Added a builder for JdbcBatchItemWriter

This commit adds a builder for the JdbcBatchItemWriter that includes a
couple nicities to simplify configuration of basic use cases.

Resolves BATCH-2561

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/database/builder/JdbcBatchItemWriterBuilder.java

@@ -0,0 +1,199 @@
+/*
+ * Copyright 2016 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.database.builder;
+
+import java.math.BigInteger;
+import java.util.Map;
+import javax.sql.DataSource;
+
+import org.springframework.batch.item.database.BeanPropertyItemSqlParameterSourceProvider;
+import org.springframework.batch.item.database.ItemPreparedStatementSetter;
+import org.springframework.batch.item.database.ItemSqlParameterSourceProvider;
+import org.springframework.batch.item.database.JdbcBatchItemWriter;
+import org.springframework.batch.item.database.support.ColumnMapItemPreparedStatementSetter;
+import org.springframework.jdbc.core.namedparam.NamedParameterJdbcOperations;
+import org.springframework.jdbc.core.namedparam.NamedParameterJdbcTemplate;
+import org.springframework.util.Assert;
+
+/**
+ * A builder implementation for the {@link JdbcBatchItemWriter}.
+ *
+ * @author Michael Minella
+ * @since 4.0
+ * @see JdbcBatchItemWriter
+ */
+public class JdbcBatchItemWriterBuilder<T> {
+
+	private boolean assertUpdates = true;
+
+	private String sql;
+
+	private ItemPreparedStatementSetter<T> itemPreparedStatementSetter;
+
+	private ItemSqlParameterSourceProvider<T> itemSqlParameterSourceProvider;
+
+	private DataSource dataSource;
+
+	private NamedParameterJdbcOperations namedParameterJdbcTemplate;
+
+	private BigInteger mapped = new BigInteger("0");
+
+	/**
+	 * Configure the {@link DataSource} to be used.
+	 *
+	 * @param dataSource the DataSource
+	 * @return The current instance of the builder for chaining.
+	 * @see JdbcBatchItemWriter#setDataSource(DataSource)
+	 */
+	public JdbcBatchItemWriterBuilder<T> dataSource(DataSource dataSource) {
+		this.dataSource = dataSource;
+
+		return this;
+	}
+
+	/**
+	 * If set to true, confirms that every insert results in the update of at least one
+	 * row in the database.  Defaults to true.
+	 *
+	 * @param assertUpdates boolean indicator
+	 * @return The current instance of the builder for chaining
+	 * @see JdbcBatchItemWriter#setAssertUpdates(boolean)
+	 */
+	public JdbcBatchItemWriterBuilder<T> assertUpdates(boolean assertUpdates) {
+		this.assertUpdates = assertUpdates;
+
+		return this;
+	}
+
+	/**
+	 * Set the SQL statement to be used for each item's updates.  This is a required
+	 * field.
+	 *
+	 * @param sql SQL string
+	 * @return The current instance of the builder for chaining
+	 * @see JdbcBatchItemWriter#setSql(String)
+	 */
+	public JdbcBatchItemWriterBuilder<T> sql(String sql) {
+		this.sql = sql;
+
+		return this;
+	}
+
+	/**
+	 * Configures a {@link ItemPreparedStatementSetter} for use by the writer.  This
+	 * should only be used if {@link #columnMapped()} isn't called.
+	 *
+	 * @param itemPreparedStatementSetter The {@link ItemPreparedStatementSetter}
+	 * @return The current instance of the builder for chaining
+	 * @see JdbcBatchItemWriter#setItemPreparedStatementSetter(ItemPreparedStatementSetter)
+	 */
+	public JdbcBatchItemWriterBuilder<T> itemPreparedStatementSetter(ItemPreparedStatementSetter<T> itemPreparedStatementSetter) {
+		this.itemPreparedStatementSetter = itemPreparedStatementSetter;
+
+		return this;
+	}
+
+	/**
+	 * Configures a {@link ItemSqlParameterSourceProvider} for use by the writer.  This
+	 * should only be used if {@link #beanMapped()} isn't called.
+	 *
+	 * @param itemSqlParameterSourceProvider The {@link ItemSqlParameterSourceProvider}
+	 * @return The current instance of the builder for chaining
+	 * @see JdbcBatchItemWriter#setItemSqlParameterSourceProvider(ItemSqlParameterSourceProvider)
+	 */
+	public JdbcBatchItemWriterBuilder<T> itemSqlParameterSourceProvider(ItemSqlParameterSourceProvider<T> itemSqlParameterSourceProvider) {
+		this.itemSqlParameterSourceProvider = itemSqlParameterSourceProvider;
+
+		return this;
+	}
+
+	/**
+	 * The {@link NamedParameterJdbcOperations} instance to use.  If one isn't provided,
+	 * a {@link DataSource} is required.
+	 *
+	 * @param namedParameterJdbcOperations The template
+	 * @return The current instance of the builder for chaining
+	 */
+	public JdbcBatchItemWriterBuilder<T> namedParametersJdbcTemplate(NamedParameterJdbcOperations namedParameterJdbcOperations) {
+		this.namedParameterJdbcTemplate = namedParameterJdbcOperations;
+
+		return this;
+	}
+
+	/**
+	 * Creates a {@link ColumnMapItemPreparedStatementSetter} to be used as your
+	 * {@link ItemPreparedStatementSetter}.
+	 *
+	 * NOTE: The item type for this {@link org.springframework.batch.item.ItemWriter} must
+	 * be castable to <code>Map&lt;String,Object&gt;&gt;</code>.
+	 *
+	 * @return The current instance of the builder for chaining
+	 * @see ColumnMapItemPreparedStatementSetter
+	 */
+	public JdbcBatchItemWriterBuilder<T> columnMapped() {
+		this.mapped = this.mapped.setBit(0);
+
+		return this;
+	}
+
+	/**
+	 * Creates a {@link BeanPropertyItemSqlParameterSourceProvider} to be used as your
+	 * {@link ItemSqlParameterSourceProvider}.
+	 *
+	 * @return The current instance of the builder for chaining
+	 * @see BeanPropertyItemSqlParameterSourceProvider
+	 */
+	public JdbcBatchItemWriterBuilder<T> beanMapped() {
+		this.mapped = this.mapped.setBit(1);
+
+		return this;
+	}
+
+	/**
+	 * Validates configuration and builds the {@link JdbcBatchItemWriter}.
+	 *
+	 * @return a {@link JdbcBatchItemWriter}
+	 */
+	public JdbcBatchItemWriter<T> build() {
+		Assert.state(this.dataSource != null || this.namedParameterJdbcTemplate != null,
+				"Either a DataSource or a NamedParameterJdbcTemplate is required");
+
+		Assert.notNull(this.sql, "A SQL statement is required");
+		int mappedValue = this.mapped.intValue();
+		Assert.state(mappedValue != 3,
+				"Either an item can be mapped via db column or via bean spec, can't be both");
+
+		JdbcBatchItemWriter<T> writer = new JdbcBatchItemWriter<>();
+		writer.setSql(this.sql);
+		writer.setAssertUpdates(this.assertUpdates);
+		writer.setItemSqlParameterSourceProvider(this.itemSqlParameterSourceProvider);
+		writer.setItemPreparedStatementSetter(this.itemPreparedStatementSetter);
+
+		if(mappedValue == 1) {
+			((JdbcBatchItemWriter<Map<String,Object>>)writer).setItemPreparedStatementSetter(new ColumnMapItemPreparedStatementSetter());
+		} else if(mappedValue == 2) {
+			writer.setItemSqlParameterSourceProvider(new BeanPropertyItemSqlParameterSourceProvider<>());
+		}
+
+		if(this.dataSource != null) {
+			this.namedParameterJdbcTemplate = new NamedParameterJdbcTemplate(this.dataSource);
+		}
+
+		writer.setJdbcTemplate(this.namedParameterJdbcTemplate);
+
+		return writer;
+	}
+}