http://www.verejava.com/?id=16999202350980

package com.visit.theory;import java.util.ArrayList;public class Test
{public static void main(String[] args){ObjectStructure o = new ObjectStructure();  //依赖于ObjectStructure   //实例化具体元素   o.attach(new Man());     o.attach(new Woman());   //当成功时不同元素的不同反映   Visitor success = new Success();           //依赖于抽象的Visitor接口   o.display(success);   //当恋爱时的不同反映   Visitor amativeness = new Love();          //依赖于抽象的Visitor接口   o.display(amativeness);        }
}package com.visit.theory;public interface Visitor
{public void visit(Man man);     public void visit(Woman w);   }package com.visit.theory;public interface Person
{void accept(Visitor visitor);
}package com.visit.theory;public class Woman implements Person {   // 先对visitor进行类型转换，再执行visit方法，因为Visitor接口已经没有声明任何抽象方法了   public void accept(Visitor visitor) {   visitor.visit(this);}
}   package com.visit.theory;public class Man implements Person {   // 先对visitor进行类型转换，再执行visit方法，因为Visitor接口已经没有声明任何抽象方法了   public void accept(Visitor visitor) {   visitor.visit(this);}
}   package com.visit.theory;public class Success implements Visitor{   public void visit(Man man) {   System.out.println("当男人成功时，背后多半有一个伟大的女人");   }   public void visit(Woman girl) {   System.out.println("当女人成功时，背后大多有一个不成功的男人");   }
}   package com.visit.theory;public class Love implements Visitor{   public void visit(Man man) {   System.out.println("当男人恋爱时，凡事不懂也装懂");   }   public void visit(Woman girl) {   System.out.println("当女人恋爱时，遇事懂也装不懂");   }   }   package com.visit.theory;import java.util.ArrayList;
import java.util.List;public class ObjectStructure
{private List<Person> elements = new ArrayList<Person>();   public void attach(Person element){   elements.add(element);   }   public void detach(Person element){   elements.remove(elements);   }   //遍历各种具体元素并执行他们的accept方法   public void display(Visitor visitor){   for(Person p:elements){   p.accept(visitor);   }   }
}