Detailed explanation of spring5 webclient usage guide

I have written an example of restTemplate usage. Since spring 5 fully introduces reactive and also has a reactive version of restTemplate's webclient, this article will show the basic use of webclient.

Request to carry header

Carry cookies

 @Test public void testWithCookie(){ Mono<String> resp = WebClient.create() .method(HttpMethod.GET) .uri("http://baidu.com") .cookie("token","xxxx") .cookie("JSESSIONID","XXXX") .retrieve() .bodyToMono(String.class); LOGGER.info("result:{}",resp.block()); }

Carry basic auth

 @Test public void testWithBasicAuth(){ String basicAuth = "Basic "+ Base64.getEncoder().encodeToString("user:pwd".getBytes(StandardCharsets.UTF_8)); LOGGER.info(basicAuth); Mono<String> resp = WebClient.create() .get() .uri("http://baidu.com") .header(HttpHeaders.AUTHORIZATION,basicAuth) .retrieve() .bodyToMono(String.class); LOGGER.info("result:{}",resp.block()); }

Set global user-agent

 @Test public void testWithHeaderFilter(){ WebClient webClient = WebClient.builder() .defaultHeader(HttpHeaders.USER_AGENT, "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_6) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/63.0.3239.132 Safari/537.36") .filter(ExchangeFilterFunctions .basicAuthentication("user","password")) .filter((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); }) .build(); Mono<String> resp = webClient.get() .uri("https://baidu.com") .retrieve() .bodyToMono(String.class); LOGGER.info("result:{}",resp.block()); }

get request

Pass parameters using placeholder

 @Test public void testUrlPlaceholder(){ Mono<String> resp = WebClient.create() .get() // Multiple parameters can also be placed directly in the map, and the parameter name corresponds to the placeholder.uri("http://www.baidu.com/s?wd={key}&other={another}","Beijing Weather","test") //Use placeholder.retrieve() .bodyToMono(String.class); LOGGER.info("result:{}",resp.block()); }

Pass parameters using uriBuilder

 @Test public void testUrlBiulder(){ Mono<String> resp = WebClient.create() .get() .uri(uriBuilder -> uriBuilder .scheme("http") .host("www.baidu.com") .path("/s") .queryParam("wd", "Beijing Weather") .queryParam("other", "test") .build()) .retrieve() .bodyToMono(String.class); LOGGER.info("result:{}",resp.block()); }

Post form

 @Test public void testFormParam(){ MultiValueMap<String, String> formData = new LinkedMultiValueMap<>(); formData.add("name1","value1"); formData.add("name2","value2"); Mono<String> 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()); }

post json

Use beans to post

 static class Book { String name; String title; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getTitle() { return title; } public void setTitle(String title) { this.title = title; } } @Test public void testPostJson(){ Book book = new Book(); book.setName("name"); book.setTitle("this is title"); Mono<String> resp = WebClient.create().post() .uri("http://localhost:8080/demo/json") .contentType(MediaType.APPLICATION_JSON_UTF8) .body(Mono.just(book),Book.class) .retrieve().bodyToMono(String.class); LOGGER.info("result:{}",resp.block()); }

Direct post raw json

 @Test public void testPostRawJson(){ Mono<String> 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); LOGGER.info("result:{}",resp.block()); }

post binary-upload file

 @Test public void testUploadFile(){ HttpHeaders headers = new HttpHeaders(); headers.setContentType(MediaType.IMAGE_PNG); HttpEntity<ClassPathResource> entity = new HttpEntity<>(new ClassPathResource("parallel.png"), headers); MultiValueMap<String, Object> parts = new LinkedMultiValueMap<>(); parts.add("file", entity); Mono<String> resp = WebClient.create().post() .uri("http://localhost:8080/upload") .contentType(MediaType.MULTIPART_FORM_DATA) .body(BodyInserters.fromMultipartData(parts)) .retrieve().bodyToMono(String.class); LOGGER.info("result:{}",resp.block()); }

Download binary

Download the picture

 @Test public void testDownloadImage() throws IOException { Mono<Resource> resp = WebClient.create().get() .uri("http://www.toolip.gr/captcha?complexity=99&size=60&length=9") .accept(MediaType.IMAGE_PNG) .retrieve().bodyToMono(Resource.class); Resource resource = resp.block(); BufferedImage bufferedImage = ImageIO.read(resource.getInputStream()); ImageIO.write(bufferedImage, "png", new File("captcha.png")); }

Download the file

 @Test public void testDownloadFile() throws IOException { Mono<ClientResponse> resp = WebClient.create().get() .uri("http://localhost:8080/file/download") .accept(MediaType.APPLICATION_OCTET_STREAM) .exchange(); ClientResponse response = resp.block(); String disposition = response.headers().asHttpHeaders().getFirst(HttpHeaders.CONTENT_DISPOSITION); String fileName = disposition.substring(disposition.indexOf("=")+1); Resource resource = response.bodyToMono(Resource.class).block(); File out = new File(fileName); FileUtils.copyInputStreamToFile(resource.getInputStream(),out); LOGGER.info(out.getAbsolutePath()); }

Error handling

 @Test public void testRetrieve4xx(){ WebClient webClient = WebClient.builder() .baseUrl("https://api.github.com") .defaultHeader(HttpHeaders.CONTENT_TYPE, "application/vnd.github.v3+json") .defaultHeader(HttpHeaders.USER_AGENT, "Spring 5 WebClient") .build(); WebClient.ResponseSpec responseSpec = webClient.method(HttpMethod.GET) .uri("/user/repos?sort={sortField}&direction={sortDirection}", "updated", "desc") .retrieve(); Mono<String> mono = responseSpec .onStatus(e -> e.is4xxClientError(),resp -> { LOGGER.error("error:{},msg:{}",resp.statusCode().value(),resp.statusCode().getReasonPhrase()); return Mono.error(new RuntimeException(resp.statusCode().value() + " : " + resp.statusCode().getReasonPhrase())); }) .bodyToMono(String.class) .doOnError(WebClientResponseException.class, err -> { LOGGER.info("ERROR status:{},msg:{}",err.getRawStatusCode(),err.getResponseBodyAsString()); throw new RuntimeException(err.getMessage()); }) .onErrorReturn("fallback"); String result = mono.block(); LOGGER.info("result:{}",result); }

1. You can use onStatus to perform exception adaptation according to status code
2. Can use doOnError exception adaptation
3. You can use onErrorReturn to return the default value

summary

Webclient is a new generation of async rest template, and the API is relatively simple and reactive, which is very worth using.

The above is all the content of this article. I hope it will be helpful to everyone's learning and I hope everyone will support Wulin.com more.