Java设计模式：命令模式（动作模式/事物模式）

约定不等于承诺〃 2023-10-18 17:28 74阅读 0赞

参考附录文章1。再写一个例子说明命令模式。

/**
     * 命令。比如发布的一个命令（进攻，撤退）。
     * 
     * @author zhangfly
     *
     */
    public abstract class Command {
    	public abstract void execute();
    }

/**
     * 抽象的命令接受者。比如solder。
     * 
     * @author zhangfly
     *
     */
    public abstract class Receiver {
    	public abstract void action();
    }

import java.util.ArrayList;
    
    public class ConcreteCommand extends Command {
    	private Receiver receiver;
    	private ArrayList<Receiver> receivers;
    
    	public ConcreteCommand(Receiver receiver) {
    		this.receiver = receiver;
    	}
    
    	public ConcreteCommand(ArrayList<Receiver> receivers) {
    		this.receivers = receivers;
    	}
    
    	public void execute() {
    		if (receiver != null) {
    			receiver.action();
    		}
    
    		if (receivers != null) {
    			for (Receiver r : receivers) {
    				r.action();
    			}
    		}
    	}
    }

/**
     * 具体的执行命令者。
     * 
     * @author zhangfly
     *
     */
    public class MyReceiver extends Receiver {
    	private String tag = "";
    
    	public MyReceiver(String tag) {
    		this.tag = tag;
    	}
    
    	@Override
    	public void action() {
    		System.out.println("MyReceiver action" + getTag());
    	}
    
    	public String getTag() {
    		return tag;
    	}
    }

/**
     * 命令调用者（发布者）。比如司令长官。
     * 
     * @author zhangfly
     *
     */
    public class Invoker {
    	private Command command;
    
    	public Invoker(Command command) {
    		this.command = command;
    	}
    
    	//调用命令类的execute()。
    	public void call() {
    		command.execute();
    	}
    }

import java.util.ArrayList;
    
    public class Test {
    	public Test() {
    		// 单个命令执行者。
    		Receiver receiver1 = new MyReceiver("单个士兵");// 士兵。
    		Command command1 = new ConcreteCommand(receiver1);// 一个命令。
    		Invoker invoker1 = new Invoker(command1);// 司令发布命令。
    		invoker1.call();
    
    		// 一批命令执行者。
    		ArrayList<Receiver> receivers = new ArrayList<Receiver>();
    		for (int i = 0; i < 5; i++) {
    			Receiver r = new MyReceiver("士兵" + i);
    			receivers.add(r);
    		}
    
    		Command command2 = new ConcreteCommand(receivers);
    		Invoker invoker2 = new Invoker(command2);
    		invoker2.call();
    	}
    
    	public static void main(String[] args) {
    		new Test();
    	}
    }

输出：

MyReceiver action单个士兵
    MyReceiver action士兵0
    MyReceiver action士兵1
    MyReceiver action士兵2
    MyReceiver action士兵3
    MyReceiver action士兵4

附：

1，《Java设计模式：命令模式》

[https://blog.csdn.net/zhangphil/article/details/88740160][https_blog.csdn.net_zhangphil_article_details_88740160]

[https_blog.csdn.net_zhangphil_article_details_88740160]: https://blog.csdn.net/zhangphil/article/details/88740160