命令模式也属于行为型模式，它将一个请求封装为一个对象，让用户使用不同的请求把客户端参数化。一般有三种角色：1、received 真正的命令执行对象 2、Command 各种命令3、invoker 使用命令对象的入口。
通过添加命令接口将请求者和执行者解耦。
简单实现：
命令接口：
public interface Command {
void execute();
}
命令实际执行者：
public class Receiver {
public void action1(){
System.out.println("action1");
}
public void action2(){
System.out.println("action2");
}
}
定义各种实际命令
public class ConcreteCommand1 implements Command{
private Receiver receiver;
public ConcreteCommand1(Receiver receive){
this.receiver = receive;
}
@Override
public void execute() {
receiver.action1();
}
}
public class ConcreteCommand2 implements Command{
private Receiver receiver;
public ConcreteCommand2(Receiver receive){
this.receiver = receive;
}
@Override
public void execute() {
receiver.action2();
}
}
命令调用者
public class Invoker {
private ArrayList<Command> list = new ArrayList<>();
public void setCommand(Command command){
list.add(command);
}
public void execute(){
for (Command command : list)
command.execute();
}
}
测试类
public static void main(String[] args) {
Invoker invoker = new Invoker();
Receiver receiver = new Receiver();
invoker.setCommand(new ConcreteCommand1(receiver));
invoker.setCommand(new ConcreteCommand2(receiver));
invoker.setCommand(new ConcreteCommand1(receiver));
invoker.execute();
}
