命令模式（Command）

命令模式的目的就是将命令的发出者和执行者之间解耦。
我们以司令员给士兵发布指令执行为例：

//命令接口类
public interface Command
{
    void action();
}

public class MyCommand implements Command
{
    private Receiver receiver;
    public MyCommand(Receiver receiver)
    {
        this.receiver = receiver;
    }
    @override
    public void exe()
    {
        receiver.action();
    }
}

//士兵
public class Receiver
{
    public void action()
    {
        System.out.println("command received");
    }
}

//司令官
public class Invoker
{
    private Command command;
    public Invoker(Command command)
    {
        this.command = command;
    }
    public void action()
    {
        command.exe();
    }
}
//测试类
public class Test
{
    public static void main(String[] args)
    {
        Receiver receiver= new Receiver();
        Command command = new MyCommand(receiver);
        Invoker invoker = new Invoker(command);
        invoker.action();
    }
}

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