【体系结构（设计模式）】单一职责原则

概念
一个类应该只负责一项职责。
如果类A负责两个不同职责：职责1、职责2，当职责1需求变更而改变A时，可能造成职责2执行错误，所以需要将A的粒度分解为A1、A2

注意事项和细节

1、降低类的复杂度，一个类只负责一项职责

2、提高类的可读性、可维护性

3、降低变更引起的风险

4、逻辑足够简单，可以在代码级别违反单一职责SingleResponsibility1；
方法数量足够少，可以在方法级别保持单一职责SingleResponsibility2

package com.atguigu.principle.singleresponsibility;

public class SingleResponsibility1 {

    public static void main(String[] args){
        Vehicle vehicle = new Vehicle();
        vehicle.run("摩托车");
        vehicle.run("汽车");
        vehicle.run("飞机");
    }

}

//交通工具类


class Vehicle{
    public void run(String vehicle){
        System.out.println(vehicle + "在公路上……");
    }
}

package com.atguigu.principle.singleresponsibility;

public class SingleResponsibility2 {
    public static void main(String[] args) {
        RoadVehicle roadvehicle = new RoadVehicle();
        roadvehicle.run("摩托车");
        AirVehicle airVehicle = new AirVehicle();
        airVehicle.run("飞机");

    }
}


class RoadVehicle{
    public void run(String vehicle){
        System.out.println(vehicle + "在公路上……");
    }
}
class AirVehicle{
    public void run(String vehicle){
        System.out.println(vehicle + "在空中……");
    }
}
class WaterVehicle{
    public void run(String vehicle){
        System.out.println(vehicle + "在水里……");
    }
}

package com.atguigu.principle.singleresponsibility;

public class SingleResponsibility3 {
    public static void main(String[] args) {
        Vehicle2 vehicle = new Vehicle2();
        vehicle.run("摩托车");
        vehicle.run("汽车");
        vehicle.runAir("飞机");
    }
}


class Vehicle2{
    public void run(String vehicle){
        System.out.println(vehicle + "在公路上……");
    }
    public void runAir(String vehicle){
        System.out.println(vehicle + "在空中……");
    }
    public void runWater(String vehicle){
        System.out.println(vehicle + "在水里……");
    }
}