无法从 STATT_OBJECT 令牌中反序列化 java.util.ArrayList 的实例

Question

我正在尝试使用 Jackson 将 JSON 反序列化为对象，但错误提示

“处理服务器错误：无法从 START_OBJECT 令牌中反序列化 java.util.ArrayList 的实例”

JSON 具有这种结构

[{
        "id": 685509210310,
        "intention_id": 13042,
        "cuit": "133423122",
        "branch": "Local",
        "checkout": "7",
        "establishment_id": "21312",
        "transaction_datetime": "2021-03-10T17:07:10",
        "payment_method_id": 1,
        "payment_method_code": "VI",
        "payment_method_type": "credit_card",
        "card_data": {
            "card_brand": "Visa",
            "bin": "1211111",
            "last_four_digits": "0000",
            "bank_data": {
                "id": 1,
                "description": "Banco"
            }
        },
        "amount": 1200.00,
        "currency": "ARS",
        "installments": 1,
        "status": "approved",
        "status_details": {
            "card_authorization_code": "11111",
            "card_reference_number": " 00000",
            "response": {
                "type": "approved",
                "reason": {
                    "id": 0,
                    "description": "APROBADA (authno)",
                    "ticket_footer": "INFO ADICIONAL "
                }
            }
        },
        "terminal_data": {
            "trace_number": 43,
            "ticket_number": 121,
            "terminal_number": "87212121"
        }
    }
]

我正在尝试将其反序列化到我的对象中，该对象具有内部 JSON 的其他类的列表，但它不起作用

转换方法是

Collection read = new ObjectMapper().readValue(new_salida, new TypeReference<Collection>() {});

Answer 1

您可以将TypeReference 用于List<YourObject> 并将其提供给ObjectMapper。

这是我的做法：

class SampleCardData {
    @JsonProperty
    private Long id;
    @JsonProperty("intention_id")
    private Long intention_id;

   ...ignored other properties...

    @Override
    public String toString() {
        return "SampleCardData{" +
                "id=" + id +
                ", intention_id=" + intention_id +
                '}';
    }
}

public class SampleParseSF {
    public static void main(String[] args) throws IOException {
        ObjectMapper objectMapper = new ObjectMapper()
                .configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        TypeReference<List<SampleCardData>> arrayTypeRef = new TypeReference<List<SampleCardData>>() {
        };
        File file = new File("type-ref.json");
        List<SampleCardData> sampleCardDataList = objectMapper.readValue(file, arrayTypeRef);
        System.out.println(sampleCardDataList);
    }
}

Answer 2

我通过这一行找到了答案

mapper.configure(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true);

Answer 3

我认为它不会像你尝试的那样工作

这是正确的方法

Collection<YourObject> read = new ObjectMapper().readValue(new_salida, YourObject[].class);

并且必须定义YourObject，以便它可以保存您期望的json值

>  {
>       "id":685509210310,
>       "intention_id":13042,
>       "cuit":"133423122",
>       "branch":"Local",
>       "checkout":"7",
>       "establishment_id":"21312",
>       "transaction_datetime":"2021-03-10T17:07:10",
>       "payment_method_id":1,
>       "payment_method_code":"VI",
>       "payment_method_type":"credit_card",
>       "card_data":{
>          "card_brand":"Visa",
>          "bin":"1211111",
>          "last_four_digits":"0000",
>          "bank_data":{
>             "id":1,
>             "description":"Banco"
>          }
>       },
>       "amount":1200.00,
>       "currency":"ARS",
>       "installments":1,
>       "status":"approved",
>       "status_details":{
>          "card_authorization_code":"11111",
>          "card_reference_number":" 00000",
>          "response":{
>             "type":"approved",
>             "reason":{
>                "id":0,
>                "description":"APROBADA (authno)",
>                "ticket_footer":"INFO ADICIONAL "
>             }
>          }
>       },
>       "terminal_data":{
>          "trace_number":43,
>          "ticket_number":121,
>          "terminal_number":"87212121"
>       }    }