com.fasterxml.jackson.databind.exc.MismatchedInputException：无法从 START_ARRAY 令牌中反序列化 Object 的实例

Question

我陷入了 JSON 到 Java 对象之间的映射问题。 我正在使用 RestTemplate 在 Spring Boot 中进行第三方 API 调用。

{
"parsed": [
        {
            "food": {
                "foodId": "<FoodID>",
                "label": "apple",
                "nutrients": {
                    "ENERC_KCAL": 52,
                    "PROCNT": 0.26,
                    "FAT": 0.17,
                    "CHOCDF": 13.81,
                    "FIBTG": 2.4
                },
                "category": "Generic foods",
                "categoryLabel": "food",
                "image": "<Image URL>"
            }
        }
    ]
}

我在下面创建了相同的类（有 getter 和 setter）。

@Component
@Scope("prototype")
@JsonIgnoreProperties(ignoreUnknown = true)
public class ResponseFoodDetailsFromAPI implements Serializable{
    private static final long serialVersionUID = -1927057943962033354L;
    ParsesList parsed;
}

public class ParsesList implements Serializable{
    private static final long serialVersionUID = 5902036842725888370L;
    List<Parse> parse;
}

public class Parse implements Serializable{
    private static final long serialVersionUID = -8651880919902785186L;
    private Food food;  

}

public class Food implements Serializable{
    private static final long serialVersionUID = -5933882633489466961L;
    private String foodId;
    private String label;
    Nutrients NutrientsObject;
    private String brand;
    private String category;
    private String categoryLabel;
    private String foodContentsLabel;
    private String image;
}

public class Nutrients implements Serializable{
    private static final long serialVersionUID = -8207662942326982309L;
    private float ENERC_KCAL;
    private float PROCNT;
    private float FAT;
    private float CHOCDF;
    private float FIBTG;
}

但我遇到了异常

[Request processing failed; nested exception is org.springframework.web.client.RestClientException: Error while extracting 
response for type [class com.vikas.projects.organicecommerce.redisapicall.models.ResponseFoodDetailsFromAPI] 
and content type [application/json;charset=UTF-8]; 
nested exception is org.springframework.http.converter.HttpMessageNotReadableException: JSON parse error: 
Cannot deserialize instance of 
`com.vikas.projects.organicecommerce.redisapicall.models.ParsesList` 
out of START_ARRAY token; nested exception is com.fasterxml.jackson.databind.exc.MismatchedInputException: 
Cannot deserialize instance of `com.vikas.projects.organicecommerce.redisapicall.models.ParsesList` out of START_ARRAY 
token at [Source: (PushbackInputStream); line: 3, column: 14] (through reference chain:
 com.vikas.projects.organicecommerce.redisapicall.models.ResponseFoodDetailsFromAPI["parsed"])]
 with root cause

com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot deserialize instance of `com.vikas.projects.organicecommerce.redisapicall.models.ParsesList` out of START_ARRAY token
 at [Source: (PushbackInputStream); line: 3, column: 14] (through reference chain: com.vikas.projects.organicecommerce.redisapicall.models.ResponseFoodDetailsFromAPI["parsed"])
    at com.fasterxml.jackson.databind.exc.MismatchedInputException.from(MismatchedInputException.java:59) ~[jackson-databind-2.10.4.jar:2.10.4]
    at com.fasterxml.jackson.databind.DeserializationContext.reportInputMismatch(DeserializationContext.java:1445) ~[jackson-databind-2.10.4.jar:2.10.4]
    at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1219) ~[jackson-databind-2.10.4.jar:2.10.4]
    at com.fasterxml.jackson.databind.DeserializationContext.handleUnexpectedToken(DeserializationContext.java:1171) ~[jackson-databind-2.10.4.jar:2.10.4]
    at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromArray(BeanDeserializerBase.java:1478) 

添加的 JSON 是完整 JSON 的一部分。如果需要完整的 JSON，请告诉我。

Answer 1

根据您共享的 JSON，您需要更正几件事

@Component
@Scope("prototype")
@JsonIgnoreProperties(ignoreUnknown = true)
public class ResponseFoodDetailsFromAPI implements Serializable{
    private static final long serialVersionUID = -1927057943962033354L;
    List<Parse> parsed;
}

@JsonIgnoreProperties(ignoreUnknown = true)
public class Food implements Serializable{
    private static final long serialVersionUID = -5933882633489466961L;
    private String foodId;
    private String label;
    Nutrients nutrients;
    private String brand;
    private String category;
    private String categoryLabel;
    private String foodContentsLabel;
    private String image;
}