策略模式

//通用接口
public interface IStrate {

public void operate();

}

//第一步
public class One implements IStrate {

@Override
public void operate() {

System.out.println("第一步开始");
}

}

//第二步
public class Two implements IStrate {

@Override
public void operate() {
     System.out.println("第二步开始");

}

}


public class Context {


   private  IStrate  istrate;
  
   public Context(IStrate  istrate){
   this.istrate=istrate;
   }
  
   public void operate(){
   this.istrate.operate();
   }
}



public class Client {

public static void main(String[] args) {
    Context context;
   
    System.out.println("拆第一个妙计");
    context = new Context(new One());
    context.operate();
   
    System.out.println("拆第二个妙计");
    context = new Context(new Two());
    context.operate();
   
    System.out.println("拆第三个妙计");
    context = new Context(new Three());
    context.operate();
   
    }
}