【设计模式】一文快速搞懂状态模式

class Light {

    // 电灯状态
    private boolean isOn;

    public Light() {
     // 初始状态为关闭
        this.isOn = false; 
    }

   // 不同状态按下开关逻辑
    public void toggleSwitch() {
        if (isOn) {
        // 开启状态按下开关，状态变为关闭
            System.out.println("Light is turned OFF");
            isOn = false;
        } else {
        // 关闭状态按下开关，状态变为开启
            System.out.println("Light is turned ON");
            isOn = true;
        }
    }
}

class Light {
    private boolean isOn;
    // 新增调光Dim状态
    private boolean isDim;

    public Light() {
        this.isOn = false; // 初始状态为关
        this.isDim = false; // 初始不是调光状态
    }

    public void toggleSwitch() {

       // 增加状态后修改状态转换逻辑
        if (isOn) {
            if (isDim) {
                System.out.println("Light is turned OFF");
                isOn = false;
                isDim = false;
            } else {
                System.out.println("Light is turned Dim");
                isDim = true;
            }
        } else {
            System.out.println("Light is turned ON");
            isOn = true;
        }
    }
}

// 状态接口
interface State {
    void toggleSwitch(Light light);
}

// 具体状态类：灯关闭状态
class OffState implements State {
    @Override
    public void toggleSwitch(Light light) {
        System.out.println("Light is turned ON");
        light.setState(new OnState());
    }
}

// 具体状态类：灯打开状态
class OnState implements State {
    @Override
    public void toggleSwitch(Light light) {
        System.out.println("Light is turned Dim");
        light.setState(new DimState());
    }
}

// 具体状态类：灯调光状态
class DimState implements State {
    @Override
    public void toggleSwitch(Light light) {
        System.out.println("Light is turned OFF");
        light.setState(new OffState());
    }
}

// 环境类，电灯
class Light {
    private State state;

    public Light() {
        // 初始状态为关
        this.state = new OffState();
    }

    public void setState(State state) {
        this.state = state;
    }

    public void toggleSwitch() {
        state.toggleSwitch(this);
    }
}