Add Spring BeanPostProcessor to initialize an Apache Geode Region (bean) with data on Spring container initialization.

spring-data-geode-test/src/main/java/org/springframework/data/gemfire/tests/objects/geode/cache/RegionDataInitializingPostProcessor.java

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+/*
+ *  Copyright 2019 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
+ *
+ *       https://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.data.gemfire.tests.objects.geode.cache;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Function;
+
+import org.apache.geode.cache.Region;
+
+import org.springframework.beans.BeansException;
+import org.springframework.beans.factory.config.BeanPostProcessor;
+import org.springframework.lang.NonNull;
+import org.springframework.util.Assert;
+
+/**
+ * Spring {@link BeanPostProcessor} used to initialize an Apache Geode {@link Region} with data.
+ *
+ * @author John Blum
+ * @see java.util.Map
+ * @see java.util.function.Function
+ * @see org.apache.geode.cache.Region
+ * @see org.springframework.beans.factory.config.BeanPostProcessor
+ * @since 0.0.26
+ */
+@SuppressWarnings("unused")
+public class RegionDataInitializingPostProcessor<T> implements BeanPostProcessor {
+
+	public static <T> EntityIdentifierBuilder<T> withRegion(@NonNull String regionBeanName) {
+		return new EntityIdentifierBuilder<>(new RegionDataInitializingPostProcessor<>(regionBeanName));
+	}
+
+	private Function<T, Object> entityIdentifierFunction;
+
+	private final Map<Object, T> regionData = new ConcurrentHashMap<>();
+
+	private final String regionBeanName;
+
+	protected RegionDataInitializingPostProcessor(@NonNull String regionBeanName) {
+
+		Assert.hasText(regionBeanName, String.format("Region bean name [%s] must be specified", regionBeanName));
+
+		this.regionBeanName = regionBeanName;
+	}
+
+	public @NonNull String getRegionBeanName() {
+		return this.regionBeanName;
+	}
+
+	protected @NonNull Function<T, Object> getEntityIdentifierFunction() {
+		return this.entityIdentifierFunction;
+	}
+
+	public @NonNull Map<Object, T> getRegionData() {
+		return this.regionData;
+	}
+
+	protected boolean isTargetRegion(Object bean, String beanName) {
+		return bean instanceof Region && getRegionBeanName().equals(beanName);
+	}
+
+	@Override
+	@SuppressWarnings("unchecked")
+	public Object postProcessAfterInitialization(@NonNull Object bean, @NonNull String beanName) throws BeansException {
+
+		if (isTargetRegion(bean, beanName)) {
+			((Region<Object, T>) bean).putAll(getRegionData());
+		}
+
+		return bean;
+	}
+
+	public RegionDataInitializingPostProcessor<T> store(T entity) {
+		getRegionData().put(getEntityIdentifierFunction().apply(entity), entity);
+		return this;
+	}
+
+	protected RegionDataInitializingPostProcessor<T> useEntityIdentifierFunction(
+		@NonNull Function<T, Object> entityIdentifierFunction) {
+
+		Assert.notNull(entityIdentifierFunction,
+			"The Function used to resolve the entity's identify (identifier) must not be null");
+
+		this.entityIdentifierFunction = entityIdentifierFunction;
+
+		return this;
+	}
+
+	@SuppressWarnings("unused")
+	public static class EntityIdentifierBuilder<T> {
+
+		private final RegionDataInitializingPostProcessor<T> postProcessor;
+
+		private EntityIdentifierBuilder(@NonNull RegionDataInitializingPostProcessor<T> postProcessor) {
+			Assert.notNull(postProcessor, "RegionDataInitializingPostProcess must not be null");
+			this.postProcessor = postProcessor;
+		}
+
+		public RegionDataInitializingPostProcessor<T> useAsEntityIdentifier(
+				@NonNull Function<T, Object> entityIdentifierFunction) {
+
+			return this.postProcessor.useEntityIdentifierFunction(entityIdentifierFunction);
+		}
+	}
+}