需求:现有一个遥控器,有七个可编程的插槽,每个插槽都对应开关按钮,遥控器还具备一个整体的撤销按钮。
可控装置:电灯、风扇、热水器、音响设备和其它类似的可控制装备。要求能够控制目前的装置和任何未来可能出现的装置。
我们把这个过程想象成餐厅吃饭的过程:顾客根据菜单点单,然后将订单给服务员,服务员将订单放到厨房柜台上,厨师拿到订单进行执行,制作出美味的饭菜。
在这里,遥控器就是一个远程控制,它掌握一系列的命令接口,当我们按下遥控器按钮时,发出相应的命令进行执行,相应的命令对象接收到执行命令后发送命令给具体执行者,具体执行者收到命令并执行相应的行文。这就达到了请求者与具体执行者解耦的目的。
首先把问题简化,假设我们只有一个遥控器,它只有一个按钮和对应的插槽,可以控制一个装置。
设计图如下:
实现代码如下:
远程控制类SimpleRemoteControl :
public class SimpleRemoteControl {
Command slot;
public SimpleRemoteControl(){}
public Command getSlot() {
return slot;
}
public void setSlot(Command slot) {
this.slot = slot;
}
public void buttonWasPressed()
{
slot.execute();
}
}
命令接口Command:
public interface Command {
public void execute();
}
具体命令类:
灯泡开命令类LightOnCommand:
public class LightOnCommand implements Command{
Light light;
public LightOnCommand(Light light)
{
this.light=light;
}
@Override
public void execute() {
// TODO Auto-generated method stub
light.on();
}
}
灯泡关命令类:
public class LightOffCommand implements Command{
Light light;
public LightOffCommand(Light light)
{
this.light=light;
}
@Override
public void execute() {
// TODO Auto-generated method stub
light.off();
}
}
车门开命令类:
public class GargeDoorOpenCommand implements Command{
GargeDoor gargeDoor;
public GargeDoorOpenCommand(GargeDoor gargeDoor)
{
this.gargeDoor=gargeDoor;
}
@Override
public void execute() {
// TODO Auto-generated method stub
gargeDoor.open();
}
}
车门关命令类:
public class GargeDoorCloseCommand implements Command{
GargeDoor gargeDoor;
public GargeDoorCloseCommand(GargeDoor gargeDoor)
{
this.gargeDoor=gargeDoor;
}
@Override
public void execute() {
// TODO Auto-generated method stub
gargeDoor.close();
}
}
最后接收执行者类:
灯泡:
public class Light {
public void on()
{
System.out.println("light is on");
}
public void off()
{
System.out.println("light is close");
}
}
车门:
public class GargeDoor {
public void open()
{
System.out.println("door is open");
}
public void close()
{
System.out.println("door is close");
}
}
测试类:
public class RemoteControlTest {
public static void main(String[] args)
{
SimpleRemoteControl remote=new SimpleRemoteControl();
Light light=new Light();
LightOnCommand lightOn=new LightOnCommand(light);
remote.setSlot(lightOn);
remote.buttonWasPressed();
GargeDoor gargeDoor=new GargeDoor();
GargeDoorOpenCommand gargeDoorOpen=new GargeDoorOpenCommand(gargeDoor);
remote.setSlot(gargeDoorOpen);
remote.buttonWasPressed();
}
}
命令模式第一篇