juneau-core/juneau-marshall/src/main/java/org/apache/juneau/pojotools/PojoViewer.java

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// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
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// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
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package org.apache.juneau.pojotools;

import java.lang.reflect.*;
import java.util.*;

import org.apache.juneau.*;
import org.apache.juneau.internal.*;

/**
 * Designed to provide paging on POJOs consisting of arrays and collections.
 *
 * <p>
 * Allows you to quickly return subsets of arrays and collections based on position/limit arguments.
 */
@SuppressWarnings({"unchecked","rawtypes"})
public final class PojoViewer implements PojoTool<ViewArgs> {

	@Override /* PojoTool */
	public Object run(BeanSession session, Object input, ViewArgs args) {

		if (input == null)
			return null;

		List<String> view = args.getView();
		ClassMeta type = session.getClassMetaForObject(input);

		if (type.isBeanMap())
			return new DelegateBeanMap(((BeanMap)input).getBean(), session).filterKeys(view);
		if (type.isMap())
			return new DelegateMap((Map)input, session).filterKeys(view);
		if (type.isBean())
			return new DelegateBeanMap(input, session).filterKeys(view);

		ArrayList<Object> l = null;

		if (type.isArray()) {
			int size = Array.getLength(input);
			l = new ArrayList<>(size);
			for (int i = 0; i < size; i++)
				l.add(Array.get(input, i));
		} else if (type.isCollection()) {
			Collection c = (Collection)input;
			l = new ArrayList<>(c.size());
			for (Object o : c)
				l.add(o);
		} else {
			return input;
		}

		for (ListIterator li = l.listIterator(); li.hasNext();) {
			Object o = li.next();
			ClassMeta cm2 = session.getClassMetaForObject(o);

			if (cm2 == null)
				o = null;
			else if (cm2.isBeanMap())
				o = new DelegateBeanMap(((BeanMap)o).getBean(), session).filterKeys(view);
			else if (cm2.isMap())
				o = new DelegateMap((Map)o, session).filterKeys(view);
			else if (cm2.isBean())
				o = new DelegateBeanMap(o, session).filterKeys(view);

			li.set(o);
		}

		return l;
	}
}