如何使用嵌套的JSONString从JSON创建POJO

Question

目前我的代码正在接收带有

主体的POST请求

{
  "EventBody": {
    "message":"{\"sysData\":{\"time\":1520865496235,\"data\":{\"appUUID\":\"randomnumber\",\"userId\":\"1801\"}},\"appData\":{\"testMessage\":\"Stuff to see\",\"ackURL\":\"http:localhost/generic\"\"}}",
    "client": {
      "device": {
        "device-id": 12345
      }
    }
  }
}

如果被转换为这样的pojo对象，该身体

@JsonIgnoreProperties(ignoreUnknown = true)
public class EventBody {

    // If state message object as type string I do get the string, if 
    // I keep it GenericMessage object I am met with a null object.
    @JsonProperty("message")
    public GenericMessage message;

    @JsonIgnoreProperties(ignoreUnknown = true)
    public class GenericMessage {

        @JsonProperty("sysData")
        public SysData sysData;
        @JsonProperty("appData")
        public AppData appData;

        public class SysData {
            public String time;
            public Data data;

            public class Data {
                public String appUUID;
                public Integer userId;
            }
        }

        public class AppData {
            public String ackURL;
        }
    }

    @JsonProperty("client")
    public Client client;

    public class Client {

        @JsonProperty("device")
        public Device device;

        @JsonIgnoreProperties(ignoreUnknown = true)
        public class Device {
            @JsonProperty("device-id")
            public Integer deviceId;
        }
    }
}

我遇到了如何解析格式化为JSON对象的/ delimited字符串的问题。通过将GenericMessage类移动到它自己的单独类中并由服务类用于使用此方法解析它，我已经有了它的工作。

public GenericMessage convertGenericMessage(String message) throws MessageException {
    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
    try {
        if(message != null) {
            GenericMessage foundMessage = objectMapper.readValue(message, GenericMessage.class);
            return foundMessage;
        } else {
            throw new MessageException("Message field empty in event Object");
        }
    } catch (Exception e) {
        throw new MessageException("Exception while converting message to GenericMessage object: " + e.getMessage());
    }
}

但这有点难看并引入了我希望不必要的额外步骤。有没有办法为GenericMessage调用某种隐式构造函数，以便解析JSONString对象？