Elasticsearch-Spark序列化不适用于内部类

Question

Elasticsearch/Spark序列化似乎不适合嵌套类型.

例如:

public class Foo implements Serializable {
   private List<Bar> bars = new ArrayList<Bar>();
   // getters and setters

   public static class Bar implements Serializable {
   }
}

List<Foo> foos = new ArrayList<Foo>();
foos.add( new Foo());
// Note: Foo object does not contain nested Bar instances

SparkConf sc = new SparkConf(); //
sc.setMaster("local");
sc.setAppName("spark.app.name");
sc.set("spark.serializer", KryoSerializer.class.getName()); 
JavaSparkContext jsc = new JavaSparkContext(sc);
JavaRDD javaRDD = jsc.parallelize(ImmutableList.copyOf(foos));
JavaEsSpark.saveToEs(javaRDD, INDEX_NAME+"/"+TYPE_NAME);  

上面的代码可以工作,类型文档Foo将在Elasticsearch中编入索引.

当对象中的bars列表Foo不为空时,会出现问题,例如:

Foo = new Foo();
Bar = new Foo.Bar();
foo.getBars().add(bar);

然后,在索引到Elasticsearch时,会抛出以下异常:

org.elasticsearch.hadoop.serialization.EsHadoopSerializationException: 
Cannot handle type [Bar] within type [class Foo], instance [Bar ...]] 
within instance [Foo@1cf628a] 
using writer [org.elasticsearch.spark.serialization.ScalaValueWriter@4e635d]
at org.elasticsearch.hadoop.serialization.builder.ContentBuilder.value(ContentBuilder.java:63)
at org.elasticsearch.hadoop.serialization.bulk.TemplatedBulk.doWriteObject(TemplatedBulk.java:71)
at org.elasticsearch.hadoop.serialization.bulk.TemplatedBulk.write(TemplatedBulk.java:58)
at org.elasticsearch.hadoop.rest.RestRepository.writeToIndex(RestRepository.java:148)
at org.elasticsearch.spark.rdd.EsRDDWriter.write(EsRDDWriter.scala:47)
at org.elasticsearch.spark.rdd.EsSpark$$anonfun$saveToEs$1.apply(EsSpark.scala:68)
at org.elasticsearch.spark.rdd.EsSpark$$anonfun$saveToEs$1.apply(EsSpark.scala:68)
at org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:61)
at org.apache.spark.scheduler.Task.run(Task.scala:64)
at org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:203)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)

这些是相关的Maven依赖项

<dependency>
   <groupId>com.sksamuel.elastic4s</groupId>
   <artifactId>elastic4s_2.11</artifactId>
   <version>1.5.5</version>
</dependency>

<dependency>
   <groupId>org.apache.spark</groupId>
   <artifactId>spark-core_2.11</artifactId>
   <version>1.3.1</version>
</dependency>

<dependency>
   <groupId>org.elasticsearch</groupId>
   <artifactId>elasticsearch-hadoop-cascading</artifactId>
   <version>2.1.0.Beta4</version>
</dependency>

<dependency>
   <groupId>com.fasterxml.jackson.core</groupId>
   <artifactId>jackson-databind</artifactId>
   <version>2.1.3</version>
</dependency>

<dependency>
   <groupId>org.elasticsearch</groupId>
   <artifactId>elasticsearch-spark_2.10</artifactId>
   <version>2.1.0.Beta4</version>
</dependency>

<dependency>
   <groupId>org.scala-lang</groupId>
   <artifactId>scala-xml</artifactId>
   <version>2.11.0-M4</version>
</dependency>

在ElasticSearch和Spark中使用嵌套类型时索引的正确方法是什么？

谢谢

Answer 1

查看 ScalaValueWriter 和 JdkValueWriter 代码，我们可以看到仅直接支持某些类型。内部类很可能不是 JavaBean 或其他受支持的类型。