[120] | 1 | /** |
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| 2 | * Licensed to the Apache Software Foundation (ASF) under one |
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| 3 | * or more contributor license agreements. See the NOTICE file |
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| 4 | * distributed with this work for additional information |
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| 5 | * regarding copyright ownership. The ASF licenses this file |
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| 6 | * to you under the Apache License, Version 2.0 (the |
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| 7 | * "License"); you may not use this file except in compliance |
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| 8 | * with the License. You may obtain a copy of the License at |
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| 9 | * |
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| 10 | * http://www.apache.org/licenses/LICENSE-2.0 |
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| 11 | * |
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| 12 | * Unless required by applicable law or agreed to in writing, software |
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| 13 | * distributed under the License is distributed on an "AS IS" BASIS, |
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| 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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| 15 | * See the License for the specific language governing permissions and |
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| 16 | * limitations under the License. |
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| 17 | */ |
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| 18 | |
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| 19 | package org.apache.hadoop.io; |
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| 20 | |
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| 21 | import org.apache.hadoop.conf.*; |
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| 22 | import org.apache.hadoop.util.ReflectionUtils; |
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| 23 | import java.util.HashMap; |
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| 24 | |
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| 25 | /** Factories for non-public writables. Defining a factory permits {@link |
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| 26 | * ObjectWritable} to be able to construct instances of non-public classes. */ |
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| 27 | public class WritableFactories { |
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| 28 | private static final HashMap<Class, WritableFactory> CLASS_TO_FACTORY = |
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| 29 | new HashMap<Class, WritableFactory>(); |
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| 30 | |
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| 31 | private WritableFactories() {} // singleton |
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| 32 | |
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| 33 | /** Define a factory for a class. */ |
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| 34 | public static synchronized void setFactory(Class c, WritableFactory factory) { |
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| 35 | CLASS_TO_FACTORY.put(c, factory); |
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| 36 | } |
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| 37 | |
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| 38 | /** Define a factory for a class. */ |
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| 39 | public static synchronized WritableFactory getFactory(Class c) { |
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| 40 | return CLASS_TO_FACTORY.get(c); |
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| 41 | } |
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| 42 | |
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| 43 | /** Create a new instance of a class with a defined factory. */ |
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| 44 | public static Writable newInstance(Class<? extends Writable> c, Configuration conf) { |
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| 45 | WritableFactory factory = WritableFactories.getFactory(c); |
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| 46 | if (factory != null) { |
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| 47 | Writable result = factory.newInstance(); |
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| 48 | if (result instanceof Configurable) { |
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| 49 | ((Configurable) result).setConf(conf); |
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| 50 | } |
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| 51 | return result; |
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| 52 | } else { |
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| 53 | return ReflectionUtils.newInstance(c, conf); |
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| 54 | } |
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| 55 | } |
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| 56 | |
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| 57 | /** Create a new instance of a class with a defined factory. */ |
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| 58 | public static Writable newInstance(Class<? extends Writable> c) { |
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| 59 | return newInstance(c, null); |
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| 60 | } |
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| 61 | |
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| 62 | } |
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| 63 | |
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