WebClient

Spring 有两个web客户端的实现，一个是RestTemplate另一个是spring5的响应代替WebClient。

WebClient是一个以Reactive方式处理HTTP请求的非阻塞客户端。

  • RestTemplate是阻塞客户端

    • 它基于thread-pre-requset模型。
    • 这意味着线程将阻塞，直到 Web 客户端收到响应。阻塞代码的问题是由于每个线程消耗了一些内存和 CPU 周期。当出现慢速请求的时候，等待结果的线程会堆积起来，将导致创建更多的线程、消耗更多的资源。频繁切换CPU资源也会降低性能。

  • WebClient是异步、非阻塞的方案。

    • WebClient将为每个事件创建类似于“任务”的东西。在幕后，Reactive 框架会将这些“任务”排队并仅在适当的响应可用时执行它们。

    • WebClient是Spring WebFlux库的一部分。因此，我们还可以使用具有反应类型（Mono和Flux的功能性、流畅的 API 作为声明性组合来编写客户端代码。

    • 底层支持的库

      • Reactor Netty - ReactorClientHttpConnector
      • Jetty ReactiveStream HttpClient - JettyHttpConnector

  • 关于IDEA开启 Reactive Streams DEBUG

演示代码

基础用法

创建WebClient

WebClient.create();
WebClient.builder();

请求方法

   WebClient webClient =   WebClient.create();
        webClient.get();
        webClient.post();
        webClient.delete();
        webClient.put();
        webClient.patch();
        webClient.options();

获取结果

// exchangeToMono方法 
// exchangeToFlux方法
Mono<Object> entityMono = webClient.get()
                .uri("/persons/1")
                .accept(MediaType.APPLICATION_JSON)
                .exchangeToMono(response -> {
                    if (response.statusCode().equals(HttpStatus.OK)) {
                        return response.bodyToMono(Object.class);
                    } else if (response.statusCode().is4xxClientError()) {
                        return response.bodyToMono(Object.class);
                    } else {
                        return Mono.error((Supplier<? extends Throwable>) response.createException());
                    }
                });

        Flux<Object> entityFlux = webClient.get()
                .uri("/persons")
                .accept(MediaType.APPLICATION_JSON)
                .exchangeToFlux(response -> {
                    if (response.statusCode().equals(HttpStatus.OK)) {
                        return response.bodyToFlux(Object.class);
                    } else if (response.statusCode().is4xxClientError()) {
                        return response.bodyToMono(Object.class).flux();
                    } else {
                        return Flux.error((Supplier<? extends Throwable>) response.createException());
                    }
                });

异常处理

   .doOnError(t -> log.error("Error: ", t)) // 异常回调
   .doFinally(s -> log.info("Finally ")) // Finally 回调

请求体

// 直接使用bodyValue方法
RequestHeadersSpec<?> headersSpec = bodySpec.bodyValue("data");
// 或者Publisher
RequestHeadersSpec<?> headersSpec = bodySpec.body(Mono.just(new Foo("name")), Foo.class);

代码演示

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
public class AppApplication {

    public static void main(String[] args) {
        ApplicationContext applicationContext = SpringApplication.run(AppApplication.class, args);
    }
    // 声明默认的WebClient
    @Bean
    public WebClient register() {
        return WebClient.create();
    }
}

@RestController
@RequestMapping("/")
@Slf4j
public class AppController {

    @Autowired
    private WebClient webClient;

    @PostMapping("/list")
    public Flux<UserVo> list() {
        List<UserVo> userList = new ArrayList<>();
        userList.add(new UserVo("1", "张三"));
        userList.add(new UserVo("2", "王五"));
        return Flux.fromIterable(userList);
    }

    @GetMapping("/{id}")
    public Mono<UserVo> info(@PathVariable(value = "id") String id) {
        return Mono.just(new UserVo(id, "某某"));
    }

    @GetMapping("/ip/info")
    public Mono<String> ip() {
        String url = "https://myip.ipip.net/";
        Mono<String> body = webClient.get()
                .uri(url)
                .header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE) // 响应的格式json
                .acceptCharset(StandardCharsets.UTF_8) // 编码集 utf-8
                .exchangeToMono(response -> {
                    if (response.statusCode().equals(HttpStatus.OK)) {
                        return response.bodyToMono(String.class);
                    } else {
                        return response.createException().flatMap(Mono::error);
                    }
                })
                .doOnError(t -> log.error("Error: ", t)) // 异常回调
                .doFinally(s -> log.error("Finally ")) // Finally 回调
                .subscribeOn(Schedulers.single());
        return body;
    }

}

@Data
@AllArgsConstructor
@NoArgsConstructor
public class UserVo {

    private String uid;

    private String name;
}

接口Mock测试

  • 添加@WebFluxTest注解
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@BootstrapWith(WebFluxTestContextBootstrapper.class)
@ExtendWith(SpringExtension.class)
@OverrideAutoConfiguration(enabled = false)
@TypeExcludeFilters(WebFluxTypeExcludeFilter.class)
@AutoConfigureCache
@AutoConfigureJson
@AutoConfigureWebFlux // 自动装配WebFlux
@AutoConfigureWebTestClient // 自动装配WebTestClient
@ImportAutoConfiguration
public @interface WebFluxTest {
  • 代码
@Slf4j
@ExtendWith(SpringExtension.class)
@ActiveProfiles("dev")
@WebFluxTest
public class AppApplicationMockTest {

    @Autowired
    private WebTestClient webTestClient;

    @MockBean
    private AppController appController;

    @Test
    @Disabled
    public void get() {
        UserVo user = new UserVo("1", "张三");
        Mockito.when(appController.info("1")).thenReturn(Mono.just(user));
        EntityExchangeResult<UserVo> result = webTestClient.get()
                .uri("/1")
                .exchange()
                .expectStatus().isOk()
                .expectBody(UserVo.class)
                .returnResult();
        log.info("{}", result);
    }

    @Test
    @Disabled
    public void list() {
        List<UserVo> userList = new ArrayList<>();
        userList.add(new UserVo("1", "张三"));
        userList.add(new UserVo("2", "王武"));
        Mockito.when(appController.list()).thenReturn(Flux.fromIterable(userList));
        EntityExchangeResult<List<UserVo>> result = webTestClient.post()
                .uri("/list")
                .exchange()
                .expectStatus().isOk()
                .expectBodyList(UserVo.class)
                .returnResult();
        log.info("{}", result);
    }

}
  • Console
[main]  
> GET /1
> WebTestClient-Request-Id: [1]

No content

< 200 OK OK
< Content-Type: [application/json]
< Content-Length: [27]

{"uid":"1","name":"张三"}

[main]  
> POST /list
> WebTestClient-Request-Id: [1]

No content

< 200 OK OK
< Content-Type: [application/json]

[{"uid":"1","name":"张三"},{"uid":"2","name":"王武"}]

接口测试

  • 添加@AutoConfigureWebTestClient 启用WebTestClient。
@Slf4j
@ExtendWith(SpringExtension.class)
@SpringBootTest(classes = AppApplication.class, webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@ActiveProfiles("dev")
@AutoConfigureWebTestClient
public class AppApplicationTest {

    @Autowired
    private WebTestClient webTestClient;

    @Test
    @Disabled
    public void get() {
        EntityExchangeResult<UserVo> result = webTestClient.get()
                .uri("/1")
                .exchange()
                .expectStatus().isOk()
                .expectBody(UserVo.class)
                .returnResult();
        log.info("{}", result);
    }

    @Test
    @Disabled
    public void ip() {
        EntityExchangeResult<String> result = webTestClient.get()
                .uri("/ip/info")
                .exchange()
                .expectStatus().isOk()
                .expectBody(String.class)
                .returnResult();
        log.info("{}", result);
    }

    @Test
    @Disabled
    public void list() {
        EntityExchangeResult<List<UserVo>> result = webTestClient.post()
                .uri("/list")
                .exchange()
                .expectStatus().isOk()
                .expectBodyList(UserVo.class)
                .returnResult();
        log.info("{}", result);
    }

}
  • Console
[main]  
> GET /1
> WebTestClient-Request-Id: [1]

No content

< 200 OK OK
< Content-Type: [application/json]
< Content-Length: [27]

{"uid":"1","name":"某某"}

[reactor-http-nio-3]  Finally 
[main]  
> GET /ip/info
> WebTestClient-Request-Id: [1]

No content

< 200 OK OK
< Content-Type: [text/plain;charset=UTF-8]
< Content-Length: [67]

当前 IP：000.000.00.0  来自于：中国 浙江 杭州  电信

[main]  
> POST /list
> WebTestClient-Request-Id: [1]

No content

< 200 OK OK
< Content-Type: [application/json]

[{"uid":"1","name":"张三"},{"uid":"2","name":"王五"}]

END

Last Updated:
Contributors: 庆峰