Make RepositoryItemWriter use CrudRepository#saveAll by default

Before this commit, the `RepositoryItemWriter` did not use
`CrudRepository#saveAll` by default and one must override
`doWrite` and call it manually, which is not convenient.

This commit makes the writer use `CrudRepository#saveAll`
by default while keeping the possibility to use another
method if desired through the `methodName` parameter.

Resolves #3720

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2020 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.
@@ -36,6 +36,8 @@ import org.springframework.util.MethodInvoker;
  * </p>
  *
  * <p>
+ * By default, this writer will use {@link CrudRepository#saveAll(Iterable)}
+ * to save items, unless another method is selected with {@link #setMethodName(java.lang.String)}.
  * It depends on {@link org.springframework.data.repository.CrudRepository#saveAll(Iterable)}
  * method to store the items for the chunk.  Performance will be determined by that
  * implementation more than this writer.
@@ -107,6 +109,11 @@ public class RepositoryItemWriter<T> implements ItemWriter<T>, InitializingBean
 		if (logger.isDebugEnabled()) {
 			logger.debug("Writing to the repository with " + items.size() + " items.");
 		}
+		
+		if (this.methodName == null) {
+			this.repository.saveAll(items);
+			return;
+		}
 
 		MethodInvoker invoker = createMethodInvoker(repository, methodName);
 
@@ -122,6 +129,12 @@ public class RepositoryItemWriter<T> implements ItemWriter<T>, InitializingBean
 	@Override
 	public void afterPropertiesSet() throws Exception {
 		Assert.state(repository != null, "A CrudRepository implementation is required");
+		if (this.methodName != null) {
+			Assert.hasText(this.methodName, "methodName must not be empty.");
+		}
+		else {
+			logger.debug("No method name provided, CrudRepository.saveAll will be used.");
+		}
 	}
 
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2017-2018 the original author or authors.
+ * Copyright 2017-2020 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.
@@ -19,6 +19,9 @@ package org.springframework.batch.item.data.builder;
 
 import java.lang.reflect.Method;
 
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
+
 import org.springframework.batch.item.data.RepositoryItemWriter;
 import org.springframework.cglib.proxy.Enhancer;
 import org.springframework.cglib.proxy.MethodInterceptor;
@@ -36,6 +39,8 @@ import org.springframework.util.Assert;
  */
 public class RepositoryItemWriterBuilder<T> {
 
+	private static final Log logger = LogFactory.getLog(RepositoryItemWriterBuilder.class.getName());
+
 	private CrudRepository<T, ?> repository;
 
 	private String methodName;
@@ -104,12 +109,16 @@ public class RepositoryItemWriterBuilder<T> {
 			this.repository = this.repositoryMethodReference.getRepository();
 		}
 
-		Assert.hasText(this.methodName, "methodName is required.");
 		Assert.notNull(this.repository, "repository is required.");
 
 		RepositoryItemWriter<T> writer = new RepositoryItemWriter<>();
-		writer.setMethodName(this.methodName);
 		writer.setRepository(this.repository);
+		if (this.methodName != null) {
+			Assert.hasText(this.methodName, "methodName must not be empty.");
+			writer.setMethodName(this.methodName);
+		} else {
+			logger.debug("No method name provided, CrudRepository.saveAll will be used.");
+		}
 		return writer;
 	}