com.fasterxml.jackson.databind.JsonMappingException：无法反序列化 START_ARRAY 令牌

Question

我收到以下型号的 START_ARRAY 错误。我期待 InputDetails

的对象

class InputDetails{
  public List<EachFieldDetails> fieldDetails;
}

class EachFieldDetails{
  public String fieldName;
  public String value;
}

JSON输入如下：

[{"fieldName":"siteName","value":"Warehouse"},{"fieldName":"poNumber","value":"po1"},{"fieldName":"itemCode","value":"itemcode1"},{"fieldName":"asdnSerialNo","value":"null"}]

谁能给我解决方案。

这是我的class

public Response setWHDetails(@BeanParam RequestBean requestBean,InputDetails saveInputs)
{ 
  //Do operation   
}

Answer 1

您的 JSON 在您尝试反序列化为对象时指定了一个数组。

如果您的 JSON 是这样的：

{
    "fieldDetails" : [
        {"fieldName":"siteName","value":"Warehouse"},
        {"fieldName":"poNumber","value":"po1"},
        {"fieldName":"itemCode","value":"itemcode1"},
        {"fieldName":"asdnSerialNo","value":"null"}
    ]
}

它可能有效。或者，您可以直接反序列化为数组。

我说可能因为您没有提供任何代码或信息来说明您正在使用什么工具或库来处理反序列化过程。

Answer 2

您可能需要这个：

import java.io.File;
import java.io.IOException;
import java.util.List;

import org.codehaus.jackson.map.ObjectMapper;
import org.codehaus.jackson.type.TypeReference;

public class JacksonRead {
    public static void main(String[] args) {

        ObjectMapper mapper = new ObjectMapper();
        try {
            TypeReference<List<EachFieldDetails>> typeRef = new TypeReference<List<EachFieldDetails>>() {
            };
            List<EachFieldDetails> user = mapper.readValue(new File(
                    "d:\user.json"), typeRef);
            System.out.println(user);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

user.json

[{"fieldName":"siteName","value":"Warehouse"},{"fieldName":"poNumber","value":"po1"},{"fieldName":"itemCode","value":"itemcode1"},{"fieldName":"asdnSerialNo","value":"null"}]

EachFieldDetails.java

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;

@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({ "fieldName", "value" })
public class EachFieldDetails {

    @JsonProperty("fieldName")
    private String fieldName;
    @JsonProperty("value")
    private String value;

    /**
     * 
     * @return The fieldName
     */
    public String getFieldName() {
        return fieldName;
    }

    /**
     * 
     * @param fieldName
     *            The fieldName
     */
    public void setFieldName(String fieldName) {
        this.fieldName = fieldName;
    }

    /**
     * 
     * @return The value
     */
    public String getValue() {
        return value;
    }

    /**
     * 
     * @param value
     *            The value
     */
    public void setValue(String value) {
        this.value = value;
    }

    @Override
    public String toString() {
        return "EachFieldDetail [fieldName=" + fieldName + ", value=" + value
                + "]";
    }
}

Answer 3

使用您的模型和以下代码我没有发现任何错误：

    String str="[{\"fieldName\":\"siteName\",\"value\":\"Warehouse\"},{\"fieldName\":\"poNumber\",\"value\":\"po1\"},{\"fieldName\":\"itemCode\",\"value\":\"itemcode1\"},{\"fieldName\":\"asdnSerialNo\",\"value\":\"null\"}]";
    ObjectMapper map=new ObjectMapper();
    JsonNode node=map.readTree(str);

com.fasterxml.jackson.databind.JsonMappingException：无法反序列化 START_ARRAY 令牌

com.fasterxml.jackson.databind.JsonMappingException: Can not deserialize out of START_ARRAY token

java

json

jackson