spring 5 webclient使用指南

序

之前写了一篇restTemplate使用实例，由于spring 5全面引入reactive，同时也有了restTemplate的reactive版webclient，本文就来对应展示下webclient的基本使用。

请求携带header

• 携带cookie @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()); }
• 携带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()); }
• 设置全局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请求

• 使用placeholder传递参数 @Test public void testUrlPlaceholder(){ Mono<String> resp = WebClient.create() .get() //多个参数也可以直接放到map中,参数名与placeholder对应上即可 .uri("http://www.baidu.com/s?wd={key}&other={another}","北京天气","test") //使用占位符 .retrieve() .bodyToMono(String.class); LOGGER.info("result:{}",resp.block()); }
• 使用uriBuilder传递参数 @Test public void testUrlBiulder(){ Mono<String> 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); LOGGER.info("result:{}",resp.block()); }

post表单

    @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

• 使用bean来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()); }
• 直接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二进制—上传文件

    @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());
    }

下载二进制

• 下载图片 @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")); }
• 下载文件 @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()); }

错误处理

    @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);
    }

• 可以使用onStatus根据status code进行异常适配
• 可以使用doOnError异常适配
• 可以使用onErrorReturn返回默认值

小结

webclient是新一代的async rest template，api也相对简洁，而且是reactive的，非常值得使用。

doc

• restTemplate使用实例
• Decode ByteArray with spring 5 WebFlux framework