Spring HATEOAS 链接 return 单个对象的 HAL 格式，以及对象数组的规范格式

Question

我正在使用 Spring HATEOAS 0.20（也尝试过 0.23），当 return 使用单个对象与对象数组时，似乎有非常奇怪的行为。当 returning 单个对象时，生成的 JSON returns HATEOAS 链接通过 HAL 规范格式化（“_links”，我不想要）：

{
  "_Id": 161,
  ...
  "_links": {
    "self": {
      "href": "http://localhost:8080/library/161"
    }
  }
}

当 returning 对象数组时，生成的 JSON returns HATEOAS 链接采用规范格式（"links"，我确实想要）：

[
  {
    "_Id": 277,
    ...
    "links": [
      {
        "rel": "self",
        "href": "http://localhost:8080/library/277"
      }
    ]
  }
]

我没有指定@EnableHypermediaSupport，所以应该不支持HAL。但是，当 returning 单个对象时，我仍然得到 HAL 格式。

有谁知道为什么会这样？需要通过 HATEOAS 规范对 return 具有 HATEOAS 链接的单个对象执行哪些操作？

===== 根据更多信息的请求更新到 POST =====

如果我 return JSON 使用以下代码加载，我将获得 HAL 链接：

//
//------------------- Get Single Membership As Single Object ----------------------------------------------
//
@PreAuthorize("hasRole('ROLE_ADMIN')")
@RequestMapping(value = REQUEST_GET_MEMBERSHIP, method = RequestMethod.GET,  produces = { MediaType.APPLICATION_JSON_VALUE })
public ResponseEntity<MembershipResource> getMembership(@PathVariable("membership-id") Integer membershipId) {
    Membership membership = membershipRepository.findOne(membershipId);

    if (membership == null) {
        HttpHeaders headers = new HttpHeaders();
        headers.add("error", "Membership with ID of " + membershipId + " does not exist.");
        return new ResponseEntity<MembershipResource>(headers, HttpStatus.NOT_FOUND);
    }

    MembershipResourceAssembler assm = new MembershipResourceAssembler();
    MembershipResource membershipResource = assm.toResource(membership);

    System.out.println("membership id: " + membership.getId());
    return new ResponseEntity<MembershipResource>(membershipResource, HttpStatus.OK);
}

以上将生成 HAL 规范样式链接：

{
  "_Id": 277,
  "member": {
    "_Id": 112,
    "title": "Mr.",
    "firstName": "ABC",
    "middleName": "",
    "lastName": "XYZ",
    "active": true,
    "_links": {
      "self": {
        "href": "http://localhost:8080/members/112"
      }
    }
  },
  "membershipTermType": "2016",
  "card": {
    "_Id": 27,
    "name": "27",
    "graphicUrl": "",
    "number": 27,
  },
  "active": false,
  "paid": true,
  "renewal": true,
  "termsAndConditionsAcknowledged": true,
  "_links": {
    "self": {
      "href": "http://localhost:8080/memberships/277"
    }
  }
}

如果我将方法修改为 return 单个成员的列表，returned JSON 加载是带有 HATEOAS 规范的链接：

//
//------------------- Get Single Membership As List --------------------------------------------------------
//
@PreAuthorize("hasRole('ROLE_ADMIN')")
@RequestMapping(value = REQUEST_GET_MEMBERSHIP, method = RequestMethod.GET,  produces = { MediaType.APPLICATION_JSON_VALUE })
public ResponseEntity<List<MembershipResource>> getMembership(@PathVariable("membership-id") Integer membershipId) {
    Membership membership = membershipRepository.findOne(membershipId);

    if (membership == null) {
        HttpHeaders headers = new HttpHeaders();
        headers.add("error", "Membership with ID of " + membershipId + " does not exist.");
        return new ResponseEntity<List<MembershipResource>>(headers, HttpStatus.NOT_FOUND);
    }

    MembershipResourceAssembler assm = new MembershipResourceAssembler();
        MembershipResource membershipResource = assm.toResource(membership);

    ArrayList<MembershipResource> list = new ArrayList<MembershipResource>();
    list.add(membershipResource);

    System.out.println("membership id: " + membership.getId());
    return new ResponseEntity<List<MembershipResource>>(list, HttpStatus.OK);
}

以上将生成 HATEOAS 规范样式链接：

[
  {
    "_Id": 277,
    "member": {
      "_Id": 112,
      "title": "Mr.",
      "firstName": "ABC",
      "middleName": "",
      "lastName": "XYZ",
      "active": true,
      "links": [
        {
          "rel": "self",
          "href": "http://localhost:8080/members/112"
        }
      ]
    },
    "membershipTermType": "2016",
    "card": {
      "_Id": 27,
      "name": "27",
      "graphicUrl": "",
      "number": 27,
      "links": []
    },
    "active": false,
    "renewal": true,
    "paid": true,
    "termsAndConditionsAcknowledged": true,
    "links": [
      {
        "rel": "self",
        "href": "http://localhost:8080/memberships/277"
      }
    ]
  }
]

有谁知道为什么会这样？需要通过 HATEOAS 规范对 return 具有 HATEOAS 链接的单个对象执行哪些操作？

Answer 1

由于我使用 Spring Boot 作为我的应用程序服务器，@zeroflagL 建议我尝试在您的应用程序中添加 @EnableAutoConfiguration(exclude = HypermediaAutoConfiguration.class) 或在您的属性文件中添加 spring.hateoas.use-hal-as-default-json-media-type=false。

将 @EnableAutoConfiguration(exclude = HypermediaAutoConfiguration.class) 的配置注释添加到我的应用程序 class 解决了这个问题。

Spring HATEOAS 链接 return 单个对象的 HAL 格式，以及对象数组的规范格式

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