我有两个问题:
如何使用Spring RestTemplate映射JSON对象列表。 如何映射嵌套的JSON对象。
我试图消费https://bitpay.com/api/rates，从http://spring.io/guides/gs/consuming-rest/遵循教程。
当前回答
实际上，我之前为我的一个项目开发了一些功能，以下是代码:
/**
* @param url is the URI address of the WebService
* @param parameterObject the object where all parameters are passed.
* @param returnType the return type you are expecting. Exemple : someClass.class
*/
public static <T> T getObject(String url, Object parameterObject, Class<T> returnType) {
try {
ResponseEntity<T> res;
ObjectMapper mapper = new ObjectMapper();
RestTemplate restTemplate = new RestTemplate();
restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
restTemplate.getMessageConverters().add(0, new StringHttpMessageConverter(Charset.forName("UTF-8")));
((SimpleClientHttpRequestFactory) restTemplate.getRequestFactory()).setConnectTimeout(2000);
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity<T> entity = new HttpEntity<T>((T) parameterObject, headers);
String json = mapper.writeValueAsString(restTemplate.exchange(url, org.springframework.http.HttpMethod.POST, entity, returnType).getBody());
return new Gson().fromJson(json, returnType);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* @param url is the URI address of the WebService
* @param parameterObject the object where all parameters are passed.
* @param returnType the type of the returned object. Must be an array. Exemple : someClass[].class
*/
public static <T> List<T> getListOfObjects(String url, Object parameterObject, Class<T[]> returnType) {
try {
ObjectMapper mapper = new ObjectMapper();
RestTemplate restTemplate = new RestTemplate();
restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
restTemplate.getMessageConverters().add(0, new StringHttpMessageConverter(Charset.forName("UTF-8")));
((SimpleClientHttpRequestFactory) restTemplate.getRequestFactory()).setConnectTimeout(2000);
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity<T> entity = new HttpEntity<T>((T) parameterObject, headers);
ResponseEntity<Object[]> results = restTemplate.exchange(url, org.springframework.http.HttpMethod.POST, entity, Object[].class);
String json = mapper.writeValueAsString(results.getBody());
T[] arr = new Gson().fromJson(json, returnType);
return Arrays.asList(arr);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
我希望这能帮助到别人!
其他回答
首先定义一个对象来保存返回数组的实体。如。
@JsonIgnoreProperties(ignoreUnknown = true)
public class Rate {
private String name;
private String code;
private Double rate;
// add getters and setters
}
然后你可以使用该服务并通过以下方式获得一个强类型列表:
ResponseEntity<List<Rate>> rateResponse =
restTemplate.exchange("https://bitpay.com/api/rates",
HttpMethod.GET, null, new ParameterizedTypeReference<List<Rate>>() {
});
List<Rate> rates = rateResponse.getBody();
上面的其他解决方案也可以工作，但我喜欢得到一个强类型列表，而不是Object[]。
我从这个帖子https://jira.spring.io/browse/SPR-8263找到了工作。
基于这篇文章，你可以返回一个类似这样的列表:
ResponseEntity<? extends ArrayList<User>> responseEntity = restTemplate.getForEntity(restEndPointUrl, (Class<? extends ArrayList<User>>)ArrayList.class, userId);
在我的情况下，我更喜欢提取一个字符串，然后使用JsonNode接口浏览上下文
var response = restTemplate.exchange("https://my-url", HttpMethod.GET, entity, String.class);
if (response.getStatusCode() == HttpStatus.OK) {
var jsonString = response.getBody();
ObjectMapper mapper = new ObjectMapper();
JsonNode actualObj = mapper.readTree(jsonString);
System.out.println(actualObj);
}
或者很快
ObjectNode actualObj= restTemplate.getForObject("https://my-url", ObjectNode.class);
然后读取内部数据与路径表达式，即。
boolean b = actualObj.at("/0/states/0/no_data").asBoolean();
经过多次测试，这是我发现的最好的方法:)
Set<User> test = httpService.get(url).toResponseSet(User[].class);
这就是你所需要的
public <T> Set<T> toResponseSet(Class<T[]> setType) {
HttpEntity<?> body = new HttpEntity<>(objectBody, headers);
ResponseEntity<T[]> response = template.exchange(url, method, body, setType);
return Sets.newHashSet(response.getBody());
}
实际上，我之前为我的一个项目开发了一些功能，以下是代码:
/**
* @param url is the URI address of the WebService
* @param parameterObject the object where all parameters are passed.
* @param returnType the return type you are expecting. Exemple : someClass.class
*/
public static <T> T getObject(String url, Object parameterObject, Class<T> returnType) {
try {
ResponseEntity<T> res;
ObjectMapper mapper = new ObjectMapper();
RestTemplate restTemplate = new RestTemplate();
restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
restTemplate.getMessageConverters().add(0, new StringHttpMessageConverter(Charset.forName("UTF-8")));
((SimpleClientHttpRequestFactory) restTemplate.getRequestFactory()).setConnectTimeout(2000);
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity<T> entity = new HttpEntity<T>((T) parameterObject, headers);
String json = mapper.writeValueAsString(restTemplate.exchange(url, org.springframework.http.HttpMethod.POST, entity, returnType).getBody());
return new Gson().fromJson(json, returnType);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
/**
* @param url is the URI address of the WebService
* @param parameterObject the object where all parameters are passed.
* @param returnType the type of the returned object. Must be an array. Exemple : someClass[].class
*/
public static <T> List<T> getListOfObjects(String url, Object parameterObject, Class<T[]> returnType) {
try {
ObjectMapper mapper = new ObjectMapper();
RestTemplate restTemplate = new RestTemplate();
restTemplate.getMessageConverters().add(new MappingJackson2HttpMessageConverter());
restTemplate.getMessageConverters().add(0, new StringHttpMessageConverter(Charset.forName("UTF-8")));
((SimpleClientHttpRequestFactory) restTemplate.getRequestFactory()).setConnectTimeout(2000);
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);
HttpEntity<T> entity = new HttpEntity<T>((T) parameterObject, headers);
ResponseEntity<Object[]> results = restTemplate.exchange(url, org.springframework.http.HttpMethod.POST, entity, Object[].class);
String json = mapper.writeValueAsString(results.getBody());
T[] arr = new Gson().fromJson(json, returnType);
return Arrays.asList(arr);
} catch (Exception e) {
e.printStackTrace();
return null;
}
}
我希望这能帮助到别人!
