设计模式之 Visitor

package designpattern;

public interface Visitable 
{
	public void accept(Visitor visitor);
}



package designpattern;

public class StringElement implements Visitable 
{
	private String value;
	public StringElement(String string) 
	{
		value = string;
	}

	public String getValue()
	{
		return value;
	}


	//定义accept的具体内容 这里是很简单的一句调用
	public void accept(Visitor visitor) 
	{
		visitor.visitString(this);
	}
}




package designpattern;

public class FloatElement implements Visitable 
{
	public FloatElement(float f)
	{
		
	}
	
	private Float value;
	public FloatElement(Float value) 
	{
		this.value = value;
	}

	public Float getValue()
	{
		return value;
	}

	//定义accept的具体内容 这里是很简单的一句调用
	public void accept(Visitor visitor) 
	{
		visitor.visitFloat(this);
	}
}




package designpattern;

import java.util.*;

public interface Visitor 
{
	public void visitString(StringElement stringE);
	public void visitFloat(FloatElement floatE);
	public void visitCollection(Collection collection);
}




package designpattern;

import java.util.*;

public class ConcreteVisitor implements Visitor
{
	public static void main(String[] args)
	{
		List list = new ArrayList();
		list.add(new StringElement("xuxiaolei"));
		list.add(new FloatElement(100f));
		
		ConcreteVisitor vistor = new ConcreteVisitor();
		vistor.visitCollection(list);
	}
	
	public void visitString(StringElement stringE)
	{
		System.out.println(stringE.getValue());
	}
	
	public void visitFloat(FloatElement floatE)
	{
		System.out.println(floatE.getValue());
	}
	
	public void visitCollection(Collection collection)
	{
		Iterator iterator = collection.iterator();
		while (iterator.hasNext())
		{
			Object o = iterator.next();
			if (o instanceof Visitable)
			{
				((Visitable)o).accept(this);
			}
		}
	}
	
	 
}