != null) {
return ExchangeFunctions.create(this.connector, this.exchangeStrategies);
}
else {
return ExchangeFunctions.create(new ReactorClientHttpConnector(), this.exchangeStrategies);
}
}

这里new了一个ReactorClientHttpConnector



ReactorClientHttpConnector

spring-web-5.0.2.RELEASE-sources.jar!/org/springframework/http/client/reactive/ReactorClientHttpConnector.java


/**
* Create a Reactor Netty {@link ClientHttpConnector}
* with default {@link ClientOptions} and HTTP compression support enabled.
*/
public ReactorClientHttpConnector() {
this.httpClient = HttpClient.builder()
.options(options -> options.compression(true))
.build();
}

可以看到这个构造器使用了reactor/ipc/netty/http/client/HttpClient



DefaultWebClient

spring-webflux-5.0.2.RELEASE-sources.jar!/org/springframework/web/reactive/function/client/DefaultWebClient.java


@Override
public RequestHeadersUriSpec<?> get() {
return methodInternal(HttpMethod.GET);
}
@Override
public RequestHeadersUriSpec<?> head() {
return methodInternal(HttpMethod.HEAD);
}
@Override
public RequestBodyUriSpec post() {
return methodInternal(HttpMethod.POST);
}
@Override
public RequestBodyUriSpec put() {
return methodInternal(HttpMethod.PUT);
}
@Override
public RequestBodyUriSpec patch() {
return methodInternal(HttpMethod.PATCH);
}
@Override
public RequestHeadersUriSpec<?> delete() {
return methodInternal(HttpMethod.DELETE);
}
@Override
public RequestHeadersUriSpec<?> options() {
return methodInternal(HttpMethod.OPTIONS);
}
@Override
public RequestBodyUriSpec method(HttpMethod httpMethod) {
return methodInternal(httpMethod);
}
@SuppressWarnings("unchecked")
private RequestBodyUriSpec methodInternal(HttpMethod httpMethod) {
return new DefaultRequestBodyUriSpec(httpMethod);
}

DefaultWebClient主要对GET、HEAD、POST、PUT、PATCH、DELETE、OPTIONS方法封装返回RequestHeadersUriSpec或者RequestBodyUriSpec



@Override
public Mono exchange() {
ClientRequest request = (this.inserter != null ?
initRequestBuilder().body(this.inserter).build() :
initRequestBuilder().build());
return exchangeFunction.exchange(request).switchIfEmpty(NO_HTTP_CLIENT_RESPONSE_ERROR);
}

最后在exchange方法里头封装了对exchangeFunction的调用,这里的switchIfEmpty返回的是reactor.core.publisher.MonoSwitchIfEmpty



spring-webflux-5.0.2.RELEASE-sources.jar!/org/springframework/web/reactive/function/client/ExchangeFunctions.java


public Mono exchange(ClientRequest request) {
Assert.notNull(request, "'request' must not be null");
return this.connector
.connect(request.method(), request.url(),
clientHttpRequest -> request.writeTo(clientHttpRequest, this.strategies))
.log("org.springframework.web.reactive.function.client", Level.FINE)
.map(clientHttpResponse -> new DefaultClientResponse(clientHttpResponse,
this.strategies));
}

这里调用了ReactorClientHttpConnector的connect方法



spring-web-5.0.2.RELEASE-sources.jar!/org/springframework/http/client/reactive/ReactorClientHttpConnector.java


public Mono connect(HttpMethod method, URI uri,
Function<? super ClientHttpRequest, Mono> requestCallback) {
if (!uri.isAbsolute()) {
return Mono.error(new IllegalArgumentException("URI is not absolute: " + uri));
}
return this.httpClient
.request(adaptHttpMethod(method),
uri.toString(),
request -> requestCallback.apply(adaptRequest(method, uri, request)))
.map(this::adaptResponse);
}

connect方法最后调用的reactor-netty的HttpClient的request方法。



小结

spring 5的webflux部分主要基于reactor项目来的,WebClient也是基于reactor-netty来实现,主要是封装了一些UriSpec及其他便利方法。



接口见spring-webflux-5.0.2.RELEASE-sources.jar!/org/springframework/web/reactive/function/client/WebClient.java


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