Question

我目前正在使用Apache Cassandra（Cassandra版本：1.2.3，Thrift API版本：19.35.0，CQL支持版本：2.0.0,3.0.1（默认值：3.0.1））和Hector 1.0.5。

我使用以下代码插入和检索对象。

String cf="User";
key="myKey";
String colName="colName";
String colValue="colvalue";

Mutator<String> mutator = HFactory.createMutator(keyspace, StringSerializer.get());
mutator.insert(key, cf, HFactory.createStringColumn(colName, colValue));



ColumnQuery<String, String, Object> columnQuery = HFactory.createColumnQuery(
    keyspace,
    StringSerializer.get(),
    StringSerializer.get(),
    ObjectSerializer.get());

    columnQuery.setColumnFamily(cf).setKey(key).setName(colName);
    QueryResult<HColumn<String, Object>> r = columnQuery.execute();

    System.out.println("Read HColumn from cassandra: " + r.get());

但我得到以下例外：

Exception in thread "main" me.prettyprint.hector.api.exceptions.HectorSerializationException: java.io.StreamCorruptedException: invalid stream header: 636F6C76
    at me.prettyprint.cassandra.serializers.ObjectSerializer.fromByteBuffer(ObjectSerializer.java:79)
    at me.prettyprint.cassandra.model.HColumnImpl.getValue(HColumnImpl.java:124)
    at me.prettyprint.cassandra.model.HColumnImpl.toString(HColumnImpl.java:202)
    at java.lang.String.valueOf(String.java:2854)
    at java.lang.StringBuilder.append(StringBuilder.java:128)
    at org.dargamenteria.tfg.texu.logic.UserDAOImpl.create(UserDAOImpl.java:111)

但是下面的代码可以工作，只是将ObjectSerializer更改为StringSerializer：

Mutator<String> mutator = HFactory.createMutator(keyspace, StringSerializer.get());
mutator.insert(key, cf, HFactory.createStringColumn(colName, colValue));

ColumnQuery<String, String, String> columnQuery = HFactory.createColumnQuery(
    keyspace,
    StringSerializer.get(),
    StringSerializer.get(),
    StringSerializer.get());

    columnQuery.setColumnFamily(cf).setKey(key).setName(colName);
    QueryResult<HColumn<String, String>> r = columnQuery.execute();

    System.out.println("Read HColumn from cassandra: " + r.get());

Answer 1

如果您查看Hector Serializer层次结构，您会发现ObjectSerializer＆amp; StringSerializer都是兄弟姐妹，都实现了Serializer接口和扩展AbstractSerializer类。

StringSerializer中的

fromByteBuffer 方法需要一个字符串，而在ObjectSerializer中它需要一个对象。在您的代码中，您已将列值定义为字符串类型，因此您必须使用StringSerializer，因为您的代码集期望String类型。

Answer 2

首先，感谢Abhi的回答:)你提供了一些重要的线索。

我所做的是使用正确的序列化器插入ByteBuffers。例如

mutator.addInsertion(key, columnFamilyName, 
HFactory.createColumn("name",                   
    ByteBufferSerializer.get().fromByteBuffer(StringSerializer.get().toByteBuffer(uh.getName())), 
    StringSerializer.get(),
    ByteBufferSerializer.get())).

addInsertion(key, columnFamilyName, 
HFactory.createColumn("email",                  
    ByteBufferSerializer.get().fromByteBuffer(ObjectSerializer.get().toByteBuffer(uh.getEmail())), 
    StringSerializer.get(),
    ByteBufferSerializer.get())).

并检索它们，例如

 StringSerializer.get().fromByteBuffer(
                r.get().getColumnByName("name").getValue())

谢谢大家！

Cassandra：Hector，serializationException无效的stram头

2 个答案: