设计模式——状态模式

小咪咪 2022-12-29 09:14 107阅读 0赞

## 设计模式——状态模式 ##

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dlaXhpbl80Mzk0NTQ3MQ_size_16_color_FFFFFF_t_70_pic_center]  
状态模式（State）,当一个对象的内在状态改变时允许改变其行为，这个对象看起来像是改变了其类。、

abstract class State
        {
        
            public abstract void Handle(Context context);
        }
    
        class ConcreteStateA : State
        {
        
            public override void Handle(Context context)//设置ConcreteStateA的下一状态是ConcreteStateB
            {
        
                context.State = new ConcreteStateB();
            }
        }
    
        class ConcreteStateB : State
        {
        
            public override void Handle(Context context)//设置ConcreteStateA的下一状态是ConcreteStateB
            {
        
                context.State = new ConcreteStateA();
            }
        }
        class Context
        {
        
            private State state;
    
            public Context(State state)
            {
        
                this.state = state;
            }
    
            public State State
            {
        
                get {
         return state; }
                set
                {
        
                    state = value;
                    Console.WriteLine("当前状态：" + state.GetType().Name);
                }
            }
    
            public void Request()//对请求做处理，并设置下一状态
            {
        
                state.Handle(this);
            }
        }
             static void Main(string[] args)
            {
        
                Context c = new Context(new ConcreteStateA());//设置Context的初始状态为ConcreteStateA
                c.Request();//不断的请求，同时更改状态
                c.Request();
                c.Request();
                c.Request();
            }

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