仅在特定字段上使用自定义解串器？ [英] Use a custom deserializer only on certain fields?

问题描述

使用gson，是否可以在特定的字段上使用自定义的解串器/序列化器？ 用户指南显示了如何为整个类型注册适配器，而不是针对特定领域。我之所以要这样做，是因为我解析了一个自定义日期格式并将其存储在 long 成员字段中（作为Unix时间戳），所以我不想注册所有 Long 字段的类型适配器。

有没有办法做到这一点？

解决方案

我还将日期值存储为我的对象中的 long ，以方便防御性复制。我还希望在序列化对象时仅覆盖日期字段，而不必写出流程中的所有字段。这是我想出的解决方案。不知道这是处理这种情况的最佳方式，但它似乎表现得很好。

DateUtil 类是一个自定义类，用于获取 Date 解析为字符串。

  public final class Person {
 private final String firstName; 
 private final String lastName; 
私人最后的出生日期; 
 
私人人物（字符串firstName，字符串lastName，日期birthDate）{
 this.firstName = firstName; 
 this.lastName = lastName; 
 this.birthDate = birthDate.getTime（）; 
} 
 
 public static Person Person getInstance（String firstName，String lastName，Date birthDate）{
 return new Person（firstName，lastName，birthDate）; 
 
 $ b $ public String toJson（）{
 return new GsonBuilder（）。registerTypeAdapter（Person.class，new PersonSerializer（））。create（）。toJson（this）; 
} 
 
 public static class PersonSerializer实现JsonSerializer< Person> {
 @Override 
 public JsonElement serialize（Person person，Type type，JsonSerializationContext context）{
 JsonElement personJson = new Gson（）。toJsonTree（person）; 
 personJson.getAsJsonObject（）。add（birthDate，new JsonPrimitive（DateUtil.getFormattedDate（new Date（policy.birthDate），DateFormat.USA_DATE）））; 
 return personJson; 
 
 
 
 
 
 
当这个类被序列化时，  birthDate 字段以格式化字符串而不是 long 值。
 
With gson, is it possible to use a custom deserializer / serializer only on certain fields? The user guide shows how to register an adapter for an entire type, not for specific fields. The reason why I want this is because I parse a custom date format and store it in a long member field (as a Unix timestamp), so I don't want to register a type adapter for all Long fields.

Is there a way to do this?
解决方案
I also store Date values as long in my objects for easy defensive copies. I also desired a way to override only the date fields when serializing my object and not having to write out all the fields in the process. This is the solution I came up with. Not sure it is the optimal way to handle this, but it seems to perform just fine.

The DateUtil class is a custom class used here to get a Date parsed as a String.
public final class Person {
  private final String firstName;
  private final String lastName;
  private final long birthDate;

  private Person(String firstName, String lastName, Date birthDate) {
    this.firstName = firstName;
    this.lastName = lastName;
    this.birthDate = birthDate.getTime();
  }

  public static Person getInstance(String firstName, String lastName, Date birthDate) {
    return new Person(firstName, lastName, birthDate);
  }

  public String toJson() {
    return new GsonBuilder().registerTypeAdapter(Person.class, new PersonSerializer()).create().toJson(this);
  }

  public static class PersonSerializer implements JsonSerializer<Person> {
    @Override
    public JsonElement serialize(Person person, Type type, JsonSerializationContext context) {
      JsonElement personJson = new Gson().toJsonTree(person);
      personJson.getAsJsonObject().add("birthDate", new JsonPrimitive(DateUtil.getFormattedDate(new Date(policy.birthDate), DateFormat.USA_DATE)));
      return personJson;
    }
  }
}
When the class is serialized, the birthDate field is returned as a formatted String instead of the long value.

                        
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