运行时 GSON 对象类型转换

Question

我有一个模板对象类型 ExternalActionReqBean 有一个对象，可以通过指示操作字段设置任何类让我们说，如果 action="FROZEN" ， ExternalActionReqBean->payload 将使用 ExternalActionFrozenReqBean 类类型，如果 action="UNFROZEN" ExternalActionUnFrozenReqBean 类类型将被使用。如果有效载荷如下所示，实现这一目标的最佳实践是什么？{"txnID":"txn","action":"FROZEN","resource":"PNSENDER","payload":{"msisdn_list":["xxxx","xxx","xxx"]}}ExternalActionReqBean externalActionReqBean = GSON.fromJson(payload, ExternalActionReqBean.class);             if("FROZEN".equals(externalActionReqBean.getAction())){               // externalActionFrozenReqBean = GSON.fromJson(externalActionReqBean.getPayload(),ExternalActionFrozenReqBean.class);             }@Data@AllArgsConstructorpublic class ExternalActionReqBean {   private String txnID;   private String action;   private String resource;   private Object payload;}@Datapublic class ExternalActionFrozenReqBean {   private List<String> msisdn_list;}@Datapublic class ExternalActionUnFrozenReqBean {   private String result;}

Answer 1

我已经更改了 ExternalActionReqBean 类签名，它的类型被转换为通用，而不是使用 TypeToken 如下。

@Data

@AllArgsConstructor

public class ExternalActionReqBean<T> {

   private String txnID;

   private String action;

   private String resource;

   private T payload;

}

代码：

 if ("FROZEN".equals(externalActionReqBean.getAction())) {

  Type complexType = new TypeToken<ExternalActionReqBean<ExternalActionFrozenReqBean>>() {}.getType();

  ExternalActionReqBean<ExternalActionFrozenReqBean> result = GSON.fromJson(payload, complexType);

}

感谢https://futurestud.io/tutorials/gson-advanced-generics，您可以在“泛型反序列化”下找到更多信息