问题：使用 Jersey 进行序列化，使用 gson 反序列化 JSON

Question

我一直在为 REST API 使用 Jersey 并返回 JSON。在客户端我使用google-gson。在反序列化 JSON 时，出现以下错误。

com.google.gson.JsonParseException: The JsonDeserializer MapTypeAdapter failed to deserialized json object {} given the type interface java.util.Map
        at com.google.gson.JsonDeserializerExceptionWrapper.deserialize(JsonDeserializerExceptionWrapper.java:63)
        at com.google.gson.JsonDeserializationVisitor.invokeCustomDeserializer(JsonDeserializationVisitor.java:88)
        at com.google.gson.JsonObjectDeserializationVisitor.visitFieldUsingCustomHandler(JsonObjectDeserializationVisitor.java:116)
        at com.google.gson.ObjectNavigator.navigateClassFields(ObjectNavigator.java:158)
        at com.google.gson.ObjectNavigator.accept(ObjectNavigator.java:131)
        at com.google.gson.JsonDeserializationCo

由 Jersey 序列化为 JSON 的对象具有非泛型（未指定类型）映射和列表

public class Dealer implements Serializable
{
  private String serviceURL;
  private Map hoursService;
  List dealerAttributes;  
}

这是 Jersey 生成的 JSON

{"serviceURL":www.google.com,"hoursService":{"3":{"dayOfWeek":3,"closeTime":"6:30 PM","openTime":"7:30 AM"},"2":{"dayOfWeek":2,"closeTime":"6:30 PM","openTime":"7:30 AM"},"1":{"dayOfWeek":1,"closeTime":"6:30 PM","openTime":"7:30 AM"}},"dealerAttributes":[{"language":"English","dealerAttributeName":"Spanish Speaking","updateDate":1174971061000},{"language":"English","updateDate":1103003316000}]}

可能是什么原因。请帮我解决这个问题。还有其他比gson更好的实用程序吗？请提出建议。

谢谢。

Answer 1

示例 JSON 无效。 http://jsonlint.com

www.google.com 必须用引号括起来。那么它是有效的。

纠正 JSON 后，以下反序列化示例输出

[经销商：serviceURL=www.google.com, hoursService={
1=[时间：dayOfWeek=1，closeTime=6:30 PM，openTime=7:30 AM]，
2=[时间：dayOfWeek=2，closeTime=6:30 PM，openTime=7:30 AM]，
3=[时间：dayOfWeek=3，closeTime=6:30 PM，openTime=7:30 AM]}，
经销商属性=[
[DealerAttributes：语言=英语，dealerAttributeName=西班牙语，更新日期=1174971061000]，
[DealerAttributes：语言=英语，dealerAttributeName=null，updateDate=1103003316000]]]

public class Foo
{
  static String jsonInput = 
    "{" + 
      "\"serviceURL\":\"www.google.com\"," + 
      "\"hoursService\":" +
      "{" + 
        "\"1\":" +
        "{" + 
          "\"dayOfWeek\":1," + 
          "\"closeTime\":\"6:30 PM\"," + 
          "\"openTime\":\"7:30 AM\"" + 
        "}," + 
        "\"2\":" +
        "{" + 
          "\"dayOfWeek\":2," + 
          "\"closeTime\":\"6:30 PM\"," + 
          "\"openTime\":\"7:30 AM\"" + 
        "}," + 
        "\"3\":" +
        "{" + 
          "\"dayOfWeek\":3," + 
          "\"closeTime\":\"6:30 PM\"," + 
          "\"openTime\":\"7:30 AM\"" + 
        "}" + 
      "}," + 
      "\"dealerAttributes\":" +
      "[" + 
        "{" + 
          "\"language\":\"English\"," + 
          "\"dealerAttributeName\":\"Spanish Speaking\"," + 
          "\"updateDate\":1174971061000" + 
        "}," + 
        "{" + 
          "\"language\":\"English\"," + 
          "\"updateDate\":1103003316000" + 
        "}" + 
      "]" + 
    "}";

  public static void main(String[] args)
  {
    GsonBuilder gsonBuilder = new GsonBuilder();
    Gson gson = gsonBuilder.create();
    Dealer dealer = gson.fromJson(jsonInput, Dealer.class);
    System.out.println(dealer);
  }
}

class Dealer
{
  private String serviceURL;
  private Map<String, Hours> hoursService;
  private List<DealerAttributes> dealerAttributes;

  @Override
  public String toString()
  {
    return String.format(
      "[Dealer: serviceURL=%1$s, hoursService=%2$s, dealerAttributes=%3$s]",
      serviceURL, hoursService, dealerAttributes);
  }
}

class Hours
{
  private int dayOfWeek;
  private String closeTime;
  private String openTime;

  @Override
  public String toString()
  {
    return String.format(
      "[Hours: dayOfWeek=%1$d, closeTime=%2$s, openTime=%3$s]",
      dayOfWeek, closeTime, openTime);
  }
}

class DealerAttributes
{
  private String language;
  private String dealerAttributeName;
  private long updateDate;

  @Override
  public String toString()
  {
    return String.format(
      "[DealerAttributes: language=%1$s, dealerAttributeName=%2$s, updateDate=%3$d]",
      language, dealerAttributeName, updateDate);
  }
}

这确实使用了泛型类型，我知道你说你没有使用它来序列化，但是你在反序列化时是否遇到了同样的限制？如果是这样，那么您将不得不实施更多“手动”反序列化解析，因为正如文档所说，"[w]hile deserializing, Collection must be of a specific generic type"。