Druid/src/main/java/com/alibaba/druid/util/LazyCompositeData.java

/*
 * Copyright 2011 Alibaba Group.
 *
 * 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
 *
 *      http://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 com.alibaba.druid.util;

import java.io.Serializable;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Set;

import javax.management.openmbean.CompositeData;
import javax.management.openmbean.CompositeType;
import javax.management.openmbean.OpenType;
import javax.management.openmbean.TabularType;

/**
 * This abstract class provides the implementation of the CompositeData
 * interface. A CompositeData object will be lazily created only when the
 * CompositeData interface is used.
 * 
 * Classes that extends this abstract class will implement the
 * getCompositeData() method. The object returned by the getCompositeData() is
 * an instance of CompositeData such that the instance serializes itself as the
 * type CompositeDataSupport.
 */
public abstract class LazyCompositeData implements CompositeData, Serializable {

	private CompositeData compositeData;

	// Implementation of the CompositeData interface
	public boolean containsKey(String key) {
		return compositeData().containsKey(key);
	}

	public boolean containsValue(Object value) {
		return compositeData().containsValue(value);
	}

	public boolean equals(Object obj) {
		return compositeData().equals(obj);
	}

	public Object get(String key) {
		return compositeData().get(key);
	}

	public Object[] getAll(String[] keys) {
		return compositeData().getAll(keys);
	}

	public CompositeType getCompositeType() {
		return compositeData().getCompositeType();
	}

	public int hashCode() {
		return compositeData().hashCode();
	}

	public String toString() {
		/** FIXME: What should this be?? */
		return compositeData().toString();
	}

	public Collection<?> values() {
		return compositeData().values();
	}

	/*
	 * Lazy creation of a CompositeData object only when the CompositeData
	 * interface is used.
	 */
	private synchronized CompositeData compositeData() {
		if (compositeData != null)
			return compositeData;
		compositeData = getCompositeData();
		return compositeData;
	}

	/**
	 * Designate to a CompositeData object when writing to an output stream
	 * during serialization so that the receiver only requires JMX 1.2 classes
	 * but not any implementation specific class.
	 */
	protected Object writeReplace() throws java.io.ObjectStreamException {
		return compositeData();
	}

	/**
	 * Returns the CompositeData representing this object. The returned
	 * CompositeData object must be an instance of
	 * javax.management.openmbean.CompositeDataSupport class so that no
	 * implementation specific class is required for unmarshalling besides JMX
	 * 1.2 classes.
	 */
	protected abstract CompositeData getCompositeData();

	// Helper methods
	static String getString(CompositeData cd, String itemName) {
		if (cd == null)
			throw new IllegalArgumentException("Null CompositeData");

		return (String) cd.get(itemName);
	}

	static boolean getBoolean(CompositeData cd, String itemName) {
		if (cd == null)
			throw new IllegalArgumentException("Null CompositeData");

		return ((Boolean) cd.get(itemName)).booleanValue();
	}

	static long getLong(CompositeData cd, String itemName) {
		if (cd == null)
			throw new IllegalArgumentException("Null CompositeData");

		return ((Number) cd.get(itemName)).longValue();
	}

	static int getInt(CompositeData cd, String itemName) {
		if (cd == null)
			throw new IllegalArgumentException("Null CompositeData");

		return ((Number) cd.get(itemName)).intValue();
	}

	/**
	 * Compares two CompositeTypes and returns true if all items in type1 exist
	 * in type2 and their item types are the same.
	 */
	protected static boolean isTypeMatched(CompositeType type1, CompositeType type2) {
		if (type1 == type2)
			return true;

		// We can't use CompositeType.isValue() since it returns false
		// if the type name doesn't match.
		Set<?> allItems = type1.keySet();

		// Check all items in the type1 exist in type2
		if (!type2.keySet().containsAll(allItems))
			return false;

		for (Iterator<?> iter = allItems.iterator(); iter.hasNext();) {
			String item = (String) iter.next();
			OpenType<?> ot1 = type1.getType(item);
			OpenType<?> ot2 = type2.getType(item);
			if (ot1 instanceof CompositeType) {
				if (!(ot2 instanceof CompositeType))
					return false;
				if (!isTypeMatched((CompositeType) ot1, (CompositeType) ot2))
					return false;
			} else if (ot1 instanceof TabularType) {
				if (!(ot2 instanceof TabularType))
					return false;
				if (!isTypeMatched((TabularType) ot1, (TabularType) ot2))
					return false;
			} else if (!ot1.equals(ot2)) {
				return false;
			}
		}
		return true;
	}

	protected static boolean isTypeMatched(TabularType type1, TabularType type2) {
		if (type1 == type2)
			return true;

		List<String> list1 = type1.getIndexNames();
		List<String> list2 = type2.getIndexNames();

		// check if the list of index names are the same
		if (!list1.equals(list2))
			return false;

		return isTypeMatched(type1.getRowType(), type2.getRowType());
	}
}