12_状态模式

package com.Higgin.State;

/**
 * 水的状态 
 */
interface WaterState{
    public void printState();
}

/**
 * 固态水 
 */
class SolidWaterState implements WaterState{
    @Override
    public void printState() {
        System.out.println("0°C以下，水是固态的...");
    }
}
/**
 * 液态水 
 */
class LiquidWaterState implements WaterState{
    @Override
    public void printState() {
        System.out.println("0°C~100°C之间，水是液态的...");
    }
}
/**
 * 气态水 
 */
class GasWaterState implements WaterState{
    @Override
    public void printState() {
        System.out.println("100°C以上，水是气态的...");
    }
}
/**
 * 水状态的上下文类 
 */
class WaterContext{
    private WaterState waterState;
    public void setState(int temp){
        if(temp<=0){         //温度小于等于0°C，初始化为固态
            waterState=new SolidWaterState();
        }else if(temp>=100){  //温度在0~100°C之间，初始化为液态
            waterState=new GasWaterState();
        }else{                //温度在100°C及以上，初始化为气态
            waterState=new LiquidWaterState();
        }
    }
    
    //得到当前 水的具体状态类
    public WaterState getState(){
        return this.waterState;
    }
}
public class TestState {

    public static void main(String[] args) {
        WaterContext wc=new WaterContext();
        wc.setState(18);
        WaterState ws=wc.getState();
        ws.printState();
    }
}