如何在Spring Rest Client中获取页面内容

Question

我有以下REST控制器：

@RestController
class PersonController {

   final PersonService personService

   @Autowired
   PersonController( PersonService personService ){
    this.personService = personService
   }

   @RequestMapping(value="/persons",method=RequestMethod.GET)
   Page<Person> list( Pageable pageable){
     Page<Person> persons = personService.listAllByPage(pageable)
     persons
   } 
}

以下存储库：

interface PersonRepository extends PagingAndSortingRepository<Person,Integer> {

}

以及服务：

interface PersonService {
   Page<Person> listAllByPage(Pageable pageable)
}

@Service
class PersonServiceImpl implements PersonService {

   final PersonRepository personRepository

   @Autowired
   PersonServiceImpl(PersonRepository personRepository){
      this.personRepository = personRepository
   }

   @Override
   Page<Person> listAllByPage(Pageable pageable) {
       personRepository.findAll(pageable)
   } 
}

服务器按预期工作，但客户端有问题。我不知道如何从回复中获取内容。

在客户端我有一个这样的方法：

@Override
public List<PersonDTO> findAll() throws DataAccessException {
    try {
        restClient.getServiceURI(PERSON_URL));
        ResponseEntity<PageImpl<PersonDTO>> response =
            restClient.exchange(
                restClient.getServiceURI(PERSON_URL),
                HttpMethod.GET,
                null,
                new ParameterizedTypeReference<PageImpl<PersonDTO>>() {
                });
        return response.getBody().getContent();
    } catch (Exception e){}
}

但是我有以下例外：

 org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class org.springframework.data.domain.PageImpl]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `org.springframework.data.domain.PageImpl` (no Creators, like default construct, exist): cannot deserialize from Object value (no delegate- or property-based Creator)

现在我阅读了这个stackoverflow条目并添加了CustomPageImpl类：如何使用页面

我将客户端中的方法更改为以下内容：

@Override
public List<PersonDTO> findAll() throws DataAccessException {
    try {
        restClient.getServiceURI(PERSON_URL));
        ResponseEntity<CustomPageImpl<PersonDTO>> response =
            restClient.exchange(
                restClient.getServiceURI(PERSON_URL),
                HttpMethod.GET,
                null,
                new ParameterizedTypeReference<CustomPageImpl<PersonDTO>>() {
                });
        return response.getBody().getContent();
    } catch (Exception e){}
}

但现在我得到了几乎相同的例外：

 org.springframework.http.converter.HttpMessageConversionException: Type definition error: [simple type, class org.springframework.data.domain.Pageable]; nested exception is com.fasterxml.jackson.databind.exc.InvalidDefinitionException: Cannot construct instance of `org.springframework.data.domain.Pageable` (no Creators, like default construct, exist): abstract types either need to be mapped to concrete types, have custom deserializer, or contain additional type information

Answer 1

在您提到的同一个堆栈溢出条目中，有一个针对exchange请求的解决方案。您可以使用PagedResources而不是页面/自定义实现。有关更多详细信息，请参阅此链接。

以下是您的要求：-

ResponseEntity<PagedResources<PersonDTO>> response =
            restClient.exchange(
                restClient.getServiceURI(PERSON_URL),
                HttpMethod.GET,
                null,
                new ParameterizedTypeReference<PagedResources<PersonDTO>>() {
                });
PagedResources<PersonDTO> resBody = response.getBody();
        return resBody.getContent();// Returns a collection