Java 找不到合适的创建者方法从JSON字符串反序列化

我在Spring应用程序中使用Jackson。当Jackson将我的JSON数据转换为对象时，它会给我一个错误

我的JSON数据是：

{“名称”：“sdfg”，“用户名”：“dfgdg”，“密码”：“dfgdg”，“类型”：“A”，“协议”：“1”，“说明”：“sdfsdfdsf”}

我的班级是：

public class Device extends Name {

    @Column
    private String username;

    @Column
    private String password;

    @JsonUnwrapped// I added this tag, not sure to use
    @ManyToOne
    private DeviceType type; 

    @JsonUnwrapped// I added this tag, not sure to use
    @ManyToOne
    private Protocol protocol;
    ...
    //description and name are fields at Name that Device extends
    //getters and setters

/* I tried that not sure:
 @JsonProperty("protocol")
    public void setProtocol(Protocol protocol) {
        this.protocol = protocol;
    }
*/
}

public class DeviceType extends Name {

    private List<Protocol> supportedProtocols;

    public List<Protocol> getSupportedProtocols() {
        return supportedProtocols;
    }

/*
I tried to add that:
@JsonProperty("type")
    @Override
    public void setName(String name) {
        super.setName(name);
    }
*/
}

public class Protocol extends Name {     
 /*
  Nothing at this method. I added that for my purpose:
  JsonProperty("protocol")
  @Override
  public void setName(String name) {
    super.setName(name);
  }
 */
}

---

异常准确地解释了问题所在：它不知道如何将字符串“A”转换为DeviceType类型的值。 最简单的方法是添加构造函数，如：

public DeviceType(String type) { .... }

一切都会好起来的。

试试这个，它会好起来的

{
        "name": "sdfg",
        "username": "dfgdg",
        "password": "dfgdg",
        "type": {"type_id":"1"},
        "protocol": {"protocol_id":"1"}
}

也许这是复制品？

{
        "name": "sdfg",
        "username": "dfgdg",
        "password": "dfgdg",
        "type": {"type_id":"1"},
        "protocol": {"protocol_id":"1"}
}