使用Gson反序列化Java 8 LocalDateTime

Question

我有一个日期时间属性的JSON,格式为"2014-03-10T18:46:40.000Z",我想使用Gson将其反序列化为java.time.LocalDateTime字段.

当我尝试反序列化时,我收到错误:

java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING

Answer 1

当您反序列化LocalDateTime属性时发生错误,因为GSON无法解析属性的值,因为它不知道LocalDateTime对象.

使用GsonBuilder的registerTypeAdapter方法定义自定义LocalDateTime适配器.以下代码段将帮助您反序列化LocalDateTime属性.

Gson gson = new GsonBuilder().registerTypeAdapter(LocalDateTime.class, new JsonDeserializer<LocalDateTime>() {
    @Override
    public LocalDateTime deserialize(JsonElement json, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {
        Instant instant = Instant.ofEpochMilli(json.getAsJsonPrimitive().getAsLong());
        return LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
    }
}).create();

Answer 2

要扩展@Randula的答案,要将分区日期时间字符串(2014-03-10T18:46:40.000Z)解析为JSON:

Gson gson = new GsonBuilder().registerTypeAdapter(LocalDateTime.class, new JsonDeserializer<LocalDateTime>() {
@Override
public LocalDateTime deserialize(JsonElement json, Type type, JsonDeserializationContext jsonDeserializationContext) throws JsonParseException {
    return ZonedDateTime.parse(json.getAsJsonPrimitive().getAsString()).toLocalDateTime();
}
}).create();

Answer 3

甚至进一步扩展@Evers答案:

您可以使用lambda进一步简化:

GSON GSON = new GsonBuilder().registerTypeAdapter(LocalDateTime.class, (JsonDeserializer<LocalDateTime>) (json, type, jsonDeserializationContext) ->
    ZonedDateTime.parse(json.getAsJsonPrimitive().getAsString()).toLocalDateTime()).create();

Answer 4

以下对我有用。

爪哇：

Gson gson = new GsonBuilder().registerTypeAdapter(LocalDateTime.class, new JsonDeserializer<LocalDateTime>() { 
@Override 
public LocalDateTime deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context) throws JsonParseException { 

return LocalDateTime.parse(json.getAsString(), DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm")); } 

}).create();

Test test = gson.fromJson(stringJson, Test.class);

其中stringJson是存储为 String 类型的 Json

杰森：

"dateField":"2020-01-30 15:00"

其中dateField是LocalDateTime类型，存在于 stringJson 字符串变量中。