命令模式（Command），将一个请求封装为一个对象，从而使你可用不同的请求对客户进行参数化；对请求排队或记录请求日志，以及支持可撤销的操作。[DP]

// 命令接口
interface Command {void execute();
}// 具体命令类，实现了命令接口
class ConcreteCommand implements Command {private Receiver receiver;public ConcreteCommand(Receiver receiver) {this.receiver = receiver;}@Overridepublic void execute() {receiver.action();}
}// 接收者类，知道如何执行请求
class Receiver {public void action() {System.out.println("Receiver: 执行操作");}
}// 调用者类，负责发送命令
class Invoker {private Command command;public Invoker(Command command) {this.command = command;}public void setCommand(Command command) {this.command = command;}public void executeCommand() {command.execute();}
}// 客户端代码
public class Client {public static void main(String[] args) {// 创建接收者Receiver receiver = new Receiver();// 创建具体命令对象，并将接收者传递给它Command command = new ConcreteCommand(receiver);// 创建调用者，并将命令传递给它Invoker invoker = new Invoker(command);// 通过调用者执行命令invoker.executeCommand();}
}