Spring Boot：使用 RestTemplate 调用查询

Question

我刚开始使用 Spring Boot，我想使用 RestTemplate 来调用查询和 return 它的结果。

@Repository
public interface ApplicantRepository extends CrudRepository<Applicant, Integer> {

@Query("SELECT a FROM Applicant a WHERE a.propertyTypeId = :typeId" +
        " AND a.bedrooms = :bedrooms" +
        " AND a.budget = :price")
List<Applicant> findByMatchingCriteria(@Param("typeId")int typeId, @Param("bedrooms") int bedrooms,
                                      @Param("price") int price);
}

我正在调用此 RestController 中的查询 "findByMatchingCriteria"：

@RestController
public class MatchingController {

private RestTemplate restTemplate = new RestTemplate();

@RequestMapping(method = GET, value = "matchingByProperty/{propertyId}")
public List matchingByProperty(@PathVariable int propertyId) {
    Property property = restTemplate.getForObject("http://localhost:8080/api/properties/" + propertyId, Property.class);

    return restTemplate.getForObject("http://localhost:8080/api/applicants/search/findByMatchingCriteria?typeId=" + property.getTypeId()
                                            + "&bedrooms=" + property.getBedrooms()
                                            + "&price=" + property.getPrice(), List.class);
}
}

属性看起来像这样：

@Entity
public class Property {
private @Id @GeneratedValue int id;
private String fullAddress;
private int typeId;
private int subtypeId;
private int bedrooms;
private int price;

private Property() {}

public Property(String fullAddress, int typeId, int subtypeId, int bedrooms, int price) {
    this.fullAddress = fullAddress;
    this.typeId = typeId;
    this.subtypeId = subtypeId;
    this.bedrooms = bedrooms;
    this.price = price;
}
// getters and setters
}

当我测试 "matchingByProperty/{propertyId}" url 时，出现以下错误：

exec-5] .w.s.m.s.DefaultHandlerExceptionResolver : Failed to read HTTP     message: org.springframework.http.converter.HttpMessageNotReadableException: Could not read document: Can not deserialize instance of java.util.ArrayList out of START_OBJECT token
 at [Source: java.io.PushbackInputStream@3bd79387; line: 1, column: 1]; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize instance of java.util.ArrayList out of START_OBJECT token
 at [Source: java.io.PushbackInputStream@3bd79387; line: 1, column: 1]

如何使用 RestTemplate 调用查询？或者有更好的方法吗？

Answer 1

如果您只想从控制器调用您自己的存储库，则无需使用 RestTemplate 通过 HTTP。只需将存储库注入您的控制器，然后调用方法：

@RestController
public class MatchingController {

  @Autowired
  private ApplicantRepository applicantRepository;

  @RequestMapping(method = GET, value = "matchingByProperty/{propertyId}")
  public List matchingByProperty(@PathVariable int propertyId) {
    // You probably should not be going over HTTP for this either
    // and autowiring a property repository.
    Property property = restTemplate.
      getForObject("http://localhost:8080/api/properties/" + propertyId, Property.class);

    return applicantRepository.findByMatchingCriteria(property.getTypeId(), property.getBedrooms(), property.getPrice());
  }
}

如果您出于某种原因确实想通过 HTTP，您可以使用此处找到的方法：Get list of JSON objects with Spring RestTemplate

Answer 2

想出了解决我的问题的方法。

在调用 ApplicantRepository 查询的 ApplicantController 中创建了一个 REST 方法：

@RequestMapping(method = POST, value = "/api/applicants/getMatchedApplicants")
public List getMatchedApplicants(@RequestBody HashMap property) {

    List<Applicant> applicants = applicantRepository.matchedApplicants((int) property.get("typeId"),
                                                                        (int) property.get("bedrooms"),
                                                                        (int) property.get("price"));

    return applicants == null ? new ArrayList() : applicants;
}

然后MatchingController通过REST调用ApplicantController中的方法

这就是我想要的，两个不同的服务（匹配和申请人）通过 REST 进行通信。

谢谢@Adam，你的建议对我很有帮助。

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