public class NumberMachine {
private NumberManager commanManager;
private NumberManager expressManager;
private NumberManager vipManager;
public NumberManager getCommanManager() {
        return commanManager;
}
public NumberManager getExpressManager() {
        return expressManager;
}
public NumberManager getVipManager() {
        return vipManager;
}
//单例模式的代码解释
private NumberMachine(){
       
}
public static NumberMachine getInstance(){
        return Instance;
}
public static NumberMachine Instance=new NumberMachine();
}

只能产生一个实例供外部反问，必须自己创建唯一实例，必须给其他所有对象提供这一实例