好吧，您只需要使用convention over configuration 方法即可。
例如，你可以定义一个带有注册的通用接口：
using System;
using System.Linq;
public class Program
{
public static void Main()
{
var handlerType = typeof(IHandleKey);
var classes = typeof(Program).Assembly // you can get them however you want
.GetTypes()
.Where(p => handlerType.IsAssignableFrom(p) && p.IsClass)
.Select(t => (IHandleKey)Activator.CreateInstance(t)) // or use IoC to resolve them...
.ToArray();
while(true) {
var key = Console.ReadLine(); // or however you get your input
var handler = classes.FirstOrDefault(x => x.Key == key);
if (handler == null) {
Console.WriteLine("Couldn't find a handler for " + key);
} else {
handler.Handle();
}
}
}
}
public interface IHandleKey
{
String Key { get; }
void Handle();
}
public class Banana : IHandleKey
{
public String Key { get { return "u"; } }
public void Handle()
{
Console.WriteLine("I did banana work");
}
}
这样，如果您需要开发一项新功能，您只需添加一个包含有效密钥和实现逻辑信息的类。
同样，如果您不想让实例准备好处理命令，您可以拆分它并在类型上设置一个描述键的属性，如下所示：
using System;
using System.Linq;
public class Program
{
public static void Main()
{
var handlerType = typeof(IHandleKey);
var classes = typeof(Program).Assembly
.GetTypes()
.Where(p => handlerType.IsAssignableFrom(p) && p.IsClass && p.GetCustomAttributes(typeof(KeyHandlerAttribute), false).Count() > 0) // note we're checking for attribute here. This can be optimised.
.ToArray();
while(true) {
var key = Console.ReadLine(); // or however you get your input
var concreteType = classes.FirstOrDefault(x => ((KeyHandlerAttribute)(x.GetCustomAttributes(typeof(KeyHandlerAttribute), false).First())).Key == key);
if (concreteType == null) {
Console.WriteLine("Couldn't find a handler for " + key);
} else {
var handler = (IHandleKey)Activator.CreateInstance(concreteType); // or use IoC to resolve them...
handler.Handle();
}
}
}
}
public interface IHandleKey
{
void Handle();
}
[AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
public class KeyHandlerAttribute: Attribute
{
public String Key { get; set; }
}
[KeyHandler(Key = "u")]
public class Banana : IHandleKey
{
public void Handle()
{
Console.WriteLine("I did banana work");
}
}
更新这是使用第二种变体并实现共享状态和基于事件的通信的更新程序列表。
老实说，我觉得这很琐碎，所以请随时提出任何问题，因为我不确定什么会显得更令人困惑，什么不会...
using System;
using System.Linq;
using System.Collections.Generic;
namespace Whatever
{
public class Program
{
public static void Main()
{
// This part belongs to IoC as a Singleton
var state = new State();
// This part belongs to IoC as scoped services
var handlerType = typeof(IHandleKey);
var dict = new Dictionary<String, Object>();
foreach (var type in typeof(Program).Assembly
.GetTypes()
.Where(p => handlerType.IsAssignableFrom(p) && p.IsClass))
{
var attributes = type.GetCustomAttributes(typeof(KeyHandlerAttribute), false);
if (attributes.Any())
{
var attribute = (KeyHandlerAttribute)attributes.First();
var handlr = (IHandleKey)Activator.CreateInstance(type);
handlr.RegisterEvent(state);
dict.Add(attribute.Key, handlr);
}
}
// Main routine here
while (true)
{
var key = Console.ReadLine(); // or however you get your input
var handler = dict.ContainsKey(key) ? (IHandleKey)dict[key] : null;
if (handler == null)
{
Console.WriteLine("Couldn't find a handler for " + key);
}
else
{
handler.Handle();
}
}
}
}
// This class allows us to share state.
public class State : ISharedState
{
// As required by the question, this is an event.
public event EventHandler StateChanged;
public void RaiseStateChange(object sender)
{
this.StateChanged.Invoke(sender, new EventArgs());
}
}
// This makes our Handlers unit testable.
public interface ISharedState
{
event EventHandler StateChanged;
void RaiseStateChange(object sender);
}
// Familiar interface -> note how we have a 'register event' method now.
// We could instead just use a constructor on the HandlerBase. This is really dealer's choice now.
public interface IHandleKey
{
void Handle();
void RegisterEvent(ISharedState state);
}
[AttributeUsage(AttributeTargets.Class, AllowMultiple = false)]
public class KeyHandlerAttribute : Attribute
{
public String Key { get; set; }
}
// To avoid boilerplate in our handlers for registering/unregistering events we have a base handler class now.
public abstract class HandlerBase: IHandleKey
{
protected ISharedState _state;
public abstract void Handle();
public void RegisterEvent(ISharedState state)
{
this._state = state;
this._state.StateChanged += OnStateChanged;
}
public abstract void OnStateChanged(object sender, EventArgs e);
~HandlerBase()
{
this._state.StateChanged -= OnStateChanged;
}
}
// Actual handlers...
[KeyHandler(Key = "u")]
public class Banana : HandlerBase
{
public override void Handle()
{
Console.WriteLine("I did banana work");
this._state.RaiseStateChange(this);
}
public override void OnStateChanged(object sender, EventArgs e)
{
if (sender != this) // optional, in case we don't want to do this for self-raised changes
{
Console.WriteLine("State changed inside Banana handler");
}
}
}
[KeyHandler(Key = "c")]
public class Cheese : HandlerBase
{
public override void Handle()
{
Console.WriteLine("I did cheese work");
this._state.RaiseStateChange(this);
}
public override void OnStateChanged(object sender, EventArgs e)
{
if (sender != this) // optional, in case we don't want to do this for self-raised changes
{
Console.WriteLine("State changed inside cheese handler");
}
}
}
}