Spring5.0 — WebClient（响应式web客户端）

一、介绍

1.1、RestTemplate 

同步阻塞代码，http 请求返回响应才继续执行。

1.2、WebClient 

1.基于 Reactindex.php/tags-1038.html" >or 和 Netty。

2.响应式 web 客户端。异步执行不阻塞代码，少量的线程数处理高并发的 Http 请求。

3.集成 Spring WebFlux 框架，可与其他 Spring 组件无缝协作。

4.可通过自定义 ExchangeFilterFunction 对请求和响应进行拦截和处理。

二、使用 

2.1、引入依赖 

    org.springframework.boot    spring-boot-starter-webflux

2.2、基础属性介绍

2.2.1、基础配置

HTTP 底库// 选择 HTTP 底库; 默认底层用Netty，切换Jetty。WebClient         .builder()         .clientConnector(new JettyClientHttpConnector()) .build();全局的请求配置// 设置基础的全局的web请求配置，如cookie、header、baseUrl。WebClient.builder().defaultCookie("kl","kl").defaultUriVariables(ImmutableMap.of("name","kl")).defaultHeader("header","kl").defaultHeaders(httpHeaders -> {httpHeaders.add("header1","kl");httpHeaders.add("header2","kl");}).defaultCookies(cookie ->{cookie.add("cookie1","kl");cookie.add("cookie2","kl");}).baseUrl("http://www.kailing.pub").build();Filter// Filter 过滤器，统一修改拦截请求。WebClient.builder().baseUrl("http://www.kailing.pub").filter((request, next) -> {ClientRequest filtered = ClientRequest.from(request).header("foo", "bar").build();return next.exchange(filtered);}).filters(filters ->{filters.add(ExchangeFilterFunctions.basicAuthentication("username","password"));filters.add(ExchangeFilterFunctions.limitResponseSize(800));}).build().get().uri("/article/index/arcid/{id}.html", 254).retrieve().bodyToMono(String.class).subscribe(System.err::println);Netty 库配置 // 配置动态连接池 ConnectionProvider provider = ConnectionProvider.elastic("elastic pool"); 配置固定大小连接池，如最大连接数、连接获取超时、空闲连接***亡时间等ConnectionProvider provider = ConnectionProvider.fixed("fixed", 45, 4000, Duration.ofSeconds(6));HttpClient httpClient = HttpClient.create(provider).secure(sslContextSpec -> {SslContextBuilder sslContextBuilder = SslContextBuilder.forClient().trustManager(new File("E://server.truststore"));sslContextSpec.sslContext(sslContextBuilder);}).tcpConfiguration(tcpClient -> {// 指定Netty的 select 和 work 线程数量LoopResources loop = LoopResources.create("kl-event-loop", 1, 4, true);return tcpClient.doOnConnected(connection -> {// 读写超时设置connection.addHandlerLast(new ReadTimeoutHandler(10, TimeUnit.SECONDS)).addHandlerLast(new WriteTimeoutHandler(10));})// 连接超时设置   .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 10000)   .option(ChannelOption.TCP_NODELAY, true)   .runOn(loop);});WebClient.builder().clientConnector(new ReactorClientHttpConnector(httpClient)).build();

2.2.2、WebClient.builder() 的选项

uriBuilderFactory：自定义UriBuilderFactory用作基本URL(BaseUrl)。defaultHeader：每个请求的标题。defaultCookie：针对每个请求的Cookie。defaultRequest：Consumer自定义每个请求。filter：针对每个请求的客户端过滤器。exchangeStrategies：HTTP消息读取器/写入器定制。clientConnector：HTTP客户端库设置。

2.2.3、请求类型、与返回结果

.block()   阻塞当前程序等待结果.retrieve()   直接获取响应body.exchange()   可访问整个ClientResponse

2.3、get 请求

// 简单传参。默认异步，通过 Mono 的 subscribe 订阅响应值。block() 阻塞当前线程获取返回值。WebClient client = WebClient.create("http://www.kailing.pub");Mono result = client.get().uri("/article/arcid/{id}", 256).acceptCharset(StandardCharsets.UTF_8).accept(MediaType.TEXT_HTML).retrieve()     // 同步.bodyToMono(String.class);result.subscribe(System.err::println);// 复杂传参 — MultiValueMap。默认异步，通过 Mono 的 subscribe 订阅响应值。block() 阻塞当前线程获取返回值。MultiValueMap params = new LinkedMultiValueMap();params.add("name", "kl");params.add("age", "19");// 定义 url 参数 Map uriVariables = new HashMap(); uriVariables.put("id", 200);String uri = UriComponentsBuilder.fromUriString("/article/arcid/{id}").queryParams(params).uriVariables(uriVariables).toUriString();Mono result = client.get().uri(uri).acceptCharset(StandardCharsets.UTF_8).accept(MediaType.TEXT_HTML).retrieve().bodyToMono(String.class);result.subscribe(System.err::println);// 复杂传参 — UriBuilder。默认异步，通过 Mono 的 subscribe 订阅响应值。block() 阻塞当前线程获取返回值。Mono resp = WebClient.create().get().uri(uriBuilder -> uriBuilder.scheme("http").host("www.baidu.com").path("/s").queryParam("wd", "北京天气").queryParam("other", "test").build()).retrieve().bodyToMono(String.class);

2.4、post 请求

// 表单 默认异步，通过 Mono 的 subscribe 订阅响应值。block() 阻塞当前线程获取返回值。MultiValueMap formData = new LinkedMultiValueMap();formData.add("name1","value1");formData.add("name2","value2");Mono resp = WebClient.create().post().uri("http://www.w3school.com.cn/test/demo_form.asp").contentType(MediaType.APPLICATION_FORM_URLENCODED).body(BodyInserters.fromFormData(formData)).retrieve().bodyToMono(String.class);LOGGER.info("result:{}",resp.block());// FormInserter  表单：参数、文件。默认异步，通过 Mono 的 subscribe 订阅响应值。block() 阻塞当前线程获取返回值。WebClient client = WebClient.create("http://www.kailing.pub");FormInserter formInserter = fromMultipartData("name","kl").with("age",19).with("map",ImmutableMap.of("xx","xx")).with("file",new File("C://xxx.doc"));Mono result = client.post().uri("/article/index/arcid/{id}.html", 256).contentType(MediaType.APPLICATION_JSON).body(formInserter)//.bodyValue(ImmutableMap.of("name","kl")).retrieve().bodyToMono(String.class);result.subscribe(System.err::println);// json — 实体类。默认异步，通过 Mono 的 subscribe 订阅响应值。block() 阻塞当前线程获取返回值。User user = new User();user.setName("aaa");user.setTitle("AAAAAA");Mono resp = WebClient.create()    .post().uri("http://localhost:8080/demo/json").contentType(MediaType.APPLICATION_JSON_UTF8).body(Mono.just(user),User.class).retrieve().bodyToMono(String.class);System.out.println("---resp.block(): "+resp.block());// json — raw。默认异步，通过 Mono 的 subscribe 订阅响应值。block() 阻塞当前线程获取返回值。Mono resp = WebClient.create().post().uri("http://localhost:8080/demo/json").contentType(MediaType.APPLICATION_JSON_UTF8).body(BodyInserters.fromObject("{\n" +"  \"title\" : \"this is title\",\n" +"  \"author\" : \"this is author\"\n" +"}")).retrieve().bodyToMono(String.class);System.out.println("---resp.block(): "+resp.block());// 二进制上传文件HttpHeaders headers = new HttpHeaders();headers.setContentType(MediaType.IMAGE_PNG);HttpEntity entity = new HttpEntity(new ClassPathResource("parallel.png"), headers);MultiValueMap parts = new LinkedMultiValueMap();parts.add("file", entity);Mono resp = WebClient.create().post().uri("http://localhost:8080/upload").contentType(MediaType.MULTIPART_FORM_DATA).body(BodyInserters.fromMultipartData(parts)).retrieve().bodyToMono(String.class);System.out.println("---resp.block(): "+resp.block());

2.5、WebSocketClient  使用 Socket

WebSocketClient client = new ReactorNettyWebSocketClient();URI url = new URI("ws://localhost:8080/path");client.execute(url, session ->session.receive().doOnNext(System.out::println).then());

三、封装工具类 

import org.springframework.http.HttpHeaders;import org.springframework.http.MediaType;import org.springframework.web.reactive.function.BodyInserters;import org.springframework.web.reactive.function.client.WebClient;import reactor.core.publisher.Mono;/** *  */public class WebClientUtils {        private WebClient webClient;    public WebClientUtils(String baseUrl) {        this.webClient = WebClient.builder()                .baseUrl(baseUrl)                .defaultHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE).filter(logRequest())                .build();    }    public  Mono get(String uri, Class responseType) {        return webClient.get()                .uri(uri)                .retrieve()                .bodyToMono(responseType);    }    public  Mono post(String uri, Object request, Class responseType) {        return webClient.post()                .uri(uri)                .body(BodyInserters.fromValue(request))                .retrieve()                .bodyToMono(responseType);    }    public  Mono put(String uri, Object request, Class responseType) {        return webClient.put()                .uri(uri)                .body(BodyInserters.fromValue(request))                .retrieve()                .bodyToMono(responseType);    }    public  Mono delete(String uri, Class responseType) {        return webClient.delete()                .uri(uri)                .retrieve()                .bodyToMono(responseType);    }private ExchangeFilterFunction logRequest() {    return (clientRequest, next) -> {        logger.info("Request: {} {}", clientRequest.method(), clientRequest.url());clientRequest.headers().forEach((name, values) -> values.forEach(value -> logger.info("{}={}", name, value)));        return next.exchange(clientRequest);};}}public class Test001 {    public static void main(String[] args) {        WebClientUtils webClientUtils = new WebClientUtils("https://api.example.com");        // 发起 GET 请求        webClientUtils.get("/users/1", User.class).subscribe(user -> System.out.println("GET response: " + user));        // 发起 POST 请求        User newUser = new User("John", "Doe");        webClientUtils.post("/users", newUser, User.class).subscribe(user -> System.out.println("POST response: " + user));        // 发起 PUT 请求        User updatedUser = new User("Jane", "Doe");        webClientUtils.put("/users/1", updatedUser, User.class).subscribe(user -> System.out.println("PUT response: " + user));        // 发起 DELETE 请求        webClientUtils.delete("/users/1", Void.class).subscribe(response -> System.out.println("DELETE response: " + response));    }}