spring-batch AggregateItem 源码
spring-batch AggregateItem 代码
文件路径：/spring-batch-samples/src/main/java/org/springframework/batch/sample/domain/multiline/AggregateItem.java
/*
* Copyright 2006-2014 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.sample.domain.multiline;
/**
* A wrapper type for an item that is used by {@link AggregateItemReader} to identify the
* start and end of an aggregate record.
*
* @see AggregateItemReader
* @author Dave Syer
*
*/
public class AggregateItem<T> {
@SuppressWarnings("rawtypes")
private static final AggregateItem FOOTER = new AggregateItem<Object>(false, true) {
@Override
public Object getItem() {
throw new IllegalStateException("Footer record has no item.");
}
};
/**
* @param <T> the type of item nominally wrapped
* @return a static {@link AggregateItem} that is a footer.
*/
@SuppressWarnings("unchecked")
public static <T> AggregateItem<T> getFooter() {
return FOOTER;
}
@SuppressWarnings("rawtypes")
private static final AggregateItem HEADER = new AggregateItem<Object>(true, false) {
@Override
public Object getItem() {
throw new IllegalStateException("Header record has no item.");
}
};
/**
* @param <T> the type of item nominally wrapped
* @return a static {@link AggregateItem} that is a header.
*/
@SuppressWarnings("unchecked")
public static <T> AggregateItem<T> getHeader() {
return HEADER;
}
private T item;
private boolean footer = false;
private boolean header = false;
/**
* @param item the item to wrap
*/
public AggregateItem(T item) {
super();
this.item = item;
}
public AggregateItem(boolean header, boolean footer) {
this(null);
this.header = header;
this.footer = footer;
}
/**
* Accessor for the wrapped item.
* @return the wrapped item
* @throws IllegalStateException if called on a record for which either
* {@link #isHeader()} or {@link #isFooter()} answers true.
*/
public T getItem() {
return item;
}
/**
* Responds true if this record is a footer in an aggregate.
* @return true if this is the end of an aggregate record.
*/
public boolean isFooter() {
return footer;
}
/**
* Responds true if this record is a header in an aggregate.
* @return true if this is the beginning of an aggregate record.
*/
public boolean isHeader() {
return header;
}
}
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