spring-batch CompositeItemWriter 源码

spring-batch CompositeItemWriter 代码

文件路径：/spring-batch-infrastructure/src/main/java/org/springframework/batch/item/support/CompositeItemWriter.java

/*
 * Copyright 2006-2022 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 org.springframework.batch.item.support;

import org.springframework.batch.item.ExecutionContext;
import org.springframework.batch.item.ItemStream;
import org.springframework.batch.item.ItemStreamException;
import org.springframework.batch.item.ItemStreamWriter;
import org.springframework.batch.item.ItemWriter;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.util.Assert;

import java.util.Arrays;
import java.util.List;

/**
 * Calls a collection of {@link ItemWriter}s in fixed-order sequence.<br>
 * <br>
 *
 * The implementation is thread-safe if all delegates are thread-safe.
 *
 * @author Robert Kasanicky
 * @author Dave Syer
 */
public class CompositeItemWriter<T> implements ItemStreamWriter<T>, InitializingBean {

	private List<ItemWriter<? super T>> delegates;

	private boolean ignoreItemStream = false;

	/**
	 * Default constrcutor
	 */
	public CompositeItemWriter() {

	}

	/**
	 * Convenience constructor for setting the delegates.
	 * @param delegates the list of delegates to use.
	 */
	public CompositeItemWriter(List<ItemWriter<? super T>> delegates) {
		setDelegates(delegates);
	}

	/**
	 * Convenience constructor for setting the delegates.
	 * @param delegates the array of delegates to use.
	 */
	public CompositeItemWriter(ItemWriter<? super T>... delegates) {
		this(Arrays.asList(delegates));
	}

	/**
	 * Establishes the policy whether to call the open, close, or update methods for the
	 * item writer delegates associated with the CompositeItemWriter.
	 * @param ignoreItemStream if false the delegates' open, close, or update methods will
	 * be called when the corresponding methods on the CompositeItemWriter are called. If
	 * true the delegates' open, close, nor update methods will not be called (default is
	 * false).
	 */
	public void setIgnoreItemStream(boolean ignoreItemStream) {
		this.ignoreItemStream = ignoreItemStream;
	}

	@Override
	public void write(List<? extends T> item) throws Exception {
		for (ItemWriter<? super T> writer : delegates) {
			writer.write(item);
		}
	}

	@Override
	public void afterPropertiesSet() throws Exception {
		Assert.notNull(delegates, "The 'delegates' may not be null");
		Assert.notEmpty(delegates, "The 'delegates' may not be empty");
	}

	/**
	 * The list of item writers to use as delegates. Items are written to each of the
	 * delegates.
	 * @param delegates the list of delegates to use. The delegates list must not be null
	 * nor be empty.
	 */
	public void setDelegates(List<ItemWriter<? super T>> delegates) {
		this.delegates = delegates;
	}

	@Override
	public void close() throws ItemStreamException {
		for (ItemWriter<? super T> writer : delegates) {
			if (!ignoreItemStream && (writer instanceof ItemStream)) {
				((ItemStream) writer).close();
			}
		}
	}

	@Override
	public void open(ExecutionContext executionContext) throws ItemStreamException {
		for (ItemWriter<? super T> writer : delegates) {
			if (!ignoreItemStream && (writer instanceof ItemStream)) {
				((ItemStream) writer).open(executionContext);
			}
		}
	}

	@Override
	public void update(ExecutionContext executionContext) throws ItemStreamException {
		for (ItemWriter<? super T> writer : delegates) {
			if (!ignoreItemStream && (writer instanceof ItemStream)) {
				((ItemStream) writer).update(executionContext);
			}
		}
	}

}

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