Gson.fromJson() - 如果Type不同则抛出异常

Question

我已经创建了REST服务,ExceptionEntity如果出现问题,它会返回序列化的类.

如果应该反序列化的json Gson.fromJson()是不同的类型,我想抛出一些异常.例如,我有这个字符串应该反序列化(my.ExceptionEntity.class):

{"exceptionId":2,"message":"Room aaaa already exists."}

但我使用Roomclass作为此序列化字符串的类型:

String json = "{\"exceptionId\":2,\"message\":\"Room aaaa already exists.\"}";
Room r = gson.fromJson(json, Room.class);
// as a result r==null but I want to throw Exception; how?

[编辑] 我测试了这个,它不起作用:

try {
    return g.fromJson(roomJson, new TypeToken<Room>(){}.getType());
    // this also doesn't work
    // return g.fromJson(roomJson, Room.class);
} catch (JsonSyntaxException e) {
    pepuch.multiplayergame.entity.Exception ex = g.fromJson(roomJson, pepuch.multiplayergame.entity.Exception.class);
    throw ExceptionController.toGameServerException(ex);
} catch (JsonParseException e) {
    pepuch.multiplayergame.entity.Exception ex = g.fromJson(roomJson, pepuch.multiplayergame.entity.Exception.class);
    throw ExceptionController.toGameServerException(ex);
}

Answer 1

根据GSon 文档,如果根据您提供的类型无法反序列化json流,则会抛出异常:

抛出: JsonParseException- 如果json不是classOfT类型的对象的有效表示

但是这是一个未经检查的异常,如果你想提供一个你应该尝试的自定义异常

try {
  Room r = gson.fromJson(json, Room.class);
}
catch (JsonParseException e) {
  throw new YourException();
}