Java设计模式 - 状态模式

Love The Way You Lie 2022-11-25 00:40 176阅读 0赞

**目录**

状态模式：

状态优点：

状态模式应用：

状态实例：

类图：

示例：

代码：

上述代码 GitHub 地址：https://github.com/baicun/designPatterns

--------------------

# [状态模式：][Link 1] #

能根据内部状态的变化，改变对象的行为，看起来好像修改了类

# [状态优点：][Link 2] #

特定状态相关的行为局部化，把不同的状态隔离，耦合性低

# [状态模式应用：][Link 3] #

一个对象存在多个状态（不同状态下行为不同），且状态可相互转换。

# [状态实例：][Link 4] #

## 类图： ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NzZG5fMDkxMQ_size_16_color_FFFFFF_t_70][]

## 示例： ##

糖果机有如下几种状态：待机、投币、转动把手、滑落糖果、待机。不同状态绑定不同的行为，如此使用状态模式解决。

## 代码： ##

糖果机-CandyMachine.java

public class CandyMachine {
    
    	State mSoldOutState;
    	State mOnReadyState;
    	State mHasCoin;
    	State mSoldState;
    	State mWinnerState;
    	private State state;
    	private int count = 0;
    
    	public CandyMachine(int count) {
    		this.count = count;
    		mSoldOutState = new SoldOutState(this);
    		mOnReadyState = new OnReadyState(this);
    		mHasCoin = new HasCoin(this);
    		mSoldState = new SoldState(this);
    		mWinnerState = new WinnerState(this);
    		if (count > 0) {
    			state = mOnReadyState;
    		} else {
    			state = mSoldOutState;
    		}
    	}
    
    	public void setState(State state) {
    		this.state = state;
    	}
    
    	public void insertCoin() {
    		state.insertCoin();
    	}
    
    	public void returnCoin() {
    		state.returnCoin();
    	}
    
    	public void turnCrank() {
    		state.turnCrank();
    		state.dispense();
    	}
    
    	void releaseCandy() {
    
    		if (count > 0) {
    			count = count - 1;
    			System.out.println("a candy rolling out!");
    		}
    
    	}
    
    	public int getCount() {
    		return count;
    	}
    
    	public void printstate() {
    		state.printstate();
    	}
    }

状态接口-State.java

public interface State {
    	//塞入硬币
    	public void insertCoin();
    	//返回硬币
    	public void returnCoin();
    	//转动把手
    	public void turnCrank();
    	//分发
    	public void dispense();
    	//当前状态
    	public void printstate();
    }

待机状态-OnReadyState.java

public class OnReadyState implements State {
    	private CandyMachine mCandyMachine;
    	public OnReadyState(CandyMachine mCandyMachine)
    	{
    		this.mCandyMachine=mCandyMachine;
    	}
    
    	@Override
    	public void insertCoin() {
    		// TODO Auto-generated method stub
    		System.out.println("you have inserted a coin,next,please turn crank!");
    		mCandyMachine.setState(mCandyMachine.mHasCoin);
    	}
    
    	@Override
    	public void returnCoin() {
    		// TODO Auto-generated method stub
    		System.out.println("you haven't inserted a coin yet!");
    		
    	}
    
    	@Override
    	public void turnCrank() {
    		// TODO Auto-generated method stub
    		System.out.println("you turned,but you haven't inserted a coin!");
    		
    	}
    
    	@Override
    	public void dispense() {
    		// TODO Auto-generated method stub
    
    	}
    
    	@Override
    	public void printstate() {
    		// TODO Auto-generated method stub
    		System.out.println("***OnReadyState***");
    		
    	}
    
    }

塞入硬币-HasCoin.java

public class HasCoin implements State {
    	private CandyMachine mCandyMachine;
    
    	public HasCoin(CandyMachine mCandyMachine) {
    		this.mCandyMachine = mCandyMachine;
    	}
    
    	@Override
    	public void insertCoin() {
    		// TODO Auto-generated method stub
    		System.out.println("you can't insert another coin!");
    
    	}
    
    	@Override
    	public void returnCoin() {
    		// TODO Auto-generated method stub
    		System.out.println("coin return!");
    		mCandyMachine.setState(mCandyMachine.mOnReadyState);
    	}
    
    	@Override
    	public void turnCrank() {
    		// TODO Auto-generated method stub
    		System.out.println("crank turn...!");
    		Random ranwinner=new Random();
    		int winner=ranwinner.nextInt(10);
    		if(winner==0)
    		{
    			mCandyMachine.setState(mCandyMachine.mWinnerState);
    
    		}else
    		{
    			mCandyMachine.setState(mCandyMachine.mSoldState);
    
    		}
    		
    	}
    
    	@Override
    	public void dispense() {
    	}
    
    	@Override
    	public void printstate() {
    		// TODO Auto-generated method stub
    		System.out.println("***HasCoin***");
    
    	}
    
    }

测试类：

public class MainTest {
    	public static void main(String[] args) {
    		CandyMachine mCandyMachine = new CandyMachine(6);
    
    		mCandyMachine.printstate();
    
    		mCandyMachine.insertCoin();
    		mCandyMachine.printstate();
    
    		mCandyMachine.turnCrank();
    
    		mCandyMachine.printstate();
    
    		mCandyMachine.insertCoin();
    		mCandyMachine.printstate();
    
    		mCandyMachine.turnCrank();
    
    		mCandyMachine.printstate();
    	}
    }

# [上述代码 GitHub 地址：https://github.com/baicun/designPatterns][GitHub _https_github.com_baicun_designPatterns] #

[Link 1]: https://blog.csdn.net/csdn_0911/article/details/107833281#%E4%BB%A3%E7%90%86%E6%A8%A1%E5%BC%8F%EF%BC%9A-toc-toc-toc-toc-toc-toc-toc-toc-toc
[Link 2]: https://blog.csdn.net/csdn_0911/article/details/107833281#%E7%BB%84%E5%90%88%E4%BC%98%E7%82%B9%EF%BC%9A
[Link 3]: https://blog.csdn.net/csdn_0911/article/details/107833281#%E7%BB%84%E5%90%88%E6%A8%A1%E5%BC%8F%E5%BA%94%E7%94%A8%EF%BC%9A
[Link 4]: https://blog.csdn.net/csdn_0911/article/details/107833281#%E7%BB%84%E5%90%88%E5%AE%9E%E4%BE%8B%EF%BC%9A
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L2NzZG5fMDkxMQ_size_16_color_FFFFFF_t_70]: /images/20221124/52c38f4ad6844124a449135e7c98c034.png
[GitHub _https_github.com_baicun_designPatterns]: https://blog.csdn.net/csdn_0911/article/details/107833281#%E4%B8%8A%E8%BF%B0%E4%BB%A3%E7%A0%81%20GitHub%20%E5%9C%B0%E5%9D%80%EF%BC%9Ahttps%3A%2F%2Fgithub.com%2Fbaicun%2FdesignPatterns