命令模式(command pattern)的定义: 命令模式将请求(命令)封装为一个对象,这样可以使用不同的请求参数化其他对象(将不 同请求依赖注入到其他对象),并且能够支持请求(命令)的排队执行、记录日志、撤销等 (附加控制)功能。
命令模式的核心是将指令信息封装成一个对象,并将此对象作为参数发送给接收方去执行,达到使命令的请求与执行方解耦,双方只通过传递各种命令对象来完成任务.
/**
* 订单类
**/
public class Order {
private int diningTable; //餐桌号码
//存储菜名与份数
private Map<String,Integer> foodMenu = new HashMap<>();
public int getDiningTable() {
return diningTable;
}
public void setDiningTable(int diningTable) {
this.diningTable = diningTable;
}
public Map<String, Integer> getFoodMenu() {
return foodMenu;
}
public void setFoodDic(Map<String, Integer> foodMenu) {
this.foodMenu = foodMenu;
}
}
/**
* 厨师类 -> Receiver角色
**/
public class Chef {
public void makeFood(int num,String foodName){
System.out.println(num + "份," + foodName);
}
}
/**
* 抽象命令接口
**/
public interface Command {
void execute(); //只需要定义一个统一的执行方法
}
/**
* 具体命令
**/
public class OrderCommand implements Command {
//持有接收者对象
private Chef receiver;
private Order order;
public OrderCommand(Chef receiver, Order order) {
this.receiver = receiver;
this.order = order;
}
@Override
public void execute() {
System.out.println(order.getDiningTable() + "桌的订单: ");
Set<String> keys = order.getFoodMenu().keySet();
for (String key : keys) {
receiver.makeFood(order.getFoodMenu().get(key),key);
}
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(order.getDiningTable() + "桌的菜已上齐.");
}
}
/**
* 服务员-> Invoker调用者
**/
public class Waiter {
//可以持有很多的命令对象
private ArrayList<Command> commands;
public Waiter() {
commands = new ArrayList();
}
public Waiter(ArrayList<Command> commands) {
this.commands = commands;
}
public void setCommands(Command command) {
commands.add(command);
}
//发出命令 ,指挥厨师工作
public void orderUp(){
System.out.println("服务员: 叮咚,有新的订单,请厨师开始制作......");
for (Command cmd : commands) {
if(cmd != null){
cmd.execute();
}
}
}
}
public class Client {
public static void main(String[] args) {
Order order1 = new Order();
order1.setDiningTable(1);
order1.getFoodMenu().put("鲍鱼炒饭",1);
order1.getFoodMenu().put("茅台迎宾",1);
Order order2 = new Order();
order2.setDiningTable(3);
order2.getFoodMenu().put("海参炒面",1);
order2.getFoodMenu().put("五粮液",1);
//创建接收者
Chef receiver = new Chef();
//将订单和接收者封装成命令对象
OrderCommand cmd1 = new OrderCommand(receiver,order1);
OrderCommand cmd2 = new OrderCommand(receiver,order2);
//创建调用者
Waiter invoke = new Waiter();
invoke.setCommands(cmd1);
invoke.setCommands(cmd2);
//将订单发送到后厨
invoke.orderUp();
}
}