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

这里提到了3种检索对象列表的方法。所有这些都将完美地工作

@RequestMapping(value = "/emp2", produces = "application/json")
public List<Employee> getEmp2()
{
    HttpHeaders headers = new HttpHeaders();
    headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON));
    HttpEntity<String> entity = new HttpEntity<String>(headers);
    ResponseEntity<List<Employee>> response = restTemplate.exchange(
            "http://hello-server/rest/employees", HttpMethod.GET,entity, 
    new ParameterizedTypeReference<List<Employee>>() {});
    return response.getBody();
}

(或)

@RequestMapping(value = "/emp3", produces = "application/json")
public List<Employee> getEmp3()
{
    Employee[] empArray = restTemplate.getForObject("http://hello-server/rest/employees", Employee[].class);
    List<Employee> emp= Arrays.asList(empArray);
    return emp;
}

(或)

    @RequestMapping(value = "/emp4", produces = "application/json")
public Employee[] getEmp4()
{
    ResponseEntity<Employee[]> responseEntity = restTemplate.getForEntity("http://hello-server/rest/employees", Employee[].class);
    Employee[] empList = responseEntity.getBody();
    //MediaType contentType = responseEntity.getHeaders().getContentType();
    //HttpStatus statusCode = responseEntity.getStatusCode();
    return  empList;
}

Employee.class

public class Employee {

private Integer id;
private String name;
private String Designation;
private String company;

//getter setters and toString()

}

其他回答

考虑一下这个答案,特别是如果你想在列表中使用泛型 Spring RestTemplate和泛型类型ParameterizedTypeReference集合,如List<T>

也许这样……

ResponseEntity<Object[]> responseEntity = restTemplate.getForEntity(urlGETList, Object[].class);
Object[] objects = responseEntity.getBody();
MediaType contentType = responseEntity.getHeaders().getContentType();
HttpStatus statusCode = responseEntity.getStatusCode();

RequestMapping的控制器代码

@RequestMapping(value="/Object/getList/", method=RequestMethod.GET)
public @ResponseBody List<Object> findAllObjects() {

    List<Object> objects = new ArrayList<Object>();
    return objects;
}

ResponseEntity是HttpEntity的扩展,它添加了HttpStatus状态码。在RestTemplate和@Controller方法中使用。 在RestTemplate中,该类由getForEntity()和exchange()返回。

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!

更简单的方法: 我会给你们看Authorization heard和unauthorization header:

未经授权: a.进行依赖注入(构造函数注入): 你也可以选择字段注入。我考虑了构造函数注入。

public class RestTemplateService {
private final RestTemplate template;
public RestTemplateService(RestTemplate template) {
    this.template = template;
  }
}

b.调用getList()方法:

public ResponseEntity<List> getResponseList(String url, HttpMethod type) {
    return template.exchange(url, type, new HttpEntity<>(new HttpHeaders()), List.class);
  }

授权:我喜欢小方法。所以我把这些功能分开:

 public ResponseEntity<List> getResponse(String url, HttpMethod type) {
    return template.exchange(url, type, getRequest(getHeaders(USERNAME, PASS)), List.class);
  }

 private HttpEntity<String> getRequest(HttpHeaders headers) {
    return new HttpEntity<>(headers);
  }

 private HttpHeaders getHeaders(String username, String password) {
    HttpHeaders headers = new HttpHeaders();
    headers.add("Authorization", "Basic " + new String(Base64.encodeBase64((username + ":" + password).getBytes())));
    return headers;
  }

希望问题能得到解决!

你可以为每个条目创建POJO,

class BitPay{
private String code;
private String name;
private double rate;
}

然后使用BitPay列表的ParameterizedTypeReference,你可以使用:

RestTemplate restTemplate = new RestTemplate();
ResponseEntity<List<Employee>> response = restTemplate.exchange(
  "https://bitpay.com/api/rates",
  HttpMethod.GET,
  null,
  new ParameterizedTypeReference<List<BitPay>>(){});
List<Employee> employees = response.getBody();