23种设计模式-命令模式

1.命令模式

将一个请求封装为一个对象，从而使你可用不同的请求对客户进行参数化；对请求排队或记录请求日志，以及支持可取消的操作。

优缺点

优点：

降低耦合 扩展性高

缺点：

增加复杂

使用场景

实现方式

抽象命令类：Command.java

/**
 * Command命令接口，为所有的命令声明一个接口。所有的命令都应该实现它
 */
public interface Command {
	public void execute();
}

电视机类：Television.java

public class Television {
	public void open(){
		System.out.println("打开电视机......");
	}
	
	public void close(){
		System.out.println("关闭电视机......");		
	}
	
	public void changeChannel(){
		
		System.out.println("切换电视频道......");
	}
}

遥控器类：Controller.java

public class Controller {
	private Command openTVCommand;
	private Command closeTVCommand;
	private Command changeChannelCommand;
	
	public Controller(Command openTvCommand,Command closeTvCommand,Command changeChannelCommand){
		this.openTVCommand = openTvCommand;
		this.closeTVCommand = closeTvCommand;
		this.changeChannelCommand = changeChannelCommand;
	}
	
	/**
	 * 打开电视剧
	 */
	public void open(){
		openTVCommand.execute();
	}
	
	/**
	 * 关闭电视机
	 */
	public void close(){
		closeTVCommand.execute();
	}
	
	/**
	 * 换频道
	 */
	public void change(){
		changeChannelCommand.execute();
	}
}

遥控器的三个按钮：

public class OpenTvCommand implements Command{
	private Television tv;
	
	public OpenTvCommand(Television tv){
		this.tv = tv;
	}
	
	public void execute() {
		tv.open();
	}
}

public class ChangeChannelCommand implements Command{
	private Television tv;
	
	public ChangeChannelCommand(Television tv){
		this.tv = tv;
	}
	
	public void execute() {
		tv.changeChannel();
	}
}

public class CloseTvCommand implements Command{
	private Television tv;
	
	public CloseTvCommand(Television tv){
		this.tv = tv;
	}
	
	public void execute() {
		tv.close();
	}
}

测试类

public class Client {
		public static void main(String a[])
		{
			Television tv = new Television();
                        Command openCommand,closeCommand,changeCommand;
			
			openCommand = new OpenTvCommand(tv);
			closeCommand = new CloseTvCommand(tv);
			changeCommand = new ChangeChannelCommand(tv);
			
			Controller control = new Controller(openCommand,closeCommand,changeCommand);
			
			control.open();           //打开电视机
			control.change();         //换频道
			control.close();          //关闭电视机
		}
}

参考博客：https://blog.csdn.net/a745233700/article/details/83713445