设计模式-命令模式

命令模式是一个高内聚的模式。
	Encapsulate a request as an object, thereby letting you parameterize clients with different requests,
	queue or log requests,and support undoable operations.
	将一个请求封装成一个对象，从而让你使用不同的请求把客户端参数化，对请求排队或者记录请求日志，可以提供
	命令的撤销和恢复功能。
	
	public abstract class Reciver {
	
		public abstract void doSomething();

	}
	public class ConcreteReciver1 extends Reciver {

		@Override
		public void doSomething() {
			// TODO Auto-generated method stub

		}

	}
	public abstract class Command {

		public abstract void execute();
		
	}	
	
	public class ConcreteCommand1 extends Command {

		private Reciver reciver;
		
		public ConcreteCommand1(Reciver reciver) {
			this.reciver = reciver;
		}
		
		@Override
		public void execute() {
			this.reciver.doSomething();
		}

	}	
	public class ConcreteCommand2 extends Command {

		private Reciver reciver;
		
		public ConcreteCommand2(Reciver reciver) {
			this.reciver = reciver;
		}
		
		@Override
		public void execute() {
			this.reciver.doSomething();
		}

	}	
	public class Invoker {

		private Command command;
		
		public void setCommand(Command command) {
			this.command = command;
		}
		
		public void action() {
			this.command.execute();
		}
	}
	
	public class Client {

		public static void main(String[] args) {
			
			Invoker invoker = new Invoker();
			Reciver reciver = new ConcreteReciver1();
			
			Command command = new ConcreteCommand1(reciver);
			invoker.setCommand(command);
			invoker.action();
			
		}

	}
	
	命令模式的优点
	（1）类间解耦 （2）可扩展性 （3）结合其他模式
	
	命令模式的使用场景
	GUI的开发，DOS模拟，出发-反馈机制