Java 使用spring hateoas使用基于HAL的REST服务

我正在尝试使用RestTemplate类使用基于HAL的REST服务。 响应主体如下所示：

{
  "_embedded": {
    "school:teachers": [
      {
        "name": "Adams",
        "state": "CA",
        "_links": {
          "self": {
            "href": "http://localhost:8080/api/teachers/1"
          }
        }
      },
      {
        "name": "Barnes",
        "state": "FL",
        "_links": {
          "self": {
            "href": "http://localhost:8080/api/teachers/2"
          }
        }
      },
      {
        "name": "Armstrong",
        "state": "GA",
        "_links": {
          "self": {
            "href": "http://localhost:8080/api/teachers/3"
          }
        }
      }
    ]
  },
  "_links": {
    "curies": [
      {
        "href": "http://localhost:8080/docs/html5/{rel}.html",
        "name": "school",
        "templated": true
      }
    ]
  }
}

public class Teacher {
    private String name;
    private String state;

    // getters and setters...
}

...
RestTemplate restTemplate = new RestTemplate();

Map<String, Object> dummy = new HashMap<>();
HttpEntity<String> httpEntity = getHttpEntity(); 

ResponseEntity<Resources<Resource<Teacher>>> response = restTemplate.exchange(url,
                HttpMethod.GET,
                httpEntity,
                new ParameterizedTypeReference<Resources<Resource<Teacher>>>() {});

Resources<Resource<Teacher>> resources = response.getBody();
...

教师

课程如下所示：

{
  "_embedded": {
    "school:teachers": [
      {
        "name": "Adams",
        "state": "CA",
        "_links": {
          "self": {
            "href": "http://localhost:8080/api/teachers/1"
          }
        }
      },
      {
        "name": "Barnes",
        "state": "FL",
        "_links": {
          "self": {
            "href": "http://localhost:8080/api/teachers/2"
          }
        }
      },
      {
        "name": "Armstrong",
        "state": "GA",
        "_links": {
          "self": {
            "href": "http://localhost:8080/api/teachers/3"
          }
        }
      }
    ]
  },
  "_links": {
    "curies": [
      {
        "href": "http://localhost:8080/docs/html5/{rel}.html",
        "name": "school",
        "templated": true
      }
    ]
  }
}

public class Teacher {
    private String name;
    private String state;

    // getters and setters...
}

...
RestTemplate restTemplate = new RestTemplate();

Map<String, Object> dummy = new HashMap<>();
HttpEntity<String> httpEntity = getHttpEntity(); 

ResponseEntity<Resources<Resource<Teacher>>> response = restTemplate.exchange(url,
                HttpMethod.GET,
                httpEntity,
                new ParameterizedTypeReference<Resources<Resource<Teacher>>>() {});

Resources<Resource<Teacher>> resources = response.getBody();
...

GET方法的REST服务的返回类型为

ResponseEntity

。因此，我在客户端代码中的请求如下所示：

{
  "_embedded": {
    "school:teachers": [
      {
        "name": "Adams",
        "state": "CA",
        "_links": {
          "self": {
            "href": "http://localhost:8080/api/teachers/1"
          }
        }
      },
      {
        "name": "Barnes",
        "state": "FL",
        "_links": {
          "self": {
            "href": "http://localhost:8080/api/teachers/2"
          }
        }
      },
      {
        "name": "Armstrong",
        "state": "GA",
        "_links": {
          "self": {
            "href": "http://localhost:8080/api/teachers/3"
          }
        }
      }
    ]
  },
  "_links": {
    "curies": [
      {
        "href": "http://localhost:8080/docs/html5/{rel}.html",
        "name": "school",
        "templated": true
      }
    ]
  }
}

public class Teacher {
    private String name;
    private String state;

    // getters and setters...
}

...
RestTemplate restTemplate = new RestTemplate();

Map<String, Object> dummy = new HashMap<>();
HttpEntity<String> httpEntity = getHttpEntity(); 

ResponseEntity<Resources<Resource<Teacher>>> response = restTemplate.exchange(url,
                HttpMethod.GET,
                httpEntity,
                new ParameterizedTypeReference<Resources<Resource<Teacher>>>() {});

Resources<Resource<Teacher>> resources = response.getBody();
...

。。。
RestTemplate RestTemplate=新RestTemplate（）；
Map dummy=newhashmap（）；
HttpEntity HttpEntity=getHttpEntity（）；
ResponseEntity response=restemplate.exchange（url，
HttpMethod.GET，
httpEntity，
新的ParameteredTypeReference（）{}）；
Resources=response.getBody（）；
...

当我使用响应类型

ParameterizedTypeReference

发出请求时，响应的内容为空。当我使用

String

时，我检索内容列表

---

我应该如何使用响应类型

ParameterizedTypeReference

来请求检索它以直接在POJO中映射它？

当然，您应该使用Traverson

Traverson client = new Traverson(new URI("http://localhost:8080/api/"), 
         MediaTypes.HAL_JSON);
    Resources<Resource<Teacher>> teachers = client
        .follow("school:teachers")
        .toObject(new ResourcesType<Resource<Teacher>>(){});

Traverson客户端=新的Traverson（新的URI（“http://localhost:8080/api/"), 
MediaTypes.HAL_JSON）；
资源教师=客户
.follow（“学校：教师”）
.toObject（新的ResourcesType（）{}）；

---

我也面临类似的问题。我选择的解决方法是：

        ResponseEntity<String> response = restTemplate.exchange(
                "http://localhost:8080/payment/search/findByApprovalDate?approvalDate=2017-11-06", HttpMethod.GET,
                null, String.class);

        String data = response.getBody();

        ObjectMapper om = new ObjectMapper();
        om.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

        JsonNode jsNode = om.readTree(data);
        String test = jsNode.at("/_embedded/payment").toString();

        payments = om.readValue(test, new TypeReference<List<RHPayment>>() {
        });

ResponseEntity response=restemplate.exchange(
"http://localhost:8080/payment/search/findByApprovalDate?approvalDate=2017-11-06“，HttpMethod.GET，
null，String.class）；
字符串数据=response.getBody（）；
ObjectMapper om=新的ObjectMapper（）；
configure（在未知属性上反序列化feature.FAIL，false）；
JsonNode jsNode=om.readTree（数据）；
String test=jsNode.at（“/_embedded/payment”）.toString（）；
payments=om.readValue（测试，新类型引用（）{
});

我使用JAVA使用JSON+HAL资源。与中所示的RestTemplate相比，该库大大简化了资源消耗。

我尝试了与Vishnoo Rath类似的方法。我计划为我所有的资源建立一个通用的方法

ResponseEntity<String> response = 
                restTemplate.exchange("http://localhost:8081/rest/cars", HttpMethod.GET, null, String.class);

        String data = response.getBody();
        //log.info(data);

        ObjectMapper om = new ObjectMapper();
        om.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);

        JsonNode jsNode = om.readTree(data);
        String test = jsNode.at("/_embedded/cars").toString();
        //log.info(test);

        ArrayList<Car> cars = om.readValue(test, new TypeReference<List<Car>>() {
        });

        for (Car theCar : cars) {
            log.info(">>> " + theCar.getMake() + " " + theCar.getModel() + " " + theCar.getYear());
        }

ResponseEntity响应=
restTemplate.exchange（“http://localhost:8081/rest/cars，HttpMethod.GET，null，String.class）；
字符串数据=response.getBody（）；
//日志信息（数据）；
ObjectMapper om=新的ObjectMapper（）；
configure（在未知属性上反序列化feature.FAIL，false）；
JsonNode jsNode=om.readTree（数据）；
String test=jsNode.at（“/_embedded/cars”）.toString（）；
//日志信息（测试）；
ArrayList cars=om.readValue（测试，新类型引用（）{
});
汽车（汽车：汽车）{
log.info（“>>>>”+theCar.getMake（）+“”+theCar.getModel（）+“”+theCar.getYear（））；
}

您的服务返回

资源

似乎非常可疑。如果你控制代码，考虑改变它。也就是说，您必须在客户端使用

restemplate

？如果不是，则是更好的选择，因为它是为导航HAL响应而构建的，而

RestTemplate

不是。@AbhijitSarkar我不控制服务器端代码，因此我必须使用它。我从未听说过Traverson，我必须看看如何发出请求。@AbhijitSarkar

资源有什么问题？@AbhijitSarkar必须问同样的问题-该响应类型有什么问题？这既合法又普遍。特别是你为什么认为这很重要。当然，问题在于使用JSON？因此，服务器上的响应“type”不重要。请在回答中添加相关代码和说明，而不是链接到外部URL。