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java - 使用 RestTemplate 对 REST API 调用中的对象列表有空响应

问题描述

所以我正在开发一个 REST 客户端，它使用 REST API 来使用 Spring RestTemplate 获取 JSON 对象。所以我得到一个 HTTP 200 OK 响应，但类对象内的列表（设备）为空。但是会获取其他字段。当我使用 Postman 执行相同的请求时，它运行良好。这可能是什么原因？

RestTemplate 代码片段：

 RestTemplate restTemplate = new RestTemplate();
HttpHeaders requestHeaders = new HttpHeaders();
requestHeaders.add("Content-Type", "application/json");
requestHeaders.add("Authorization", "Bearer " + apiToken);
HttpEntity entity = new HttpEntity(requestHeaders);
ResponseEntity<CloverMerchant> response = restTemplate.exchange(getMerchantDetailsUrl, HttpMethod.GET, entity, CloverMerchant.class);
return response.getBody();

CloverMerchant 模型类：

private String id;
private String name;
private String website;
private boolean isBillable;
private CloverBusinessEquipments equipment;

// other relevant getters and setters

CloverBusinessEquipments 模型类：

private List<CloverBusinessEquipment> elements;

    public CloverBusinessEquipments() {
}

@JsonGetter("elements")
public List<CloverBusinessEquipment> getElements() {
    return elements;
}

CloverBusinessEquipment 模型类：

private String merchantId;
private String serialNumber;
private String equipmentCode;
private String equipmentCodeDesc;
private String provisionedDeviceType;
private boolean boarded;
private boolean provisioned;

// relevant getters and setters

来自 REST API 的预期响应 JSON：

{
  "id": "5ZTFCGXQKVZNA",
  "name": "xxxx",
  "website": "https://xxxx.io",
  "isBillable": false,
  "equipment": {
  "elements": [
    {
        "merchantId": "5ZTFCGXQKVZNA",
        "boarded": false,
        "provisioned": true,
        "serialNumber": "C030UQ71040182",
        "equipmentCode": "105J",
        "equipmentCodeDesc": "Clover Mini",
        "provisionedDeviceType": "MAPLECUTTER"
    },
    {
        "merchantId": "5ZTFCGXQKVZNA",
        "boarded": false,
        "provisioned": true,
        "serialNumber": "C050UQ75150054",
        "equipmentCode": "1297",
        "equipmentCodeDesc": "Clover Station 2018",
        "provisionedDeviceType": "GOLDENOAK"
       }
    ]
  }
}

标签： javaspringresttemplatejsonschema2pojo

解决方案

您需要如下改造您的课程并检查

删除 getter 方法
CloverMerchant.java 

private String id;
private String name;
private String website;
@JsonProperty("isBillable")
private boolean isBillable;
private CloverBusinessEquipments equipment;

使用以下代码更新 CloverBusinessEquipments。
CloverBusinessEquipments.java

private List<CloverBusinessEquipment> elements;

创建新的 PoJo 类
CloverBusinessEquipment.java

private String merchantId;
private String serialNumber;
private String equipmentCode;
private String equipmentCodeDesc;
private String provisionedDeviceType;
private boolean boarded;
private boolean provisioned;

主.java

ObjectMapper mapper = new ObjectMapper();
mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
String str = "{\"id\":\"5ZTFCGXQKVZNA\",\"name\":\"xxxx\",\"website\":\"https://xxxx.io\",\"isBillable\":true,\"equipment\":{\"elements\":[{\"merchantId\":\"5ZTFCGXQKVZNA\",\"boarded\":false,\"provisioned\":true,\"serialNumber\":\"C030UQ71040182\",\"equipmentCode\":\"105J\",\"equipmentCodeDesc\":\"Clover Mini\",\"provisionedDeviceType\":\"MAPLECUTTER\"},{\"merchantId\":\"5ZTFCGXQKVZNA\",\"boarded\":false,\"provisioned\":true,\"serialNumber\":\"C050UQ75150054\",\"equipmentCode\":\"1297\",\"equipmentCodeDesc\":\"Clover Station 2018\",\"provisionedDeviceType\":\"GOLDENOAK\"}]}}";
CloverMerchant cv = mapper.readValue(str, CloverMerchant.class);
System.out.println(cv.getId()); //5ZTFCGXQKVZNA
System.out.println(cv.getEquipment().getElements().size()); //2

如果您可以检查 main 方法，我可以从问题中发布的 Json String 反序列化它。
我正在使用杰克逊 2.9.8

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