java - 反序列化嵌套 Json 数组

Question

我有一些 Json，如下所示:

{
  "foo": [
    {
      "bar": "baz"
    }
  ],
  "foo2": [
    {
      "bar": "baz"
    }
  ],
  "dishes": [
    {
      "name": "tonno",
      "details": {
        "toppings": [
          "cheese",
          "tomato",
          "tuna"
        ],
        "price": 10
      }
    },
    {
      "name": "cheese",
      "details": {
        "toppings": [
          "cheese",
          "tomato"
        ],
        "price": 5
      }
    },
    {
      "name": "mexicana",
      "details": {
        "toppings": [
          "cheese",
          "tomato",
          "chicken"
        ],
        "price": 12,
        "inOffer": true
      }
    }
  ]
}

我对“foo”和“foo2”不感兴趣，只想反序列化“dishes”。为此我创建了两个类:

public class Dish {

    @JsonProperty("name")
    private String name;

    @JsonProperty("details")
    private List<Detail> details;
}

和

public class Detail {

    @JsonProperty("toppings")
    private List<String> toppings;

    @JsonProperty("price")
    private int price;

    @JsonProperty("inOffer")
    private boolean inOffer;
}

我找到了this方法并尝试了以下方法:

ObjectMapper mapper = new ObjectMapper();
mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
final JsonNode response = mapper.readTree(json).path("dishes");
final CollectionType collectionType = TypeFactory.defaultInstance().constructCollectionType(List.class, Dish.class);
List<Dish> dishes = mapper.readerFor(collectionType).readValue(response);

但是，如果我运行这个，我会得到

m.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `java.util.ArrayList` out of START_OBJECT token  at [Source: UNKNOWN; line: -1, column: -1]

如何使用嵌套数组反序列化嵌套 Json，而不必映射我不感兴趣的字段？

Answer 1

您应该映射details作为 POJO 而不是 List<Details>

public class Dish {

@JsonProperty("name")
private String name;

@JsonProperty("details")
private Detail details;

}