client包:
package day23.client; import day23.test.IMessageBoard; import day23.test.MessageBorad; import day23.test.MessageBoradDecoator; import day23.test.MessageBoradExtend; public class Client { public static void main(String[] args) { Client c=new Client(); //IMessageBoard messageBoard=new MessageBorad(); //方法一:通过继承实现功能的扩张,若拓展功能繁多,会有很多子类,增加系统的复杂性 //IMessageBoard messageBoard=new MessageBoradExtend(); //方法二:通过装饰对象。需由用户动态决定加入的方式和时机。Decorator提供了“即插即用” //的方法,在运行期间决定何时增加何种功能。 MessageBorad m=new MessageBorad();//不可变的类 IMessageBoard messageBoard=new MessageBoradDecoator(m); c.test(messageBoard); } public void test(IMessageBoard messageBoard) { System.out.println("messageBoard= "+messageBoard); String content=messageBoard.filter(); System.out.println("客户端content= "+content); } }
test包:
1.IMessageBoard:
package day23.test; //抽象构件角色(Component) public interface IMessageBoard { public String filter(); }
2. MessageBorad:
package day23.test; //具体构件角色(Concrete Component) public class MessageBorad implements IMessageBoard { public String filter() { return "你喜欢战争吗"; } }
3.MessageBoradDecoator:
package day23.test; //具体装饰构件角色(Concrete Decorator) //实现 抽象构件角色的接口,还需要一个具体构件角色的类的对象 public class MessageBoradDecoator implements IMessageBoard { private IMessageBoard messageBoard; public MessageBoradDecoator(IMessageBoard messageBoard) { this.messageBoard=messageBoard; } public String filter() { String content=messageBoard.filter(); return content.replaceAll("战争", "和平"); } }
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//方法一:通过继承处理 package day23.test; public class MessageBoradExtend extends MessageBorad { @Override public String filter() { String content=super.filter(); System.out.println("MessageBoradExtend "+content); return content.replaceAll("战争", "和平"); } }