spring-batch KeyValueItemWriter 源码
spring-batch KeyValueItemWriter 代码
文件路径：/spring-batch-infrastructure/src/main/java/org/springframework/batch/item/KeyValueItemWriter.java
/*
* Copyright 2002-2021 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;
import java.util.List;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.core.convert.converter.Converter;
import org.springframework.util.Assert;
/**
* A base class to implement any {@link ItemWriter} that writes to a key value store using
* a {@link Converter} to derive a key from an item
*
* @author David Turanski
* @since 2.2
*
*/
public abstract class KeyValueItemWriter<K, V> implements ItemWriter<V>, InitializingBean {
protected Converter<V, K> itemKeyMapper;
protected boolean delete;
/*
* (non-Javadoc)
*
* @see org.springframework.batch.item.ItemWriter#write(java.util.List)
*/
@Override
public void write(List<? extends V> items) throws Exception {
if (items == null) {
return;
}
for (V item : items) {
K key = itemKeyMapper.convert(item);
writeKeyValue(key, item);
}
flush();
}
/**
* Flush items to the key/value store.
* @throws Exception if unable to flush items
*/
protected void flush() throws Exception {
}
/**
* Subclasses implement this method to write each item to key value store
* @param key the key
* @param value the item
*/
protected abstract void writeKeyValue(K key, V value);
/**
* afterPropertiesSet() hook
*/
protected abstract void init();
/**
* Set the {@link Converter} to use to derive the key from the item
* @param itemKeyMapper the {@link Converter} used to derive a key from an item.
*/
public void setItemKeyMapper(Converter<V, K> itemKeyMapper) {
this.itemKeyMapper = itemKeyMapper;
}
/**
* Sets the delete flag to have the item writer perform deletes
* @param delete if true {@link ItemWriter} will perform deletes, if false not to
* perform deletes.
*/
public void setDelete(boolean delete) {
this.delete = delete;
}
/*
* (non-Javadoc)
*
* @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet()
*/
@Override
public void afterPropertiesSet() throws Exception {
Assert.notNull(itemKeyMapper, "itemKeyMapper requires a Converter type.");
init();
}
}
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