Add support for in-memory Batch infrastructure

This commit moves the existing JDBC-based Spring Batch infrastructure
to a new 'spring-boot-batch-jdbc' module, while the existing module
only offers in-memory (aka resourceless) support.

The commit also updates the reference guide to provide some more
information about what's available and how to use it.

Closes gh-46307

smoke-test/spring-boot-smoke-test-batch-jdbc/build.gradle

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2012-present 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.
+ */
+
+plugins {
+	id "java"
+}
+
+description = "Spring Boot Batch with JDBC smoke test"
+
+dependencies {
+	implementation(project(":starter:spring-boot-starter-batch-jdbc"))
+
+	runtimeOnly("org.hsqldb:hsqldb")
+
+	testImplementation(project(":starter:spring-boot-starter-test"))
+}

smoke-test/spring-boot-smoke-test-batch-jdbc/src/main/java/smoketest/batch/SampleBatchApplication.java

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2012-present 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 smoketest.batch;
+
+import org.springframework.batch.core.job.Job;
+import org.springframework.batch.core.job.builder.JobBuilder;
+import org.springframework.batch.core.repository.JobRepository;
+import org.springframework.batch.core.step.Step;
+import org.springframework.batch.core.step.builder.StepBuilder;
+import org.springframework.batch.core.step.tasklet.Tasklet;
+import org.springframework.batch.repeat.RepeatStatus;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+import org.springframework.transaction.PlatformTransactionManager;
+
+@SpringBootApplication
+public class SampleBatchApplication {
+
+	@Bean
+	Tasklet tasklet() {
+		return (contribution, context) -> RepeatStatus.FINISHED;
+	}
+
+	@Bean
+	Job job(JobRepository jobRepository, Step step) {
+		return new JobBuilder("job", jobRepository).start(step).build();
+	}
+
+	@Bean
+	Step step1(JobRepository jobRepository, Tasklet tasklet, PlatformTransactionManager transactionManager) {
+		return new StepBuilder("step1", jobRepository).tasklet(tasklet, transactionManager).build();
+	}
+
+	public static void main(String[] args) {
+		// System.exit is common for Batch applications since the exit code can be used to
+		// drive a workflow
+		System.exit(SpringApplication.exit(SpringApplication.run(SampleBatchApplication.class, args)));
+	}
+
+}

smoke-test/spring-boot-smoke-test-batch-jdbc/src/main/java/smoketest/batch/package-info.java

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2012-present 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.
+ */
+
+@NullMarked
+package smoketest.batch;
+
+import org.jspecify.annotations.NullMarked;

smoke-test/spring-boot-smoke-test-batch-jdbc/src/test/java/smoketest/batch/SampleBatchApplicationTests.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 2012-present 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 smoketest.batch;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.test.system.CapturedOutput;
+import org.springframework.boot.test.system.OutputCaptureExtension;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@ExtendWith(OutputCaptureExtension.class)
+class SampleBatchApplicationTests {
+
+	@Test
+	void testDefaultSettings(CapturedOutput output) {
+		assertThat(SpringApplication.exit(SpringApplication.run(SampleBatchApplication.class))).isZero();
+		assertThat(output).contains("completed with the following parameters");
+	}
+
+}