SpringBoot 3.2引入了新的 RestClient 用于http接口调用,采用了 fluent API 的风格,可以进行链式调用。
具体的代码参照 示例项目 https://github.com/qihaiyan/springcamp/tree/master/spring-jdbc-client
一、概述
RestClient 是一个类似于 RestTemplate 的的同步接口调用工具。相比于 RestTemplate 采用的是 template 设计模式,RestClient 采用了 fluent API 风格,简单灵活,易于阅读和维护。
二、引入 RestClient
首先引入 spring-boot-starter-web 依赖。
在 build.gradle 中增加一行代码:
groovy
implementation 'org.springframework.boot:spring-boot-starter-web'
对 RestClient 进行配置:
java
@Configuration
public class RestClientConfig {
public CloseableHttpClient httpClient() {
Registry<ConnectionSocketFactory> registry =
RegistryBuilder.<ConnectionSocketFactory>create()
.register("http", PlainConnectionSocketFactory.getSocketFactory())
.register("https", SSLConnectionSocketFactory.getSocketFactory())
.build();
PoolingHttpClientConnectionManager poolingConnectionManager = new PoolingHttpClientConnectionManager(registry);
poolingConnectionManager.setDefaultSocketConfig(SocketConfig.custom().setSoTimeout(Timeout.ofSeconds(2)).build());
poolingConnectionManager.setDefaultConnectionConfig(ConnectionConfig.custom().setConnectTimeout(Timeout.ofSeconds(2)).build());
// set total amount of connections across all HTTP routes
poolingConnectionManager.setMaxTotal(200);
// set maximum amount of connections for each http route in pool
poolingConnectionManager.setDefaultMaxPerRoute(200);
RequestConfig requestConfig = RequestConfig.custom()
.setConnectionKeepAlive(TimeValue.ofSeconds(10))
.setConnectionRequestTimeout(Timeout.ofSeconds(2))
.setResponseTimeout(Timeout.ofSeconds(2))
.build();
return HttpClients.custom()
.setDefaultRequestConfig(requestConfig)
.setConnectionManager(poolingConnectionManager)
.setKeepAliveStrategy(new DefaultConnectionKeepAliveStrategy())
.build();
}
@Slf4j
static class CustomClientHttpRequestInterceptor implements ClientHttpRequestInterceptor {
@Override
@NonNull
public ClientHttpResponse intercept(HttpRequest request, @NonNull byte[] bytes, @NonNull ClientHttpRequestExecution execution) throws IOException {
log.info("HTTP Method: {}, URI: {}, Headers: {}", request.getMethod(), request.getURI(), request.getHeaders());
request.getMethod();
if (request.getMethod().equals(HttpMethod.POST)) {
log.info("HTTP body: {}", new String(bytes, StandardCharsets.UTF_8));
}
ClientHttpResponse response = execution.execute(request, bytes);
ClientHttpResponse responseWrapper = new BufferingClientHttpResponseWrapper(response);
String body = StreamUtils.copyToString(responseWrapper.getBody(), StandardCharsets.UTF_8);
log.info("RESPONSE body: {}", body);
return responseWrapper;
}
}
static class BufferingClientHttpResponseWrapper implements ClientHttpResponse {
private final ClientHttpResponse response;
private byte[] body;
BufferingClientHttpResponseWrapper(ClientHttpResponse response) {
this.response = response;
}
@NonNull
public HttpStatusCode getStatusCode() throws IOException {
return this.response.getStatusCode();
}
@NonNull
public String getStatusText() throws IOException {
return this.response.getStatusText();
}
@NonNull
public HttpHeaders getHeaders() {
return this.response.getHeaders();
}
@NonNull
public InputStream getBody() throws IOException {
if (this.body == null) {
this.body = StreamUtils.copyToByteArray(this.response.getBody());
}
return new ByteArrayInputStream(this.body);
}
public void close() {
this.response.close();
}
}
@Bean
public RestTemplate restTemplate(RestTemplateBuilder builder) {
return builder
.requestFactory(() -> new HttpComponentsClientHttpRequestFactory(httpClient()))
.interceptors(new CustomClientHttpRequestInterceptor())
.build();
}
@Bean
public RestClient restClient(RestTemplate restTemplate) {
return RestClient.builder(restTemplate).requestFactory(new HttpComponentsClientHttpRequestFactory(httpClient())).build();
}
}
在配置中我们仍然定义了 RestTemplate ,并使用 RestTemplate 来初始化 RestClient 为的是继续使用 RestTemplate 的日志打印功能 参照 https://github.com/qihaiyan/springcamp/tree/master/spring-rest-template-log
如果不想继续使用RestTemplate,那初始化代码可以改为
java
RestClient.builder().requestFactory(new HttpComponentsClientHttpRequestFactory(httpClient())).build();
同时我们给 RestClient 配置了 requestFactory ,可以使用长连接调用接口。
三、GET接口调用
调用GET接口返回字符串:
java
restClient.get()
.uri("https://httpbin.org/get")
.retrieve()
.body(String.class)
调用GET接口对象:
java
restClient.get()
.uri("https://httpbin.org/get")
.retrieve()
.body(MyData.class);
调用GET接口返回List:
java
List<String> list = restClient.get()
.uri("http://someservice/list")
.retrieve()
.body(new ParameterizedTypeReference<>() {});
四、POST接口调用
java
MyData postBody = new MyData("test", "test RestClient");
ResponseEntity<String> respObj = restClient.post()
.uri("https://httpbin.org/post")
.contentType(MediaType.APPLICATION_JSON)
.body(postBody)
.retrieve()
.toEntity(String.class);
五、Exchange接口调用
当需要对接口返回结果进行更加精确的控制时,可以采用 Exchange 方法。
例如当接口返回 4xx 时,让 restClient 返回空字符串,否则返回正常结果:
java
restClient.get()
.uri("https://httpbin.org/get")
.accept(MediaType.APPLICATION_JSON)
.exchange((request, response) -> {
if (response.getStatusCode().is4xxClientError()) {
log.info("status 4xx");
return "";
} else {
log.info("response: {}", response);
return response;
}
});
六、错误处理
当接口返回错误时,可以在 onStatus 方法中进行判断并进行对应的操作:
java
restClient.get()
.uri("https://httpbin.org/status/404")
.retrieve()
.onStatus(status -> status.value() == 404, (request, response) -> {
log.info("status 404");
})
.toBodilessEntity();
toBodilessEntity 方法是一种忽略接口返回结果的方法,当不需要读取接口返回结果时,可以使用 toBodilessEntity 方法。