org.apache.hadoop.hive.serde2.AbstractSerDe Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.hive.serde2;
import java.util.Properties;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.io.Writable;
/**
* Abstract class for implementing SerDe. The abstract class has been created, so that
* new methods can be added in the underlying interface, SerDe, and only implementations
* that need those methods overwrite it.
*/
public abstract class AbstractSerDe implements SerDe {
/**
* Initialize the HiveSerializer.
*
* @param conf
* System properties
* @param tbl
* table properties
* @throws SerDeException
*/
public abstract void initialize(Configuration conf, Properties tbl) throws SerDeException;
/**
* Returns the Writable class that would be returned by the serialize method.
* This is used to initialize SequenceFile header.
*/
public abstract Class getSerializedClass();
/**
* Serialize an object by navigating inside the Object with the
* ObjectInspector. In most cases, the return value of this function will be
* constant since the function will reuse the Writable object. If the client
* wants to keep a copy of the Writable, the client needs to clone the
* returned value.
*/
public abstract Writable serialize(Object obj, ObjectInspector objInspector)
throws SerDeException;
/**
* Returns statistics collected when serializing
*/
public abstract SerDeStats getSerDeStats();
/**
* Deserialize an object out of a Writable blob. In most cases, the return
* value of this function will be constant since the function will reuse the
* returned object. If the client wants to keep a copy of the object, the
* client needs to clone the returned value by calling
* ObjectInspectorUtils.getStandardObject().
*
* @param blob
* The Writable object containing a serialized object
* @return A Java object representing the contents in the blob.
*/
public abstract Object deserialize(Writable blob) throws SerDeException;
/**
* Get the object inspector that can be used to navigate through the internal
* structure of the Object returned from deserialize(...).
*/
public abstract ObjectInspector getObjectInspector() throws SerDeException;
}