import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
@SuppressWarnings({"rawtypes", "unchecked"})
@Override
public T read() throws Exception, UnexpectedInputException, ParseException,
NonTransientResourceException {
	T item;
	//TODO Separate two steps and refactor
	if(currentDelegate == null || (item = currentDelegate.read()) == null) {
		logger.debug("Loading new item reader");
		try {
			if(currentDelegate != null && ItemStream.class.isAssignableFrom(currentDelegate.getClass())) {
				((ItemStream) currentDelegate).close();
			}
			currentDelegate = delegates.remove(0);
			logger.info("The current ItemReader is now " +  currentDelegate);
			if(currentDelegate != null && ItemStream.class.isAssignableFrom(currentDelegate.getClass())) {
				((ItemStream) currentDelegate).open(new ExecutionContext());
			}
		} catch (IndexOutOfBoundsException e) {
			//if there are no more delegates
			logger.info("No more readers, returning null");
			return null;
		}
		item = read();
	}
	//If targetType is null use the first delegate to define the expected type
	if (targetType == null) {
		targetType = (Class) item.getClass();
	} else {
		if(!targetType.isInstance(item)) {
			logger.debug("Attempting to cast " + item + " to " + targetType);
			item = (T) conversionService.convert(item, targetType);
		}
	}
	logger.debug("Returning " + item);
	return item;
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
/**
 * 모든 Reader에 open을 호출함 
 * 
 * @throws ItemStreamException
 */
public void open(ExecutionContext executionContext)
		throws ItemStreamException {
	for (ItemStream itemStream : itemReaderList) {
		itemStream.open(executionContext);
	}
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
@Override
public void open(ExecutionContext sExecutionContext) throws ItemStreamException {
    if (delegate instanceof ItemStream) {
        ((ItemStream) delegate).open(sExecutionContext);
    }
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
@Override
public void update(ExecutionContext sExecutionContext) throws ItemStreamException {
    if (delegate instanceof ItemStream) {
        ((ItemStream) delegate).update(sExecutionContext);
    }
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
@Override
public void close() throws ItemStreamException {
    if (delegate instanceof ItemStream) {
        ((ItemStream) delegate).close();
    }
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
@Override
public synchronized void open(ExecutionContext sExecutionContext) {
    delegateExhausted = false;
    ((ItemStream) delegate).open(sExecutionContext);
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
@Override
public synchronized void update(ExecutionContext sExecutionContext) {
    ((ItemStream) delegate).update(sExecutionContext);
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
@Override
public synchronized void close() {
    delegateExhausted = false;
    ((ItemStream) delegate).close();
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
@Before
public void setUp() {
	((ItemStream) multiLineNodeListItemReader).open(new ExecutionContext());
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
@After
public void tearDown() {
	((ItemStream) multiLineNodeListItemReader).close();
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
@Override
public void close() throws ItemStreamException {
	if (this.delegate instanceof ItemStream) {
           ((ItemStream)this.delegate).close();
	}
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
@Override
public void open(ExecutionContext executionContext) throws ItemStreamException {
	if (this.delegate instanceof ItemStream) {
           ((ItemStream)this.delegate).open(executionContext);
	}
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
@Override
public void update(ExecutionContext executionContext) throws ItemStreamException {
	 if (this.delegate instanceof ItemStream) {
            ((ItemStream)this.delegate).update(executionContext);
    }
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
@Before
public void setUp() {
    ((ItemStream) reader).open(new ExecutionContext());
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
@After
public void tearDown() {
    ((ItemStream) reader).close();
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
/**
 * 변경된 사항을 등록된 모든 Reader에 update함 
 * 
 * @see org.springframework.batch.item.ItemStream#update(ExecutionContext)
 */
public void update(ExecutionContext executionContext) {
	for (ItemStream itemStream : itemReaderList) {
		itemStream.update(executionContext);
	}
}
 

import org.springframework.batch.item.ItemStream; //导入依赖的package包/类
/**
 * 모든 Reader에 close를 호출함 
 * 
 * @throws ItemStreamException
 */
public void close() throws ItemStreamException {
	for (ItemStream itemStream : itemReaderList) {
		itemStream.close();
	}
}