java - 使用 Gson 反序列化 LocalDateTime 不起作用

Question

我需要使用 Gson 将字符串转换为对象:

gson.fromJson("{\"message\":\"any msg.\",\"individual\":{\"id\":100,\"citizenshipList\":[{\"date\":[2018,10,15,16,29,36,402000000]}]}}", Response.class)

哪里

public class Response {
    private String message;
    private Individual individual;
}

public class Individual {
 private Integer id;
 private List<Citizenship> citizenshipList = new ArrayList<>();
}

public class Citizenship {

  @DateTimeFormat(pattern="d::MMM::uuuu HH::mm::ss")
  LocalDateTime date;

}

我收到此错误

java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 122 path $.individual.citizenshipList[0].date

我也尝试过修改后的 Gson :

Gson gson1 = new GsonBuilder()
            .registerTypeAdapter(LocalDateTime.class, new JsonDeserializer<LocalDateTime>() {
                @Override
                public LocalDateTime deserialize(JsonElement json, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {
                    JsonObject jo = json.getAsJsonObject();
                    return LocalDateTime.of(jo.get("year").getAsInt(),
                            jo.get("monthValue").getAsInt(),
                            jo.get("dayOfMonth").getAsInt(),
                            jo.get("hour").getAsInt(),
                            jo.get("minute").getAsInt(),
                            jo.get("second").getAsInt(),
                            jo.get("nano").getAsInt());
                }
            }).create();

但这给了我这个错误:

java.lang.IllegalStateException: Not a JSON Object: [2018,10,15,16,29,36,402000000]

Answer 1

您发布的两个错误说明了问题所在:

Not a JSON Object: [2018,10,15,16,29,36,402000000]

Expected BEGIN_OBJECT but was BEGIN_ARRAY

[2018,10,15,16,29,36,402000000] 是一个 JSON 数组，GSON 需要一个 JSON 对象，例如:{}。

解决此问题的一种方法是修改您的 JsonDeserializer 以使用 JsonArray 而不是 JsonObject:

Gson gson1 = new GsonBuilder()
            .registerTypeAdapter(LocalDateTime.class, new JsonDeserializer<LocalDateTime>() {
                @Override
                public LocalDateTime deserialize(JsonElement json, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {
                    JsonArray array = json.getJSONArray("date");
                    return LocalDateTime.of(
                                            // Set all values here from
                                            // `array` variable
                                            );
                }
            }).create();