JsonArray 和 Gson

Question

我使用的 JSON 库是 Gson。我很难制定一个有效的数据类型来表示以下 JSON 字符串：

{  
   "latestoffers": [
      {
         "id": "4qXleunwNMCKi8M0q0CuMa",
         "price": "534.99",
         "firstrecorded_at": 1377808800,
         "lastrecorded_at": 1382862800,
         "seller": "Newegg",
         "availability": "In stock. [BBX: Buy Box]",
         "currency": "USD"
      },
      {
         "id": "4xTIQAPySG68IS0CGyOuyO",
         "price": "582.41",
         "firstrecorded_at": 1380725000,
         "lastrecorded_at": 1382862800,
         "seller": "Beach Audio",
         "currency": "USD"
      },
      {
         "id": "5nW67R2V4CwmE8cwaWsawe",
         "price": "578.04",
         "firstrecorded_at": 1379524200,
         "lastrecorded_at": 1379998900,
         "seller": "Beach Audio",
         "currency": "USD"
      }
      ],
   "offers_count": 6,
   "name": "newegg.com",
   "recentoffers_count": 2,
   "sku": "N82E16834216463",
   "url": "http://www.newegg.com/Product/Product.aspx?Item=N82E16834216463"
}

我的数据类（到目前为止）如下，我不知道如何完成的方法getOfferData()。我也不确定 JsonArray 是否是要使用的合适的 JSON 元素？

static class LatestOffers {

    Integer offers_count;
    String name;
    Integer recentoffers_count;
    String sku;
    String url;

    java.util.List<JsonArray> getOfferData() {

        List<JsonArray> list = new ArrayList<JsonArray>();
        // how do I get parse the 'id', 'price', 'firstrecorded_at' etc. to add them to the ArrayList?
          return list;
    }

    Integer getOffers_count() {
        return offers_count;
    }

    String getName() {
        return name;
    }

    Integer getRecentoffers_count() {
        return recentoffers_count;
    }

    String getSku() {
        return sku;
    }

    String getUrl() {
        return url;
    }
}

有什么帮助吗？谢谢。

编辑

事实证明我不必要地使事情复杂化，这按预期工作：

static class LatestOffers {
        List<Offer> latestoffers;

        List<Offer> getOffer() {
            return latestoffers;
        }
    }

    static class Offer {

        private String id;
        private String price;
        private long firstrecorded_at;
        private long lastrecorded_at;
        private String seller;
        private String availability;
        private String currency;

        String getId() {
            return id;
        }

        String getPrice() {
            return price;
        }

        long getFirstrecorded_at() {
            return firstrecorded_at;
        }

        long getLastrecorded_at() {
            return lastrecorded_at;
        }

        String getSeller() {
            return seller;
        }

        String getAvailability() {
            return availability;
        }

        String getCurrency() {
            return currency;
        }

    }

感谢所有回答的人，我接受 user2762451 的回答，因为他是第一个建议使用另一个类作为 Offer 数据的人。

Answer 1

我建议你为数组中的对象创建新的 POJO。

class Offer {
    private String id;
    private String price;
    private long firstRecordedAt;
    private long lastRecordedAt;
    private String seller;
    private String availability;
    private String currency;

}

您的LatestOffers 类可以有一个List<Offer> offers;，而getOfferData() 方法应该返回List<Offer>。

基本上如下：

static class LatestOfferDetail {
    private int offersCount;
    private String name;
    private int recentOffersCount;
    private String sku;
    private String url;
    private List<Offer> latestOffers = new ArrayList<Offer>();

    //other getters and setters
    public List<Offer> getLatestOffers() {
        return latestOffers;
    }
}

此外，您似乎在同一段代码和 JSON 中遵循多个命名约定。对于 JAVA，建议遵循 CamelCaseNaming。我已经更新了答案以反映这些。

另外，latestOffers 的 getter 方法的名称与约定不同。建议将其命名为 get{FieldName}。我已经更新了答案以反映这一点。

Answer 2

创建另一个 POJO，包含数组中使用的所有参数，如下所示：

public class MyOffer  
{  
  private String id;  
  private double price;  
  private long firstrecorded_at;  
  private long lastrecorded_at;  
  private String seller;  
  private String availability;  
  private String currency;  

  //your getter and setter methods here.
}   

在您的班级中包含上述 pojo 的列表LatestOffers：

List<MyOffer> latestoffers = new ArrayList<MyOffer>();    

你的班级LatestOffers 看起来像这样

static class LatestOffers   
{
    Integer offers_count;
    String name;
    Integer recentoffers_count;
    String sku;
    String url;

    List<MyOffer> latestoffers = new ArrayList<MyOffer>();

    //getter and setter method
}

测试主类：

public static void main(String[] args) {
    LatestOffers lso = new LatestOffers();
    lso.setName("N82E16834216463");
    lso.setOffers_count(6);
    lso.setRecentoffers_count(2);
    lso.setSku("N82E16834216463");
    lso.setUrl("http://www.newegg.com/Product/Product.aspx?Item=N82E16834216463");
    MyOffer offer = null;
    List<MyOffer> list = new ArrayList<MyOffer>();
    for(int i=0;i<2;i++){
        offer = new MyOffer();
        offer.setAvailability("In stock. [BBX: Buy Box]");
        offer.setCurrency("USD");
        offer.setFirstrecorded_at(1377808800);
        offer.setId("4qXleunwNMCKi8M0q0CuMa");
        offer.setLastrecorded_at(1382862800);
        offer.setPrice(534.99);
        offer.setSeller("Newegg");

        list.add(offer);
    }
    lso.setLatestoffers(list);
    Gson gson = new Gson();
    String json = gson.toJson(lso);
    System.out.println(json);

}

输出：

{
  "offers_count": 6,
  "name": "N82E16834216463",
  "recentoffers_count": 2,
  "sku": "N82E16834216463",
  "url": "http://www.newegg.com/Product/Product.aspx?Item=N82E16834216463",
  "latestoffers": [
    {
        "id": "4qXleunwNMCKi8M0q0CuMa",
        "price": 534.99,
        "firstrecorded_at": 1377808800,
        "lastrecorded_at": 1382862800,
        "seller": "Newegg",
        "availability": "In stock. [BBX: Buy Box]",
        "currency": "USD"
    },
    {
        "id": "4qXleunwNMCKi8M0q0CuMa",
        "price": 534.99,
        "firstrecorded_at": 1377808800,
        "lastrecorded_at": 1382862800,
        "seller": "Newegg",
        "availability": "In stock. [BBX: Buy Box]",
        "currency": "USD"
    }
  ]
}

无需定义getOfferData() 方法只需创建MyOffer 类的列表并将该列表设置为latestoffers 列表定义在您的类LatestOffers 中。当您将 POJO 转换为 JSON 字符串时，它会将您的列表序列化为 JsonArray。