Gson:java.lang.StackOverflowError:空 [英] Gson:java.lang.StackOverflowError: null

问题描述

我有一个Delete类，我想使用Gson库将其转换为json，但是当我转换它时，它会抛出java.lang.StackOverflowError: null的异常 这是我的课

i have a class Delete which i want to convert it into json using Gson library but when i convert it it throws exception of java.lang.StackOverflowError: null here is my class

import models.UserNotifications.MailMessages.DeleteReason._
import models.UserNotifications.MailMessages.DeleteStatus._

@SerialVersionUID(1)
class Delete extends Serializable {

  var deleteStatus : DeleteStatus = DELETED
  var deleteReason : DeleteReason = EXPIRED

  /*
   * Setters
   */

  def setDeleteStatus(deletestatus : String)= {
    deleteStatus = DeleteStatus.withName(deletestatus)
  } 
  def setDeleteReason ( deletereason : String) ={
    deleteReason = DeleteReason.withName(deletereason)
  }

  /*
   * Getter
   */

  def getDeleteStatus : DeleteStatus = {
    deleteStatus
  }
  def getDeleteReason : DeleteReason = {
    deleteReason
  }


}

这是枚举类 DeleteStatus.scala

here is enumeration classes DeleteStatus.scala

object DeleteStatus extends Enumeration {

  type DeleteStatus = Value
  val DELETED, ACTIVE = Value

}

DeleteReason.scala

DeleteReason.scala

object DeleteReason extends Enumeration{
  type DeleteReason = Value
  val EXPIRED , MANUALLY_DELETED = Value
}

这是我在Json中进行转换的方式

Here is how i am converting in Json

var delete = new Delete

    val gson = new Gson();
    val g=gson.toJson(delete)

但它引发以下异常

java.lang.StackOverflowError: null
    at com.google.gson.reflect.TypeToken.equals(TypeToken.java:284) ~[gson-2.3.1.jar:na]
    at java.util.HashMap.getNode(HashMap.java:571) ~[na:1.8.0_45]
    at java.util.HashMap.get(HashMap.java:556) ~[na:1.8.0_45]
    at java.util.Collections$SynchronizedMap.get(Collections.java:2584) ~[na:1.8.0_45]
    at com.google.gson.Gson.getAdapter(Gson.java:335) ~[gson-2.3.1.jar:na]
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:55) ~[gson-2.3.1.jar:na]
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:99) ~[gson-2.3.1.jar:na]
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:219) ~[gson-2.3.1.jar:na]
    at com.google.gson.internal.bind.TypeAdapterRuntimeTypeWrapper.write(TypeAdapterRuntimeTypeWrapper.java:68) ~[gson-2.3.1.jar:na]
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$1.write(ReflectiveTypeAdapterFactory.java:99) ~[gson-2.3.1.jar:na]
    at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.write(ReflectiveTypeAdapterFactory.java:219) ~[gson-2.3.1.jar:na]

请帮助解决其中的问题

推荐答案

问题是Scala枚举的字节码包含可能值的集合-每个值都是枚举的一个实例.

The issue is that the bytecode of a Scala Enumeration contains a collection of the possible values - each of which is an instance of the enumeration.

例如，如果我们在以下计算机上运行javap CoinFaces:

For example, if we run javap CoinFaces on:

object CoinFaces extends Enumeration {
  type CoinFaces = Value
  val Heads, Tails = Value
}

我们可以看到Java反汇编包含类型为Enumeration$Value的静态字段values:

we can see that the Java disassembly contains static field values of type Enumeration$Value:

public final class CoinFaces {
  public static scala.Enumeration$Value Tails();
  public static scala.Enumeration$Value Heads();
  public static scala.Enumeration$ValueSet$ ValueSet();
  public static scala.Enumeration$ValueOrdering$ ValueOrdering();
  public static scala.Enumeration$Value withName(java.lang.String);
  public static scala.Enumeration$Value apply(int);
  public static int maxId();
  public static scala.Enumeration$ValueSet values();
  public static java.lang.String toString();
}

这意味着从Java开始，所有Scala枚举都包含循环引用.最简单的解决方案是对诸如@transient( https://stackoverflow.com/a/14489534/323177).不幸的是，由于我们无法为您的自定义Scala Enumeration注释生成的字节码，因此解决方案是创建一个自定义GSON序列化程序，该序列化程序将枚举值手动序列化为String.

This means that from Java, all Scala enumerations contains cyclical references. The easiest solution to this is to annotate such fields as @transient (https://stackoverflow.com/a/14489534/323177). Unfortunately, since we cannot annotate the generated bytecode for your custom Scala Enumeration, the solution is to create a custom GSON serializer that manually serializes the enumeration value as a String.

import com.google.gson.JsonElement;
import com.google.gson.JsonPrimitive;
import com.google.gson.JsonSerializationContext;
import com.google.gson.JsonSerializer;
import scala.Enumeration;

import java.lang.reflect.Type;

// Scala enumerations are static Java classes with values of type `Enumeration.Value`
public class GsonScalaEnumerationSerializer implements JsonSerializer<Enumeration.Value> {
  @Override
  public JsonElement serialize(final Enumeration.Value enumValue,
                               final Type typeOfEnum,
                               final JsonSerializationContext context) {

    return new JsonPrimitive(enumValue.toString());
  }
}

然后在构造Gson对象的过程中将其注册为类型适配器，然后将序列化Enumeration值.

Then register this as a type adapter during construction of your Gson object and this will then serialise the Enumeration value.

Gson gson = new GsonBuilder()
    .registerTypeAdapter(Enumeration.Value.class, new GsonScalaEnumerationSerializer())
    .create();

这篇关于Gson:java.lang.StackOverflowError:空的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！