Added builder for MongoItemReader

resolves BATCH-2612

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/data/builder/MongoItemReaderBuilder.java

@@ -0,0 +1,211 @@
+/*
+ * Copyright 2017 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.data.builder;
+
+import java.util.List;
+import java.util.Map;
+
+import org.springframework.batch.item.builder.AbstractItemCountingItemStreamItemReaderBuilder;
+import org.springframework.batch.item.data.MongoItemReader;
+import org.springframework.data.domain.Sort;
+import org.springframework.data.mongodb.core.MongoOperations;
+import org.springframework.util.Assert;
+
+/**
+ * A builder implementation for the {@link MongoItemReader}
+ *
+ * @author Glenn Renfro
+ * @since 4.0
+ * @see MongoItemReader
+ */
+public class MongoItemReaderBuilder<T>
+		extends AbstractItemCountingItemStreamItemReaderBuilder<MongoItemReaderBuilder<T>> {
+	private MongoOperations template;
+
+	private String query;
+
+	private Class<? extends T> targetType;
+
+	Map<String, Sort.Direction> sorts;
+
+	private String hint;
+
+	private String fields;
+
+	private String collection;
+
+	private List<Object> parameterValues;
+
+	protected int pageSize = 10;
+
+	/**
+	 * Used to perform operations against the MongoDB instance. Also handles the mapping
+	 * of documents to objects.
+	 *
+	 * @param template the MongoOperations instance to use
+	 * @see MongoOperations
+	 * @return The current instance of the builder
+	 * @see MongoItemReader#setTemplate(MongoOperations)
+	 */
+	public MongoItemReaderBuilder<T> template(MongoOperations template) {
+		this.template = template;
+
+		return this;
+	}
+
+	/**
+	 * A JSON formatted MongoDB query. Parameterization of the provided query is allowed
+	 * via ?&lt;index&gt; placeholders where the &lt;index&gt; indicates the index of the
+	 * parameterValue to substitute.
+	 *
+	 * @param query JSON formatted Mongo query
+	 * @return The current instance of the builder
+	 * @see MongoItemReader#setQuery(String)
+	 */
+	public MongoItemReaderBuilder<T> query(String query) {
+		this.query = query;
+
+		return this;
+	}
+
+	/**
+	 * The type of object to be returned for each {@link MongoItemReader#read()} call.
+	 *
+	 * @param targetType the type of object to return
+	 * @return The current instance of the builder
+	 * @see MongoItemReader#setTargetType(Class)
+	 */
+	public MongoItemReaderBuilder<T> targetType(Class<? extends T> targetType) {
+		this.targetType = targetType;
+
+		return this;
+	}
+
+	/**
+	 * {@link List} of values to be substituted in for each of the parameters in the
+	 * query.
+	 *
+	 * @param parameterValues values
+	 * @return The current instance of the builder
+	 * @see MongoItemReader#setParameterValues(List)
+	 */
+	public MongoItemReaderBuilder<T> parameterValues(List<Object> parameterValues) {
+		this.parameterValues = parameterValues;
+
+		return this;
+	}
+
+	/**
+	 * JSON defining the fields to be returned from the matching documents by MongoDB.
+	 *
+	 * @param fields JSON string that identifies the fields to sort by.
+	 * @return The current instance of the builder
+	 * @see MongoItemReader#setFields(String)
+	 */
+	public MongoItemReaderBuilder<T> fields(String fields) {
+		this.fields = fields;
+
+		return this;
+	}
+
+	/**
+	 * {@link Map} of property
+	 * names/{@link org.springframework.data.domain.Sort.Direction} values to sort the
+	 * input by.
+	 *
+	 * @param sorts map of properties and direction to sort each.
+	 * @return The current instance of the builder
+	 * @see MongoItemReader#setSort(Map)
+	 */
+	public MongoItemReaderBuilder<T> sorts(Map<String, Sort.Direction> sorts) {
+		this.sorts = sorts;
+
+		return this;
+	}
+
+	/**
+	 * Establish an optional collection that can be queried.
+	 *
+	 * @param collection Mongo collection to be queried.
+	 * @return The current instance of the builder
+	 * @see MongoItemReader#setCollection(String)
+	 */
+	public MongoItemReaderBuilder<T> collection(String collection) {
+		this.collection = collection;
+
+		return this;
+	}
+
+	/**
+	 * JSON String telling MongoDB what index to use.
+	 *
+	 * @param hint string indicating what index to use.
+	 * @return The current instance of the builder
+	 * @see MongoItemReader#setHint(String)
+	 */
+	public MongoItemReaderBuilder<T> hint(String hint) {
+		this.hint = hint;
+
+		return this;
+	}
+
+	/**
+	 * The number of items to be read with each page.
+	 *
+	 * @param pageSize the number of items
+	 * @return this instance for method chaining
+	 * @see MongoItemReader#setPageSize(int)
+	 */
+	public MongoItemReaderBuilder<T> pageSize(int pageSize) {
+		this.pageSize = pageSize;
+
+		return this;
+	}
+
+	/**
+	 * Validates and builds a {@link MongoItemReader}.
+	 *
+	 * @return a {@link MongoItemReader}
+	 */
+	public MongoItemReader<T> build() {
+		Assert.notNull(this.template, "template is required.");
+		if (this.saveState) {
+			Assert.hasText(this.name, "A name is required when saveState is set to true");
+		}
+		Assert.notNull(this.targetType, "targetType is required.");
+		Assert.notNull(this.query, "query is required.");
+		Assert.notNull(this.sorts, "sorts map is required.");
+
+		MongoItemReader<T> reader = new MongoItemReader<>();
+		reader.setTemplate(this.template);
+		reader.setTargetType(this.targetType);
+		reader.setQuery(this.query);
+		reader.setSort(this.sorts);
+		reader.setHint(this.hint);
+		reader.setFields(this.fields);
+		reader.setCollection(this.collection);
+		reader.setParameterValues(this.parameterValues);
+
+		reader.setPageSize(this.pageSize);
+		reader.setName(this.name);
+		reader.setSaveState(this.saveState);
+		reader.setCurrentItemCount(this.currentItemCount);
+		reader.setMaxItemCount(this.maxItemCount);
+
+		return reader;
+	}
+}