add ClassifierCompositeItemProcessor

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/support/ClassifierCompositeItemProcessor.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2014 the original author or authors.
+ *
+ * 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://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.springframework.batch.item.support;
+
+import org.springframework.batch.item.ItemProcessor;
+import org.springframework.classify.Classifier;
+import org.springframework.classify.ClassifierSupport;
+
+/**
+ * Calls one of a collection of ItemProcessors, based on a router
+ * pattern implemented through the provided {@link Classifier}.
+ * 
+ * Note the user is responsible for injecting a {@link Classifier}
+ * that returns an ItemProcessor that conforms to the declared input and output types.
+ * 
+ * @author Jimmy Praet
+ * @since 3.0
+ */
+public class ClassifierCompositeItemProcessor<I,O> implements ItemProcessor<I, O> {
+
+	private Classifier<? super I, ItemProcessor<?, ? extends O>> classifier = 
+			new ClassifierSupport<I, ItemProcessor<?, ? extends O>> (null);
+
+	/**
+	 * @param classifier the classifier to set
+	 */
+	public void setClassifier(Classifier<? super I, ItemProcessor<?, ? extends O>> classifier) {
+		this.classifier = classifier;
+	}
+	
+	/**
+	 * Delegates to injected {@link ItemProcessor} instances according to the
+	 * classification by the {@link Classifier}.
+	 */
+	@Override
+	public O process(I item) throws Exception {
+		return processItem(classifier.classify(item), item);
+	}
+	
+    /* 
+     * Helper method to work around wildcard capture compiler error: see http://docs.oracle.com/javase/tutorial/java/generics/capture.html
+     * The method process(capture#4-of ?) in the type ItemProcessor<capture#4-of ?,capture#5-of ? extends O> is not applicable for the arguments (I)
+     */
+    @SuppressWarnings("unchecked")
+	private <T> O processItem(ItemProcessor<T, ? extends O> processor, I input) throws Exception {
+    	return processor.process((T) input);
+    }	
+
+}