| 1 | /* |
| 2 | * Copyright 2006-2007 the original author or authors. |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | package org.springframework.batch.classify; |
| 17 | |
| 18 | import org.springframework.batch.support.MethodInvoker; |
| 19 | import org.springframework.batch.support.MethodInvokerUtils; |
| 20 | import org.springframework.util.Assert; |
| 21 | |
| 22 | /** |
| 23 | * Wrapper for an object to adapt it to the {@link Classifier} interface. |
| 24 | * |
| 25 | * @author Dave Syer |
| 26 | * |
| 27 | */ |
| 28 | public class ClassifierAdapter<C, T> implements Classifier<C, T> { |
| 29 | |
| 30 | private MethodInvoker invoker; |
| 31 | |
| 32 | private Classifier<C, T> classifier; |
| 33 | |
| 34 | /** |
| 35 | * Default constructor for use with setter injection. |
| 36 | */ |
| 37 | public ClassifierAdapter() { |
| 38 | super(); |
| 39 | } |
| 40 | |
| 41 | /** |
| 42 | * Create a new {@link Classifier} from the delegate provided. Use the |
| 43 | * constructor as an alternative to the {@link #setDelegate(Object)} method. |
| 44 | * |
| 45 | * @param delegate |
| 46 | */ |
| 47 | public ClassifierAdapter(Object delegate) { |
| 48 | setDelegate(delegate); |
| 49 | } |
| 50 | |
| 51 | /** |
| 52 | * Create a new {@link Classifier} from the delegate provided. Use the |
| 53 | * constructor as an alternative to the {@link #setDelegate(Classifier)} |
| 54 | * method. |
| 55 | * |
| 56 | * @param delegate |
| 57 | */ |
| 58 | public ClassifierAdapter(Classifier<C, T> delegate) { |
| 59 | classifier = delegate; |
| 60 | } |
| 61 | |
| 62 | public void setDelegate(Classifier<C, T> delegate) { |
| 63 | classifier = delegate; |
| 64 | invoker = null; |
| 65 | } |
| 66 | |
| 67 | /** |
| 68 | * Search for the |
| 69 | * {@link org.springframework.batch.support.annotation.Classifier |
| 70 | * Classifier} annotation on a method in the supplied delegate and use that |
| 71 | * to create a {@link Classifier} from the parameter type to the return |
| 72 | * type. If the annotation is not found a unique non-void method with a |
| 73 | * single parameter will be used, if it exists. The signature of the method |
| 74 | * cannot be checked here, so might be a runtime exception when the method |
| 75 | * is invoked if the signature doesn't match the classifier types. |
| 76 | * |
| 77 | * @param delegate an object with an annotated method |
| 78 | */ |
| 79 | public final void setDelegate(Object delegate) { |
| 80 | classifier = null; |
| 81 | invoker = MethodInvokerUtils.getMethodInvokerByAnnotation( |
| 82 | org.springframework.batch.support.annotation.Classifier.class, delegate); |
| 83 | if (invoker == null) { |
| 84 | invoker = MethodInvokerUtils.<C, T> getMethodInvokerForSingleArgument(delegate); |
| 85 | } |
| 86 | Assert.state(invoker != null, "No single argument public method with or without " |
| 87 | + "@Classifier was found in delegate of type " + delegate.getClass()); |
| 88 | } |
| 89 | |
| 90 | /** |
| 91 | * {@inheritDoc} |
| 92 | */ |
| 93 | @SuppressWarnings("unchecked") |
| 94 | public T classify(C classifiable) { |
| 95 | if (classifier != null) { |
| 96 | return classifier.classify(classifiable); |
| 97 | } |
| 98 | return (T) invoker.invokeMethod(classifiable); |
| 99 | } |
| 100 | |
| 101 | } |