设计模式之 命令模式

命令模式将命令调用者与命令执行者解耦，有效降低系统的耦合度。同时，由于命令调用者和命令执行者进行了解耦，所以增加和删除命令变得非常方便。

（1）定义Command接口

public interface Command{
    public void exe(String command);
}

（2）定义Command实现类

public class ConcreteCommand implements Command{
    private Receiver receiver;
    public ConcreteCommand(Receiver receiver){
        this.receiver = receiver;
    }
    
    @Override
    public void exe(String command){
        receiver.action(command);
    }
}

（3）定义命令调用者

public class Invoker{
    private final static Log logger = LogFactory.getLog(this.getClass());
    private Command command;
    public Invoker(Command command){
        this.command = command;
    }
    public void action(String commandMessage){
        logger.info("command sending...");
        command.exe(commandMessage);
    }
}

（4）定义命令接收者

public class Receiver{
    private final static Log logger = LogFactory.getLog(this.getClass());
    public void action(String command){
        logger.info("command received");
    }
}

（5）使用命令模式

public static void main(String args){
    Receiver receiver = new Receiver();
    Command cmd = new ConcreteCommand(receiver);
    Invoker invoker = new Invoker(cmd);
    invoker.action("cmd1");
}

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