Java使用datetime反序列化JSON到对象

Question

我有个问题。我有以下JSON：

[
   {
      "Id":"8",
      "MasterAgentId":"0",
      "LastAgentStrategyId":"16116488969159",
      "BotState":"Active",
      "Owner":"Andre",
      "ExtraNotifiers":"",
      "Exchange":"lava",
      "DateTime":"2021-01-27 22:12:02",
      "AgentStatus":"Enabled",
      "ProtectiveOrdersEnabled":"yes",
      "Sim_Progress":"100",
      "Sim_DateTime":"2021-01-27 09:18:00",
      "Sim_Coin":"BTC",
      "Sim_Price":"31626.580000",
      "Sim_Profit":"1216.04",
      "Sim_Profit_Perc":"60.80",
      "Sim_StartDateTime":"2019-01-01 00:00:00",
      "LastAgentStrategyRun":"2020-12-19 17:40:30.531000"
   }
]

如您所见，我在JSON中有4个日期时间：DateTime, Sim_DateTime, Sim_StartDateTime, LastAgentStrategyRun

现在，我为此创建了一个类，如下所示：

import java.time.LocalDateTime;

public class Agent {

    private int Id;
    private int MasterAgentId;
    private long LastAgentStrategyId;
    private AgentBotState BotState;
    private String Owner;
    private String ExtraNotifiers;
    private AgentExchanges Exchange;
    private LocalDateTime DateTime;
    private AgentStatus AgentStatus;
    private String ProtectiveOrdersEnabled;
    private String Sim_Progress;
    private String Sim_DateTime;
    private String Sim_Coin;
    private double Sim_Price;
    private double Sim_Profit;
    private double Sim_Profit_Perc;
    private LocalDateTime Sim_StartDateTime;
    private LocalDateTime LastAgentStrategyRun;
}

但是当我使用GSON反序列化json时：

Gson gson = new Gson();
Type listType = new TypeToken<ArrayList<Agent>>() {}.getType();
ArrayList<Agent> agentList = new Gson().fromJson(jsonResponse, listType);

我得到以下错误：

但代码崩溃，出现以下错误：

Exception in thread "main" com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 157 path $[0].DateTime
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:200)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:103)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:196)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
    at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:81)
    at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60)
    at com.google.gson.Gson.fromJson(Gson.java:810)
    at com.google.gson.Gson.fromJson(Gson.java:775)
    at com.google.gson.Gson.fromJson(Gson.java:724)
    at com.company.Main.main(Main.java:34)
Caused by: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 157 path $[0].DateTime
    at com.google.gson.stream.JsonReader.beginObject(JsonReader.java:387)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:189)
    ... 9 more

现在，当我从json中删除所有datetimes时，它会正确解析，只有几个奇怪的警告：

WARNING: An illegal reflective access operation has occurred WARNING: Illegal reflective access by com.google.gson.internal.bind.ReflectiveTypeAdapterFactory (file:/C:/Users/Alexander/.m2/repository/com/google/code/gson/gson/2.3.1/gson-2.3.1.jar) to field java.time.LocalDateTime.date WARNING: Please consider reporting this to the maintainers of com.google.gson.internal.bind.ReflectiveTypeAdapterFactory WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations WARNING: All illegal access operations will be denied in a future release

如何将datetime字符串解析为对象，以及如何消除警告

更新

使用以下代码后：

Gson gson = new GsonBuilder().registerTypeAdapter(LocalDateTime.class, (JsonDeserializer<LocalDateTime>) (json, type, jsonDeserializationContext) -> {
    Instant instant = Instant.ofEpochMilli(json.getAsJsonPrimitive().getAsLong());
    return LocalDateTime.ofInstant(instant, ZoneId.systemDefault());
}).create();

Type listType = new TypeToken<ArrayList<Agent>>() {}.getType();
ArrayList<Agent> agentList = gson.fromJson(jsonResponse, listType);

我现在得到这个错误：

Exception in thread "main" java.lang.NumberFormatException: For input string: "2021-01-27 22:56:01"
    at java.base/java.lang.NumberFormatException.forInputString(NumberFormatException.java:68)
    at java.base/java.lang.Long.parseLong(Long.java:707)
    at java.base/java.lang.Long.parseLong(Long.java:832)
    at com.google.gson.JsonPrimitive.getAsLong(JsonPrimitive.java:238)
    at com.company.Main.lambda$main$0(Main.java:35)
    at com.google.gson.TreeTypeAdapter.read(TreeTypeAdapter.java:58)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:103)
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:196)
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.read(TypeAdapterRuntimeTypeWrapper.java:40)
    at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:81)
    at com.google.gson.internal.bind.CollectionTypeAdapterFactory$Adapter.read(CollectionTypeAdapterFactory.java:60)
    at com.google.gson.Gson.fromJson(Gson.java:810)
    at com.google.gson.Gson.fromJson(Gson.java:775)
    at com.google.gson.Gson.fromJson(Gson.java:724)
    at com.company.Main.main(Main.java:40)

Answer 1

您需要注册LocalDateTime:e.replace Gson gson = new Gson();参见下面的代码：

更新了使用日期格式化程序解析LocalDateTime的答案，而不是创建即时消息。此外，您的日期格式也不一致，因为有些返回秒，有些返回毫秒，所以我提供了两种格式选择

请参阅使用简化代理类的示例代码

String jsonResponse = "[\n" +
            "   {\n" +
            "      \"DateTime\":\"2021-01-27 09:18:00\",\n" +
            "      \"Sim_StartDateTime\":\"2019-01-01 00:00:00\",\n" +
            "      \"LastAgentStrategyRun\":\"2020-12-19 17:40:30.531000\"\n" +
            "   }\n" +
            ']';

    Gson gson = new GsonBuilder().registerTypeAdapter(LocalDateTime.class, (JsonDeserializer<LocalDateTime>) (json, type, jsonDeserializationContext) -> {

        try{
            return LocalDateTime.parse(json.getAsJsonPrimitive().getAsString(), DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss"));
        } catch (DateTimeParseException e){
            return LocalDateTime.parse(json.getAsJsonPrimitive().getAsString(), DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss.SSSSSS"));
        }

    }).create();

    Type listType = new TypeToken<ArrayList<Agent>>() {}.getType();
    ArrayList<Agent> agentList = gson.fromJson(jsonResponse, listType);

    System.out.println(agentList);

还有特工班

public class Agent {
    private LocalDateTime DateTime;
    private LocalDateTime Sim_StartDateTime;
    private LocalDateTime LastAgentStrategyRun;

    public LocalDateTime getDateTime() {
        return DateTime;
    }

    public void setDateTime(LocalDateTime dateTime) {
        DateTime = dateTime;
    }

    public LocalDateTime getSim_StartDateTime() {
        return Sim_StartDateTime;
    }

    public void setSim_StartDateTime(LocalDateTime sim_StartDateTime) {
        Sim_StartDateTime = sim_StartDateTime;
    }

    public LocalDateTime getLastAgentStrategyRun() {
        return LastAgentStrategyRun;
    }

    public void setLastAgentStrategyRun(LocalDateTime lastAgentStrategyRun) {
        LastAgentStrategyRun = lastAgentStrategyRun;
    }

    @Override
    public String toString() {
        return "Agent{" +
                "DateTime=" + DateTime +
                ", Sim_StartDateTime=" + Sim_StartDateTime +
                ", LastAgentStrategyRun=" + LastAgentStrategyRun +
                '}';
    }
}

以及输出

[Agent{DateTime=2021-01-27T09:18, Sim_StartDateTime=2019-01-01T00:00, LastAgentStrategyRun=2020-12-19T17:40:30.531}]

Answer 2

你可以使用GsonUtils。但请注意以下问题：在这个字段中，日期/时间格式不同。这是不正确的，因为要解析此字段，必须使用所需的模板设置日期/时间格式化程序。我改变了LastAgentStrategyRun字段中的格式，这是一个例子：

String json = "[\n" +
        "   {\n" +
        "      \"Id\":\"8\",\n" +
        "      \"MasterAgentId\":\"0\",\n" +
        "      \"LastAgentStrategyId\":\"16116488969159\",\n" +
        "      \"BotState\":\"Active\",\n" +
        "      \"Owner\":\"Andre\",\n" +
        "      \"ExtraNotifiers\":\"\",\n" +
        "      \"Exchange\":\"lava\",\n" +
        "      \"DateTime\":\"2021-01-27 22:12:02\",\n" +
        "      \"AgentStatus\":\"Enabled\",\n" +
        "      \"ProtectiveOrdersEnabled\":\"yes\",\n" +
        "      \"Sim_Progress\":\"100\",\n" +
        "      \"Sim_DateTime\":\"2021-01-27 09:18:00\",\n" +
        "      \"Sim_Coin\":\"BTC\",\n" +
        "      \"Sim_Price\":\"31626.580000\",\n" +
        "      \"Sim_Profit\":\"1216.04\",\n" +
        "      \"Sim_Profit_Perc\":\"60.80\",\n" +
        "      \"Sim_StartDateTime\":\"2019-01-01 00:00:00\",\n" +
        "      \"LastAgentStrategyRun\":\"2020-12-19 17:40:30\"\n" +
        "   }\n" +
        ']';

DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyy-MM-dd HH:mm:ss");
GsonDecorator gson = GsonHelper.createGsonDecorator(new GsonBuilderDecorator().withDateTimeFormatter(formatter));
List<Agent> agent = gson.readList(json, Agent.class);