c# – 如果要在从接口继承的不同类之间进行选择,如何不违反OCP？

我有一个接口让我说ISendOut,我从它继承了两个不同的类
例如TransferViaSerialPort和TransferViaWirelessModule(我的意思是在这两个类中实现这个接口).如何设计我的软件,使用户能够选择(在UI中)通过SerialPort或WirelessModule发送他/她的数据的方法,而不是违反OCP？因为如果我想要一个“Switch Case”或“If / Else”语句,我会违反OCP.

解决方法:

您需要使用工厂模式.要使Factory Pattern动态化,您可以使用Reflection并在UI中显示类的类型,这些类是从ISendOut实现的,您可以使用自定义属性或其他方法(如使用Dictionary).

[System.AttributeUsage(System.AttributeTargets.Class)]
public class DisplayNameAttribute : Attribute
{
    public DisplayNameAttribute(string displayName)
    {
        DisplayName = displayName;
    }

    public string DisplayName { get; set; }
}

public interface ISendOut
{
    void Send(string data);
}

[DisplayName("Wireless")]
public class WirelessSendOut : ISendOut
{
    public void Send(string data)
    {
        MessageBox.Show("data sent through wireless.");
    }
}

[DisplayName("Serial")]
public class SerialSendOut : ISendOut
{
    public void Send(string data)
    {
        MessageBox.Show("data sent through serial port.");
    }
}

public static class SendOutFactory
{
    public static ISendOut CreateSendOut(string typeName)
    {
        var types = Assembly.GetExecutingAssembly().GetTypes();
        var sendOutType = types.First(x => (typeof(ISendOut)).IsAssignableFrom(x) && x.Name == typeName);
        return (ISendOut) Activator.CreateInstance(sendOutType);
    }
}

public static class SendOutDiscovery
{
    public static IEnumerable<NameType> Discover()
    {
        var types = Assembly.GetExecutingAssembly().GetTypes();
        var sendOutTypes = types.Where(x => x != typeof(ISendOut) && (typeof(ISendOut)).IsAssignableFrom(x));
        return sendOutTypes.Select(type => GetNameType(type)).ToList();
    }

    private static NameType GetNameType(Type type)
    {
        var nameType = new NameType
                           {
                               DisplayName = GetDisplayName(type),
                               TypeName = type.Name
                           };
        return nameType;
    }

    private static string GetDisplayName(Type type)
    {
        return ((DisplayNameAttribute)type.GetCustomAttributes(typeof (DisplayNameAttribute), false).First()).DisplayName;
    }
}

public class NameType //for binding in UI
{
    public string DisplayName { get; set; }
    public string TypeName { get; set; }
}

public class SendOutViewModel //sample using in wpf (window contains a combobox)
{
    public SendOutViewModel()
    {
        SendTypes = new ObservableCollection<NameType>(SendOutDiscovery.Discover());
    }

    public NameType SelectedSendType { get; set; } //bind to selected item in combobox

    public ObservableCollection<NameType> SendTypes { get; private set; } //bind to item source of combo

    public string Data { get; set; } //data to be sent

    public void Send()
    {
        ISendOut sendOut = SendOutFactory.CreateSendOut(SelectedSendType.TypeName);
        sendOut.Send(Data);
    }
}

后来我在不修改现有代码的情况下添加了UsbSendOut(所以没有破坏OCP)

[DisplayName("Usb")]
public class UsbSendOut : ISendOut
{
    public void Send(string data)
    {
        MessageBox.Show("data sent through usb.");
    }
}

标签：c,oop,design-patterns,design-principles
来源： https://codeday.me/bug/20190626/1291653.html