spring5 webclient使用指南详解

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);
  }

1. 可以使用onStatus根据status code进行异常适配
2. 可以使用doOnError异常适配
3. 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。

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持我们。

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