/*
* Copyright 2014-2014 Amazon Technologies, Inc.
*
* Licensed 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://aws.amazon.com/apache2.0
*
* This file 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 com.amazonaws.services.dynamodbv2.datamodeling.unmarshallers;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMappingException;
import com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMarshaller;
import com.amazonaws.services.dynamodbv2.model.AttributeValue;
/**
* An unmarshaller that delegates to an instance of a
* {@code DynamoDBMarshaller}-derived custom marshaler.
*/
public class CustomUnmarshaller extends SUnmarshaller {
private final Class<?> targetClass;
private final Class<? extends DynamoDBMarshaller<?>> unmarshallerClass;
public CustomUnmarshaller(
Class<?> targetClass,
Class<? extends DynamoDBMarshaller<?>> unmarshallerClass) {
this.targetClass = targetClass;
this.unmarshallerClass = unmarshallerClass;
}
@Override
@SuppressWarnings({ "rawtypes", "unchecked" })
public Object unmarshall(AttributeValue value) {
// TODO: Would be nice to cache this object, but not sure if we can
// do that now without a breaking change; user's unmarshallers
// might not all be thread-safe.
DynamoDBMarshaller unmarshaller =
createUnmarshaller(unmarshallerClass);
return unmarshaller.unmarshall(targetClass, value.getS());
}
@SuppressWarnings({ "rawtypes" })
private static DynamoDBMarshaller createUnmarshaller(Class<?> clazz) {
try {
return (DynamoDBMarshaller) clazz.newInstance();
} catch (InstantiationException e) {
throw new DynamoDBMappingException(
"Failed to instantiate custom marshaler for class " + clazz,
e);
} catch (IllegalAccessException e) {
throw new DynamoDBMappingException(
"Failed to instantiate custom marshaler for class " + clazz,
e);
}
}
}