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描述

命令模式是一种体现高内聚的行为模式。
将整个请求封装成一个命令对象，由这个命令对象完成所需业务调用。
命令对象封装了该命令需要的所有逻辑，不需要调用方关注内部细节。

基本使用

• 定义抽象命令（所有命令都基于这个抽象命令定义）

public abstract class AbstractCommand {abstract void execute();
}

• 定义命令对象内要实际调用的业务对象

public interface IReceiver {void action();
}public class ReceiverA implements IReceiver {@Overridepublic void action() {System.out.println("ReceiverA action ....");}
}public class ReceiverB implements IReceiver {@Overridepublic void action() {System.out.println("ReceiverB action ....");}
}

• 定义两个具体的命令

public class CommandA extends AbstractCommand{private IReceiver receiver;public CommandA(IReceiver receiver) {this.receiver = receiver;}@Overridevoid execute() {System.out.println("commandA....");receiver.action();}
}public class CommandAB extends AbstractCommand{private IReceiver[] receivers;public CommandAB(IReceiver... receivers) {this.receivers = receivers;}@Overridevoid execute() {System.out.println("commandA....");for (IReceiver receiver : receivers) {receiver.action();}}
}

使用

public class Sample {public static void main(String[] args) {IReceiver receiverA = new ReceiverA();IReceiver receiverB = new ReceiverB();AbstractCommand command = new CommandA(receiverA);command.execute();AbstractCommand commandAb = new CommandAB(receiverA, receiverB);commandAb.execute();}
}