genericmenuloader.java

一个实用工具类

/*
 * Copyright (C) butor.com. All rights reserved.
 *
 * This software is published under the terms of the GNU Library General
 * Public License (GNU LGPL), a copy of which has been included with this
 * distribution in the LICENSE.txt file. 
 */


package org.butor.web.menu;

import java.util.ArrayList;
import java.util.Collection;

import org.butor.log.Log;


/**
 * This class is used to build any item hierarchy such as an menu hierarchy. 
 *
 * @author Nguyen The Hung
 */
public abstract class GenericMenuLoader {

	/** 
	 * Top node (dummy node, i.e. placeholder for all children nodes).
	 */
	private Branch f_topNode;
	/**
	 * List of nodes as read from the config file.
	 */
	private ArrayList f_listOfNodes;
	
	
	/**
	 * Constructor for GenericMenuLoader.
	 */
	public GenericMenuLoader() {
		
		super();
		f_topNode = new Branch("", "");
		f_listOfNodes = new ArrayList();
	}
	
	/**
	 * Clear the list of nodes.
	 */
	protected void clear() {
		
		Log.logStr(Log.LOG_LEVEL_LOW, this, Log.LOG_TYPE_INFO, "clear()", "");
		
		f_listOfNodes.clear();
	}
	
	/**
	 * Add a node to the list.
	 * @param node org.butor.wak.menu.Branch
	 */
	protected void add(Branch node) {
		
		if (node == null) {
			Log.logStr(this, Log.LOG_TYPE_ERROR, "add()", "Cannot add node [null].");
			return;
		}
		
		Log.logStr(Log.LOG_LEVEL_LOW, this, Log.LOG_TYPE_INFO, "add()", "Branch = [" + node.toString() + "].");
		
		f_listOfNodes.add(node);
	}
	
	/**
	 * Remove a node.
	 * @param node org.butor.wak.menu.Branch
	 * @return boolean 
	 */
	protected boolean remove(Branch node) {

		if (node == null) {
			Log.logStr(this, Log.LOG_TYPE_ERROR, "remove()", "Cannot remove node [null].");
			return false;
		}
		
		return remove(node.getName());
	}
	
	/**
	 * Remove a node.
	 * @param name java.lang.String
	 * @return boolean
	 */
	protected boolean remove(String name) {
		
		if (name == null) {
			Log.logStr(this, Log.LOG_TYPE_ERROR, "remove()", "Cannot remove node. Name = [null].");
			return false;
		}
		
		Log.logStr(Log.LOG_LEVEL_LOW, this, Log.LOG_TYPE_INFO, "remove()", name);
		
		for (int i = 0; i < f_listOfNodes.size(); i++) {
			if (name.equals(((Branch) f_listOfNodes.get(i)).getName())) {
				f_listOfNodes.remove(i);
				return true;
			}
		}
		
		Log.logStr(Log.LOG_LEVEL_LOW, this, Log.LOG_TYPE_INFO, "remove()", name + " not found.");
		
		return false;
	}
	
	/**
	 * It is up to the sub-class implementation to decide whether the node
	 * should be displayed.
	 */
	protected abstract boolean shouldDisplayNode(IBranch node);

	/**
	 * Recursively build the node hierarchy expanding downward.
	 * @param topNode org.butor.wak.menu.Branch
	 * @param list java.util.ArrayList
	 */
	private void buildHierarchy(Branch topNode, ArrayList list) {
		
		Log.logStr(Log.LOG_LEVEL_LOW, this, Log.LOG_TYPE_INFO, "buildHierarchy()", "");
		
		// Find all the nodes that contain the parent name = top node name
		String topNodeName = topNode.getName();
		for (int i = 0; i < list.size(); i++) {
			Branch node = (Branch) list.get(i);
			String nodeName = node.getName();
			
			// if node without name then bypass
			if (nodeName != null && !nodeName.equals("")) {
				String parentName = node.getParentName();
				
				if (parentName == null) {
					parentName = ""; // default to top-level
				}
				if (parentName.equals(topNodeName)) {
					// Note: if the node is not displayed then all the children will not
					// be displayed as well.
					if (shouldDisplayNode(node)) {
						topNode.addBranch(node);
						buildHierarchy(node, list);
					}
				}
			}
		}
	}
	
	/**
	 * Build the hierarchy
	 */
	protected void build() {
		
		f_topNode.removeAllChildren();
		buildHierarchy(f_topNode, f_listOfNodes);
	}
	
	/**
	 * Return the list of hierarchy nodes.
	 * @return java.util.Collection
	 */
	public Collection getHierarchy() {
		return f_topNode.getChildren();
	}

	/**
	 * Return the list of nodes.
	 * @return java.util.Collection
	 */
	public Collection getList() {
		return f_listOfNodes;
	}
}