java - Scala - InvalidClassException : no valid constructor

Question

我在 Scala 中创建了 Guava 的 ImmutableRangeMap 和 Builder 的 Serializable 版本，以便在我的 Spark 应用程序中使用。我的 SerializableImmutableRangeMap 中也有一个零参数构造函数，那么为什么我在运行我的 Spark 应用程序时会得到 InvalidClassException: no valid constructor？

这是我的 SerializableImmutableRangeClass 对象和类:

object SerializableImmutableRangeMap extends Serializable {
  final class SerializableBuilder[K <: Comparable[_], V]() extends Serializable {
    val keyRanges: RangeSet[K] = TreeRangeSet.create()
    val rangeMap: RangeMap[K, V] = TreeRangeMap.create()

    def put(range: Range[K], value: V): SerializableBuilder[K, V] = {
      checkNotNull(range)
      checkNotNull(value)
      checkArgument(!range.isEmpty(), "Range must not be empty, but was %s", range)
      if (!keyRanges.complement().encloses(range)) {
        // it's an error case; we can afford an expensive lookup
        for (entry: Entry[Range[K], V] <- JavaConversions.asScalaSet(rangeMap.asMapOfRanges().entrySet())) {
          val key: Range[K] = entry.getKey()
          if (key.isConnected(range) && !key.intersection(range).isEmpty()) {
            throw new IllegalArgumentException(
                "Overlapping ranges: range " + range + " overlaps with entry " + entry)
          }
        }
      }
      keyRanges.add(range)
      rangeMap.put(range, value)
      this
    }

    def putAll(rangeMap: RangeMap[K, _ <: V]): SerializableBuilder[K, V] = {
      for (entry <- JavaConversions.asScalaSet(rangeMap.asMapOfRanges().entrySet())) {
        put(entry.getKey(), entry.getValue())
      }
      this
    }

    def build(): SerializableImmutableRangeMap[K, V] ={
      val map: java.util.Map[Range[K], V] = rangeMap.asMapOfRanges()
      val rangesBuilder: ImmutableList.Builder[Range[K]] = new ImmutableList.Builder[Range[K]](map.size())
      val valuesBuilder: ImmutableList.Builder[V] = new ImmutableList.Builder[V](map.size())
      for (entry: Entry[Range[K], V] <- JavaConversions.asScalaSet(map.entrySet())) {
        rangesBuilder.add(entry.getKey())
        valuesBuilder.add(entry.getValue())
      }
      return new SerializableImmutableRangeMap[K, V](rangesBuilder.build(), valuesBuilder.build())
    }
  }

def builder[K <: Comparable[_], V](): SerializableBuilder[K, V] = {
    new SerializableBuilder[K, V]()
  }
}

class SerializableImmutableRangeMap[K <: Comparable[_], V](ranges: ImmutableList[Range[K]], values: ImmutableList[V]) extends ImmutableRangeMap[K, V](ranges, values) with Serializable {
  def this() {
    this(ImmutableList.of(), ImmutableList.of())
  }
}

和堆栈跟踪:

java.io.InvalidClassException: com.google.common.collect.SerializableImmutableRangeMap; no valid constructor
        at java.io.ObjectStreamClass$ExceptionInfo.newInvalidClassException(ObjectStreamClass.java:150)
        at java.io.ObjectStreamClass.checkDeserialize(ObjectStreamClass.java:768)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1775)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1993)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1918)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1993)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1918)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1993)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1918)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1993)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1918)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
        at java.io.ObjectInputStream.readArray(ObjectInputStream.java:1707)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1345)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1993)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1918)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1993)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1918)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1993)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1918)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:371)
        at scala.collection.immutable.$colon$colon.readObject(List.scala:362)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:483)
        at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1896)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1993)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1918)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
        at java.io.ObjectInputStream.defaultReadFields(ObjectInputStream.java:1993)
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1918)
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1801)
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1351)
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:371)
        at org.apache.spark.serializer.JavaDeserializationStream.readObject(JavaSerializer.scala:68)
        at org.apache.spark.serializer.JavaSerializerInstance.deserialize(JavaSerializer.scala:94)
        at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:60)
        at org.apache.spark.scheduler.ShuffleMapTask.runTask(ShuffleMapTask.scala:41)
        at org.apache.spark.scheduler.Task.run(Task.scala:64)
        at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:203)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)

Answer 1

Serializable 文档的相关部分:

To allow subtypes of non-serializable classes to be serialized, the subtype may assume responsibility for saving and restoring the state of the supertype's public, protected, and (if accessible) package fields. The subtype may assume this responsibility only if the class it extends has an accessible no-arg constructor to initialize the class's state. It is an error to declare a class Serializable if this is not the case. The error will be detected at runtime.

您的父类(super class) (ImmutableRangeMap) 没有无参数构造函数，也不是Serializable。这就是问题。 Serializable 类(例如 SerializableImmutableRangeMap)不需要无参数构造函数。