Jackson MismatchedInputException否要从字符串值反序列化的字符串参数构造函数/工厂方法

问题描述

我有一个示例json：

Object json = "{\"known1\":\"m1234\",\"known2\":1,\"known3\":2,\"unknown1\":true,\"unknown2\":15}"

我的Pojo类如下：

@Data
@AllArgsConstructor
@NoArgsConstructor
@Builder
public class MyPojo implements Serializable {
   private String known1;
   private String known2;
   private String known3;
   
   private Map<String,Object> unknownFields;

@JsonAnySetter
public void setDynamicAttributes(String key,Object value) {
    if (this.unknownFields == null) {
        this.unknownFields = new HashMap<>();
    }
    this.unknownFields.put(key,value);
}}

以下是代码段：

Object jsonString = "{\"known1\":\"m1234\",\"unknown2\":15}";
    MyPojo poco = new ObjectMapper().**convertValue**(jsonString,MyPojo.class);
    System.out.println(screenInfo);

我正在例外：

Exception in thread "main" java.lang.IllegalArgumentException: Cannot construct instance of `com.model.MyPojo` (although at least one Creator exists): no String-argument constructor/factory method to deserialize from String value ('{"known1":"m1234","known2":1,"known3":2,"unknown1":true,"unknown2":15}')

但是当我使用

Object jsonString = "{\"known1\":\"m1234\",\"unknown2\":15}";
    MyPojo poco = new ObjectMapper().**readValue**(jsonString.toString(),MyPojo.class);
    System.out.println(screenInfo);

我得到了预期的输出，未知字段也填充在unknownFields映射中。谁能解释我为什么？我也想使其与convertValue一起使用。请帮忙。

解决方法

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