.Net行为型设计模式之状态模式（State）

public static void Main(String[] args)
{
    //订单
    Order order = new Order();
    order.Minute = 9;
    order.Action();
    //可以取消订单
    order.IsCancel = true;
    order.Minute = 20;
    order.Action();
    order.Minute = 33;
    order.Action();
    order.Minute = 43;
    order.Action();
}

//环境角色---相当于Context类型
public sealed class Order
{
    private State current;

    public Order()
    {
        //工作状态初始化为尚无的工作状态，等待接单中
        current = new WaitForAcceptance();
        IsCancel = false;
    }
    private double minute;
    public double Minute
    {
        get { return minute; }
        set { minute = value; }
    }

    public bool IsCancel { get; set; }

    private bool finish;
    public bool TaskFinished
    {
        get { return finish; }
        set { finish = value; }
    }
    public void SetState(State s)
    {
        current = s;
    }
    public void Action()
    {
        current.Process(this);
    }
}

//抽象状态角色---相当于State类型
public interface State
{
    //处理订单
    void Process(Order order);
}

//等待受理--相当于具体状态角色
public sealed class WaitForAcceptance : State
{
    public void Process(Order order)
    {
        System.Console.WriteLine("我们开始受理，准备备货！");
        if (order.Minute < 30 && order.IsCancel)
        {
            System.Console.WriteLine("接受半个小时之内，可以取消订单！");
            order.SetState(new CancelOrder());
            order.Action();
        }
        order.SetState(new AcceptAndDeliver());
        order.TaskFinished = false;
        order.Action();
    }
}

//受理发货---相当于具体状态角色
public sealed class AcceptAndDeliver : State
{
    public void Process(Order order)
    {
        System.Console.WriteLine("我们货物已经准备好，可以发货了，不可以撤销订单！");
        if (order.Minute < 30 && order.IsCancel)
        {
            System.Console.WriteLine("接受半个小时之内，可以取消订单！");
            order.SetState(new CancelOrder());
            order.Action();
        }
        if (order.TaskFinished == false)
        {
            order.SetState(new ConfirmationReceipt());
            order.Action();
        }
    }
}

//确认收货---相当于具体状态角色
public sealed class ConfirmationReceipt : State
{
    public void Process(Order order)
    {
        System.Console.WriteLine("检查货物，没问题可以就可以签收！");
        order.SetState(new Success());
        order.TaskFinished = false;
        order.Action();
    }
}

//交易成功---相当于具体状态角色
public sealed class Success : State
{
    public void Process(Order order)
    {
        System.Console.WriteLine("订单结算");
        order.TaskFinished = true;
    }
}

//取消订单---相当于具体状态角色
public sealed class CancelOrder : State
{
    public void Process(Order order)
    {
        System.Console.WriteLine("检查货物，有问题，取消订单！");
        order.TaskFinished = true;
    }
}