import java.util.ArrayList;
import java.util.List;
abstract class IVisitor
{
public abstract void visit(Banana banana);
public abstract void visit(Rice rice);
public void visit(IElement iElement)
{
System.out.println("什么东西，怎么吃啊？");
}
}
class Human extends IVisitor
{
public void visit(Banana banana)
{
System.out.println("人类扒开皮吃香蕉");
}
public void visit(Rice rice)
{
System.out.println("人类用工具吃米饭");
}
}
class Monkey extends IVisitor
{
public void visit(Banana banana)
{
System.out.println("猴子不扒皮就吃");
}
public void visit(Rice rice)
{
System.out.println("猴子用手抓米饭吃");
}
}
interface IElement
{
public void accept(IVisitor iVisitor);
}
class Banana implements IElement
{
public void accept(IVisitor iVisitor)
{
iVisitor.visit(this);
}
}
class Rice implements IElement
{
public void accept(IVisitor iVisitor)
{
iVisitor.visit(this);
}
}
class Apple implements IElement
{
public void accept(IVisitor iVisitor)
{
iVisitor.visit(this);
}
}
class ObjectElementStruct
{
List<IElement> aList=new ArrayList<IElement>();
public void add(IElement iElement)
{
aList.add(iElement);
}
public void accept(IVisitor iVisitor)
{
for(IElement iElement:aList)
iElement.accept(iVisitor);
}
}
public class VisitorPatternTest
{
public static void main(String[] args)
{
ObjectElementStruct ob=new ObjectElementStruct();
ob.add(new Banana());
ob.add(new Rice());
ob.add(new Apple());
ob.accept(new Human());
ob.accept(new Monkey());
}
}
java中23种设计模式之16-访问者模式（visitor pattern）
原文：http://www.cnblogs.com/wudymand/p/4388336.html