Add builder for JmsItemReader

resolves BATCH-2602

spring-batch-infrastructure/src/main/java/org/springframework/batch/item/jms/builder/JmsItemReaderBuilder.java

@@ -0,0 +1,81 @@
+/*
+ * 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.jms.builder;
+
+import javax.jms.Message;
+
+import org.springframework.batch.item.jms.JmsItemReader;
+import org.springframework.jms.core.JmsOperations;
+import org.springframework.util.Assert;
+
+/**
+ * Creates a fully qualified JmsItemReader.
+ *
+ * @author Glenn Renfro
+ *
+ * @since 4.0
+ */
+public class JmsItemReaderBuilder<T> {
+
+	protected Class<? extends T> itemType;
+
+	protected JmsOperations jmsTemplate;
+
+	/**
+	 * Establish the JMS template that will be used by the JmsItemReader.
+	 *
+	 * @param jmsTemplate a {@link JmsOperations} instance
+	 * @return this instance for method chaining.
+	 * @see JmsItemReader#setJmsTemplate(JmsOperations)
+	 */
+	public JmsItemReaderBuilder<T> jmsTemplate(JmsOperations jmsTemplate) {
+		this.jmsTemplate = jmsTemplate;
+
+		return this;
+	}
+
+	/**
+	 * Set the expected type of incoming message payloads. Set this to {@link Message} to
+	 * receive the raw underlying message.
+	 *
+	 * @param itemType the java class of the items to be delivered. Typically the same as
+	 * the class parameter
+	 * @return this instance for method chaining.
+	 *
+	 * @throws IllegalStateException if the message payload is of the wrong type.
+	 * @see JmsItemReader#setItemType(Class)
+	 */
+	public JmsItemReaderBuilder<T> itemType(Class<? extends T> itemType) {
+		this.itemType = itemType;
+
+		return this;
+	}
+
+	/**
+	 * Returns a fully constructed {@link JmsItemReader}.
+	 *
+	 * @return a new {@link JmsItemReader}
+	 */
+	public JmsItemReader<T> build() {
+		Assert.notNull(this.jmsTemplate, "jmsTemplate is required.");
+		JmsItemReader<T> jmsItemReader = new JmsItemReader<>();
+
+		jmsItemReader.setItemType(this.itemType);
+		jmsItemReader.setJmsTemplate(this.jmsTemplate);
+		return jmsItemReader;
+	}
+}

spring-batch-infrastructure/src/test/java/org/springframework/batch/item/jms/builder/JmsItemReaderBuilderTests.java

@@ -0,0 +1,104 @@
+/*
+ * 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.jms.builder;
+
+import java.util.Date;
+
+import javax.jms.Message;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import org.springframework.batch.item.jms.JmsItemReader;
+import org.springframework.jms.core.JmsOperations;
+import org.springframework.jms.core.JmsTemplate;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.fail;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+/**
+ * @author Glenn Renfro
+ */
+public class JmsItemReaderBuilderTests {
+
+	private JmsOperations defaultJmsTemplate;
+
+	@Before
+	public void setupJmsTemplate() {
+		this.defaultJmsTemplate = mock(JmsOperations.class);
+		when(this.defaultJmsTemplate.receiveAndConvert()).thenReturn("foo");
+	}
+
+	@Test
+	public void testBasicRead() {
+		JmsItemReader<String> itemReader = new JmsItemReaderBuilder<String>().jmsTemplate(this.defaultJmsTemplate)
+				.build();
+		assertEquals("foo", itemReader.read());
+	}
+
+	@Test
+	public void testSetItemSubclassType() {
+		JmsOperations jmsTemplate = mock(JmsOperations.class);
+
+		Date date = new java.sql.Date(0L);
+		when(jmsTemplate.receiveAndConvert()).thenReturn(date);
+
+		JmsItemReader<Date> itemReader = new JmsItemReaderBuilder<Date>().jmsTemplate(jmsTemplate).itemType(Date.class)
+				.build();
+		assertEquals(date, itemReader.read());
+	}
+
+	@Test
+	public void testSetItemTypeMismatch() {
+		JmsItemReader<Date> itemReader = new JmsItemReaderBuilder<Date>().jmsTemplate(this.defaultJmsTemplate)
+				.itemType(Date.class).build();
+		try {
+			itemReader.read();
+			fail("Expected IllegalStateException");
+		}
+		catch (IllegalStateException e) {
+			// expected
+			assertTrue(e.getMessage().indexOf("wrong type") >= 0);
+		}
+	}
+
+	@Test
+	public void testMessageType() {
+		JmsOperations jmsTemplate = mock(JmsOperations.class);
+		Message message = mock(Message.class);
+		when(jmsTemplate.receive()).thenReturn(message);
+
+		JmsItemReader<Message> itemReader = new JmsItemReaderBuilder<Message>().jmsTemplate(jmsTemplate)
+				.itemType(Message.class).build();
+		assertEquals(message, itemReader.read());
+	}
+
+	@Test
+	public void testNullJmsTemplate() {
+		try {
+			new JmsItemReaderBuilder<String>().itemType(String.class).build();
+			fail("IllegalArgumentException should have been thrown");
+		}
+		catch (IllegalArgumentException ise) {
+			assertEquals("IllegalArgumentException message did not match the expected result.",
+					"jmsTemplate is required.", ise.getMessage());
+		}
+	}
+}