反序列化嵌套的 Json 数组

Question

我有一些 Json 看起来像：{  "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“菜肴”。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;}我找到了这种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，如果我运行它，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为 POJO 而不是List<Details>

public class Dish {

@JsonProperty("name")

private String name;

@JsonProperty("details")

private Detail details;

}

Answer 2

你可以试试这个：

JavaType javaType = mapper.getTypeFactory().constructParametricType(List.class, Dish.class);
List<Dish> dishes = mapper.readValue("jsonString", javaType);