namegenerator.java

JGraph扩展应用。自定义Renderer,自定义视图View实现自定义工作流控件

/*
 * @(#)NameGenerator.java	1.9 03/12/19
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
package flow.graph.gui.graph.encoder;

import java.util.HashMap;
import java.util.IdentityHashMap;
import java.util.Map;

/**
 * A utility class which generates unique names for object instances.
 * The name will be a concatenation of the unqualified class name 
 * and an instance number.
 * <p>
 * For example, if the first object instance javax.swing.JButton 
 * is passed into <code>instanceName</code> then the returned
 * string identifier will be &quot;JButton0&quot;.
 * 
 * @version 1.9 12/19/03
 * @author Philip Milne
 */
public class NameGenerator { 

    private Map valueToName; 
    private Map nameToCount;
    
    public NameGenerator() {
        valueToName = new IdentityHashMap();
        nameToCount = new HashMap();
    }
    
    /**
     * Clears the name cache. Should be called to near the end of
     * the encoding cycle.
     */
    public void clear() { 
	valueToName.clear();
	nameToCount.clear();
    }
    
    /**
     * Returns the root name of the class.
     */
    public static String unqualifiedClassName(Class type) { 
        if (type.isArray()) {
            return unqualifiedClassName(type.getComponentType())+"Array"; 
        }
        String name = type.getName(); 
        return name.substring(name.lastIndexOf('.')+1); 
    }

    /**
     * Returns a String which capitalizes the first letter of the string.
     */
    public static String capitalize(String name) { 
	if (name == null || name.length() == 0) { 
	    return name; 
        }
	return name.substring(0, 1).toUpperCase() + name.substring(1);
    }
    
    /**
     * Returns a unique string which identifies the object instance.
     * Invocations are cached so that if an object has been previously
     * passed into this method then the same identifier is returned.
     * 
     * @param instance object used to generate string
     * @return a unique string representing the object
     */
    public String instanceName(Object instance) {         
        if (instance == null) {
            return "null"; 
        }
        if (instance instanceof Class) {
            return unqualifiedClassName((Class)instance); 
        }
        else { 
            String result = (String)valueToName.get(instance); 
            if (result != null) { 
                return result; 
            }
            Class type = instance.getClass(); 
            String className = unqualifiedClassName(type); 

            Object size = nameToCount.get(className); 
            int instanceNumber = (size == null) ? 0 : ((Integer)size).intValue() + 1; 
            nameToCount.put(className, new Integer(instanceNumber)); 

            result = className + instanceNumber; 
            valueToName.put(instance, result); 
            return result; 
        }
    }
}