Make transaction manager optional in Tasklet and Chunk-Oriented steps

Before this commit, it was required to provide a transaction
manager in tasklet and chunk-oriented steps even if transactions
are not needed.

This commit makes that optional by using a no-op transaction
manager by default.

Resolves #4974

Author: fmbenhassine

spring-batch-core/src/main/java/org/springframework/batch/core/step/builder/StepBuilder.java

@@ -65,6 +65,16 @@ public TaskletStepBuilder tasklet(Tasklet tasklet, PlatformTransactionManager tr
 		return new TaskletStepBuilder(this).tasklet(tasklet, transactionManager);
 	}
 
+	/**
+	 * Build a step with a custom tasklet, not necessarily item processing.
+	 * @param tasklet a tasklet
+	 * @return a {@link TaskletStepBuilder}
+	 * @since 6.0
+	 */
+	public TaskletStepBuilder tasklet(Tasklet tasklet) {
+		return new TaskletStepBuilder(this).tasklet(tasklet);
+	}
+
 	/**
 	 * Build a step that processes items in chunks with the size provided. To extend the
 	 * step to being fault tolerant, call the {@link SimpleStepBuilder#faultTolerant()}

spring-batch-core/src/main/java/org/springframework/batch/core/step/builder/TaskletStepBuilder.java

@@ -49,6 +49,16 @@ public TaskletStepBuilder tasklet(Tasklet tasklet, PlatformTransactionManager tr
 		return this;
 	}
 
+	/**
+	 * @param tasklet the tasklet to use
+	 * @return this for fluent chaining
+	 * @since 6.0
+	 */
+	public TaskletStepBuilder tasklet(Tasklet tasklet) {
+		this.tasklet = tasklet;
+		return this;
+	}
+
 	@Override
 	protected TaskletStepBuilder self() {
 		return this;

spring-batch-core/src/main/java/org/springframework/batch/core/step/item/ChunkOrientedStep.java

@@ -111,11 +111,11 @@ public class ChunkOrientedStep<I, O> extends AbstractStep {
 	/*
 	 * Transaction related parameters
 	 */
-	private PlatformTransactionManager transactionManager = new ResourcelessTransactionManager();
+	private PlatformTransactionManager transactionManager;
 
 	private TransactionTemplate transactionTemplate;
 
-	private TransactionAttribute transactionAttribute = new DefaultTransactionAttribute();
+	private TransactionAttribute transactionAttribute;
 
 	/*
 	 * Chunk related parameters
@@ -309,7 +309,14 @@ public void registerSkipListener(SkipListener<I, O> skipListener) {
 	@Override
 	public void afterPropertiesSet() throws Exception {
 		super.afterPropertiesSet();
-		Assert.notNull(this.transactionManager, "Transaction manager must not be null");
+		if (this.transactionManager == null) {
+			logger.info("No transaction manager has been set. Defaulting to ResourcelessTransactionManager.");
+			this.transactionManager = new ResourcelessTransactionManager();
+		}
+		if (this.transactionAttribute == null) {
+			logger.info("No transaction attribute has been set. Defaulting to DefaultTransactionAttribute.");
+			this.transactionAttribute = new DefaultTransactionAttribute();
+		}
 		Assert.isTrue(this.chunkSize > 0, "Chunk size must be greater than 0");
 		Assert.notNull(this.itemReader, "Item reader must not be null");
 		Assert.notNull(this.itemWriter, "Item writer must not be null");

spring-batch-core/src/main/java/org/springframework/batch/core/step/tasklet/TaskletStep.java

@@ -41,6 +41,7 @@
 import org.springframework.batch.repeat.RepeatOperations;
 import org.springframework.batch.repeat.RepeatStatus;
 import org.springframework.batch.repeat.support.RepeatTemplate;
+import org.springframework.batch.support.transaction.ResourcelessTransactionManager;
 import org.springframework.transaction.PlatformTransactionManager;
 import org.springframework.transaction.TransactionStatus;
 import org.springframework.transaction.interceptor.DefaultTransactionAttribute;
@@ -49,7 +50,6 @@
 import org.springframework.transaction.support.TransactionSynchronization;
 import org.springframework.transaction.support.TransactionSynchronizationManager;
 import org.springframework.transaction.support.TransactionTemplate;
-import org.springframework.util.Assert;
 
 import java.util.concurrent.Semaphore;
 
@@ -118,7 +118,10 @@ public TaskletStep(String name) {
 	@Override
 	public void afterPropertiesSet() throws Exception {
 		super.afterPropertiesSet();
-		Assert.state(transactionManager != null, "A transaction manager must be provided");
+		if (this.transactionManager == null) {
+			logger.info("No transaction manager has been set.  Defaulting to ResourcelessTransactionManager.");
+			this.transactionManager = new ResourcelessTransactionManager();
+		}
 	}
 
 	/**

spring-batch-samples/src/main/java/org/springframework/batch/samples/helloworld/HelloWorldJobConfiguration.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023 the original author or authors.
+ * Copyright 2023-2025 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.
@@ -15,9 +15,10 @@
  */
 package org.springframework.batch.samples.helloworld;
 
+import org.springframework.batch.core.configuration.annotation.EnableBatchProcessing;
+import org.springframework.batch.core.configuration.annotation.EnableJdbcJobRepository;
 import org.springframework.batch.core.job.Job;
 import org.springframework.batch.core.step.Step;
-import org.springframework.batch.core.configuration.annotation.*;
 import org.springframework.batch.core.job.builder.JobBuilder;
 import org.springframework.batch.core.repository.JobRepository;
 import org.springframework.batch.core.step.builder.StepBuilder;
@@ -26,7 +27,6 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
-import org.springframework.jdbc.support.JdbcTransactionManager;
 
 @Configuration
 @EnableBatchProcessing
@@ -35,11 +35,11 @@
 public class HelloWorldJobConfiguration {
 
 	@Bean
-	public Step step(JobRepository jobRepository, JdbcTransactionManager transactionManager) {
+	public Step step(JobRepository jobRepository) {
 		return new StepBuilder("step", jobRepository).tasklet((contribution, chunkContext) -> {
 			System.out.println("Hello world!");
 			return RepeatStatus.FINISHED;
-		}, transactionManager).build();
+		}).build();
 	}
 
 	@Bean