Gson自定义DateTime反序列化器

Question

我有一个JestClient（elasticsearch）响应，我试图将其反序列化为一个对象。该对象包含两个DateTime字段，而在响应中，它们是字符串，因此我得到：

com.google.gson.JsonSyntaxException: java.lang.IllegalStateException: Expected BEGIN_OBJECT but was STRING at line 1 column 102 path $.createdTimeStamp
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:226) ~[gson-2.8.5.jar:?]
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.read(ReflectiveTypeAdapterFactory.java:131) ~[gson-2.8.5.jar:?]
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:222) ~[gson-2.8.5.jar:?]
    at com.google.gson.Gson.fromJson(Gson.java:927) ~[gson-2.8.5.jar:?]
    at com.google.gson.Gson.fromJson(Gson.java:892) ~[gson-2.8.5.jar:?]
    at com.google.gson.Gson.fromJson(Gson.java:841) ~[gson-2.8.5.jar:?]
    at com.google.gson.Gson.fromJson(Gson.java:813) ~[gson-2.8.5.jar:?]
    at io.searchbox.client.JestResult.createSourceObject(JestResult.java:271) ~[Jest-6.x.jar:?]
    at io.searchbox.core.SearchResult.access$000(SearchResult.java:17) ~[Jest-6.x.jar:?]
    at io.searchbox.core.SearchResult$Hit.<init>(SearchResult.java:288) ~[Jest-6.x.jar:?]
    at io.searchbox.core.SearchResult.extractHit(SearchResult.java:163) ~[Jest-6.x.jar:?]
    at io.searchbox.core.SearchResult.getHits(SearchResult.java:92) ~[Jest-6.x.jar:?]
    at io.searchbox.core.SearchResult.getHits(SearchResult.java:73) ~[Jest-6.x.jar:?]
    at io.searchbox.core.SearchResult.getHits(SearchResult.java:65) ~[Jest-6.x.jar:?]
    at io.searchbox.core.SearchResult.getHits(SearchResult.java:61) ~[Jest-6.x.jar:?]

所以，我创建了一个自定义反序列化器来解决这个问题…然而，无论我做什么，我总是得到同样的错误。不知何故它没有注册使用它？

public final class DateTimeConverter extends TypeAdapter<DateTime> {

    @Override
    public void write(JsonWriter jsonWriter, DateTime dateTime) throws IOException {
        if (Objects.isNull(dateTime)) {
            jsonWriter.nullValue();
            return;
        }
        jsonWriter.value(dateTime.toString());
    }

    @Override
    public DateTime read(JsonReader jsonReader) throws IOException {
        System.out.println("This statement doesn't print, so I'm assuming this method isn't being used during parsing");
        String dateTimeString = jsonReader.nextString();
        return DateTime.parse(dateTimeString);
    }
}

    public JestClient getElasticsearchJestClient(@NonNull final AWSCredentialsProvider awsCredentialsProvider, @NonNull final Regions region) {
        Gson gson = new GsonBuilder().registerTypeAdapter(DateTime.class, new DateTimeConverter()).create();
        AESClientFactory factory = new AESClientFactory(awsCredentialsProvider, region.getName());
        factory.setHttpClientConfig(new HttpClientConfig.Builder(ENDPOINT)
                .multiThreaded(true)
                .gson(gson).build());
        return factory.getObject();
    }

最后，我试图解析JestClient响应的代码：

  List<SearchResult.Hit<MyObject, Void>> hits;
  SearchResult result = elasticsearchAccessor.getElasticsearchRecords(search);
  hits = result.getHits(MyObject.class);
  final List<MyObject> objects = hits.stream()
       .map((hit) -> hit.source)
       .collect(Collectors.toList());

无论我尝试什么，我总是得到上面的错误，我甚至不确定在这一点上调查什么--任何想法都被欣赏，我不确定还有什么可以尝试。

Answer 1

这个实现最终是正确的。它在我的测试中不起作用的原因是因为我需要将适配器添加到我正在初始化的Gson中：

    private static final Gson GSON = new GsonBuilder().registerTypeAdapter(ZonedDateTime.class, new DateTimeConverter()).create();