读取列/列列表（Scala）时的 Astyanax / Cassandra InstantiationException答案

【问题标题】：Astyanax / Cassandra InstantiationException when reading column / columnlist (Scala)读取列/列列表（Scala）时的 Astyanax / Cassandra InstantiationException
【发布时间】：2012-09-04 00:09:36
【问题描述】：

在这个问题上坚持了几个小时！非常感谢您的任何见解:)

Scala 2.9.2
Astyanax 1.0.6（也尝试过 1.0.5）
卡桑德拉 1.1.4
使用 CompositeRowKey、CompositeColumnName
插入 Cassandra 没问题
可以读取一行，ColumnList.size() 返回正确的计数，但是任何访问 ColumnList 的尝试（即迭代、访问迭代 ColumnList、getColumnByIndex()、getColumnByName() 等）都会引发以下异常：

例外：

java.lang.RuntimeException: java.lang.InstantiationException

相关堆栈跟踪：

java.lang.RuntimeException: java.lang.InstantiationException: shops.integration.db.scalaquery.ReportingDao$MetricsLogFileCompositeColumn
        at com.netflix.astyanax.serializers.AnnotatedCompositeSerializer.fromByteBuffer(AnnotatedCompositeSerializer.java:136)
        at com.netflix.astyanax.serializers.AbstractSerializer.fromBytes(AbstractSerializer.java:40)
        at com.netflix.astyanax.thrift.model.ThriftColumnOrSuperColumnListImpl.constructMap(ThriftColumnOrSuperColumnListImpl.java:201)
        at com.netflix.astyanax.thrift.model.ThriftColumnOrSuperColumnListImpl.getColumn(ThriftColumnOrSuperColumnListImpl.java:189)
        at com.netflix.astyanax.thrift.model.ThriftColumnOrSuperColumnListImpl.getColumnByName(ThriftColumnOrSuperColumnListImpl.java:103)

具体来说：

at java.lang.Class.newInstance0(Class.java:357)
at java.lang.Class.newInstance(Class.java:325)
at com.netflix.astyanax.serializers.AnnotatedCompositeSerializer.createContents(AnnotatedCompositeSerializer.java:167)

相关示例代码：

class TestCompositeColumn(@(Component @field) var logFileId: Long, @(Component @field) var dt: String, @(Component @field) var dk: String) extends Ordered[TestCompositeColumn] {
    def this() = this(0l, "", "")
    //equals, hashCode, compare all implemented
}

我也在课堂上尝试过这种变体：

class TestCompositeColumn(idIn: Long, key1In: String, key2In: String) extends Ordered[TestCompositeColumn] {
    @Component(ordinal = 0) var id: Long = idIn
    @Component(ordinal = 1) var key1: String = key1In
    @Component(ordinal = 2) var key2: String = key2In

    def this() = this(0, null, null)
    //equals, hashCode, compare all implemented
}

val TEST_COLUMN_FAMILY = new ColumnFamily[TestRowKey, TestCompositeColumn](
    "test_column_family",
    new AnnotatedCompositeSerializer[TestRowKey](classOf[TestRowKey]),
    new AnnotatedCompositeSerializer[TestCompositeColumn](classOf[TestCompositeColumn]),
    BytesArraySerializer.get());

var columnList = keyspace.prepareQuery(TEST_COLUMN_FAMILY)
    .getKey(TestRowKey(1l, 2012090100))
    .execute().getResult()

    // OK - will return 6 for example, also verified via cassandra-cli
    println(columnList.size())         

    // ERROR - will throw exception above.  Iterating, or any type of access will also throw same exception
    println(columnList.getColumnByIndex(0).getStringValue())

【问题讨论】：

标签： scala cassandra astyanax

【解决方案1】：

原来TestCompositeColumn不能定义为内部类。

【讨论】：