Spring RestTemplate用法

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Get请求

getForEntity 类方法返回的数据类型为 ResponseEntity<T> , 然后重载方法, 以不同的方式传递参数

  • getForEntity(String url, Class<T> responseType, Object... uriVariables)

  • getForEntity(String url, Class<T> responseType, Map<String, ?> uriVariables)

  • getForEntity(URI url, Class<T> responseType)

示例: 

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// 1
ResponseEntity<Yiyan> entity1 = restTemplate
    .getForEntity("https://v1.hitokoto.cn/?c={1}&encode={2}", Yiyan.class, "h", "json");

// 2
Map<String, String> map = new HashMap<>();
map.put("1", "i");
map.put("2", "json");
ResponseEntity<Yiyan> entity2 = restTemplate
    .getForEntity("https://v1.hitokoto.cn/?c={1}&encode={2}", Yiyan.class, map);

// 3
String url3 = "https://v1.hitokoto.cn/?c={1}&encode={2}";
URI uri3 = UriComponentsBuilder.fromUriString(url3).build("c", "json");
ResponseEntity<Yiyan> entity3 = restTemplate.getForEntity(uri3, Yiyan.class);

如果希望接口直接返回需要的数据类型, 则可以使用下面这组方法, 返回的数据类型就是传入的T

  • getForObject(String url, Class<T> responseType, Object... uriVariables)
  • getForObject(String url, Class<T> responseType, Map<String, ?> uriVariables)
  • getForObject(URI url, Class<T> responseType)

示例:

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// 1
Yiyan yiyan1 = restTemplate
    .getForObject("https://v1.hitokoto.cn/?c={1}&encode={2}", Yiyan.class, "h", "json");
System.out.println(yiyan1);

// 2
Map<String, String> map = new HashMap<>();
map.put("1", "i");
map.put("2", "json");
Yiyan yiyan2 = restTemplate.getForObject("https://v1.hitokoto.cn/?c={1}&encode={2}", Yiyan.class, map);
System.out.println(yiyan2);

// 3
String url3 = "https://v1.hitokoto.cn/?c={1}&encode={2}";
URI uri3 = UriComponentsBuilder.fromUriString(url3).build("c", "json");
Yiyan yiyan3 = restTemplate.getForObject(uri3, Yiyan.class);

Post

Post和Get方法一样, 有postForObject和postForEntity方法

  • postForObject(URI url, @Nullable Object request, Class<T> responseType)
  • postForObject(String url, @Nullable Object request, Class<T> responseType, Object... uriVariables)
  • postForObject(String url, @Nullable Object request, Class<T> responseType, Map<String, ?> uriVariables)

postForEntity类方法

  • postForEntity(URI url, @Nullable Object request, Class<T> responseType)
  • postForEntity(String url, @Nullable Object request, Class<T> responseType, Object... uriVariables)
  • postForEntity(String url, @Nullable Object request, Class<T> responseType, Map<String, ?> uriVariables)

除此之外, 还有postForLocation, 但是这类方法的返回值为URI, 没法接收响应体

exchange

这组方法偏底层, 比如需要设置请求头时使用

  • exchange(RequestEntity<?> requestEntity, Class<T> responseType)
  • exchange(URI url, HttpMethod method, @Nullable HttpEntity<?> requestEntity, Class<T> responseType)
  • exchange(String url, HttpMethod method, @Nullable HttpEntity<?> requestEntity, Class<T> responseType, Object... uriVariables)
  • exchange(String url, HttpMethod method, @Nullable HttpEntity<?> requestEntity, Class<T> responseType, Map<String, ?> uriVariables)

参数示例:

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// URI构造方式
// 1
URI uri = new URI("https://v1.hitokoto.cn/?c=h&encode=json");
// 2
URI uri = new UriTemplate("https://v1.hitokoto.cn/?c={1}&encode={2}").expand("h", "json");
// 或者 
Map<String, Object> map = new HashMap<>();
map.put("1", "h");
map.put("2", "json");
URI uri2 = new UriTemplate(url).expand(map);
// 3
URI uri = UriComponentsBuilder.fromUriString("https://v1.hitokoto.cn/?c={1}&encode={2}").build("h", "json");

// HttpEntity构造方式
HttpHeaders httpHeaders = new HttpHeaders();
HttpEntity<User> httpEntity = new HttpEntity<>(objBody, httpHeaders);
// RequestEntity继承了HttpEntity
RequestEntity<User> entity1 = RequestEntity.post(uri).header("Authorization", "Bearer xxxx").body(user);

请求示例:

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// 1
String url = "https://v1.hitokoto.cn/?c={1}&encode={2}";
URI uri = UriComponentsBuilder.fromUriString(url).build("h", "json");
RequestEntity<Void> request = RequestEntity.get(uri).accept(MediaType.APPLICATION_JSON)
    .header("Authorization", "123").build();
ResponseEntity<Yiyan> entity4 = restTemplate.exchange(request, Yiyan.class);

// 2
URI uri = new URI("https://gorest.co.in/public-api/users");

HttpHeaders httpHeaders = new HttpHeaders();
httpHeaders.add("Authorization", "Bearer XXXXXX");
httpHeaders.setContentType(MediaType.APPLICATION_JSON_UTF8);

User user = new User();
user.setFirst_name("Brian");
user.setLast_name("Ratke");
user.setGender("male");
user.setEmail("lew19@163.com");
user.setStatu("active");
HttpEntity<User> httpEntity = new HttpEntity<>(user, httpHeaders);

ResponseEntity<User> entity = restTemplate.exchange(uri, HttpMethod.POST, httpEntity, User.class);
System.out.println(entity);

// 3
ResponseEntity<Yiyan> entity2 = restTemplate.exchange("https://v1.hitokoto.cn/?c={1}&encode={2}", HttpMethod.GET, null, Yiyan.class, "h", "json");

// 4 略

下面这类方法是为了支持泛型, 比如, 返回数据类型是List, 但用上面方法无法进一步设置List内元素类型

  • exchange(RequestEntity<?> requestEntity, ParameterizedTypeReference<T> responseType)
  • exchange(URI url, HttpMethod method, @Nullable HttpEntity<?> requestEntity, ParameterizedTypeReference<T> responseType)
  • exchange(String url, HttpMethod method, @Nullable HttpEntity<?> requestEntity, ParameterizedTypeReference<T> responseType, Object... uriVariables)
  • exchange(String url, HttpMethod method, @Nullable HttpEntity<?> requestEntity, ParameterizedTypeReference<T> responseType, Map<String, ?> uriVariables)