java - Spring 启动: call a query using RestTemplate

Question

我刚开始使用 Spring Boot，我想使用 RestTemplate 来调用查询并返回其结果。

@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);
}

我在这个 RestController 中调用查询“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}”网址时，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 Controller 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(inject)您的 Controller ，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());
  }
}

如果出于某种原因你确实想通过 HTTP，你可以使用这里的方法:Get list of JSON objects with Spring RestTemplate