POM

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-web</artifactId>
    <version>5.2.8.RELEASE</version>
</dependency>

使用RestTemplate

String url = "http://127.0.0.1/rest/api"; // 支持路径参数
RestTemplate restTemplate = new RestTemplate();

// HEAD操作
HttpHeaders headers = restTemplate.headForHeaders(url);
MediaType mediaType = headers.getContentType();

// GET/POST操作
ResponseEntity<String> stringEntity = restTemplate.getForEntity(url, String.class); // postForEntity/postForLocation
//ResponseEntity<String> stringEntity = restTemplate.exchange(url, HttpMethod.GET, null, String.class);
String response = stringEntity.getBody();
//String response = restTemplate.getForObject(url, String.class); // postForObject

// 设置HttpMessageConverter
restTemplate.getMessageConverters().add(new FastJsonHttpMessageConverter());
//restTemplate.setMessageConverters(List.of(new FastJsonHttpMessageConverter()));

ResponseEntity<User> userEntity = restTemplate.getForEntity(url, User.class);
User user = userEntity.getBody();
//User user = restTemplate.getForObject(url, User.class);

提交表单

HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);

MultiValueMap<String, String> body = new LinkedMultiValueMap<>();
body.add("key", "value");

HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(body, headers);
ResponseEntity<String> responseEntity = restTemplate.postForEntity(url, request, String.class);

上传文件

HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.MULTIPART_FORM_DATA);

MultiValueMap<String, Object> body = new LinkedMultiValueMap<>();
body.add("file", new FileSystemResource("/path/to/file"));
InputStream in = new FileInputStream("/path/to/file");
body.add("file", new InputStreamResource(in) {
    @Override
    public String getFilename() {
        return "filename";
    }

    @Override
    public long contentLength() throws IOException {
        return in.available();
    }
});

HttpEntity<MultiValueMap<String, Object>> request = new HttpEntity<>(body, headers);
String response = restTemplate.postForObject(url, request, String.class);

设置超时

SimpleClientHttpRequestFactory requestFactory = new SimpleClientHttpRequestFactory(); // 使用HttpURLConnection
requestFactory.setConnectTimeout(60000);
requestFactory.setReadTimeout(60000);

RestTemplate restTemplate = new RestTemplate(requestFactory); // 默认即使用SimpleClientHttpRequestFactory

设置拦截器

restTemplate.setInterceptors(List.of(new ClientHttpRequestInterceptor() {
    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
        System.out.println("before execute");
        return execution.execute(request, body);
    }
}));

Spring Boot

自动配置类为RestTemplateAutoConfiguration

配置RestTemplate

@Bean
public RestTemplate restTemplate(RestTemplateBuilder restTemplateBuilder) {
    return restTemplateBuilder.build(); // 默认自动检测并设置requestFactory
}

woshikid / blog

Spring RestTemplate学习笔记 #158

Spring Boot