抽象工廠添加到字典從配置

Question

您好我的工廠代碼是這樣的。而不是直接存儲在字典中，我想將這些值存儲在app.config文件中。如下所示。

public class HandlerFactory 
    { 
     private Dictionary<string, IHandler> _handlers = new Dictionary<string,IHandler>(); 
     public HandlerFactory() 
     { 
      _handlers.Add("AMOUNT", new AmountValidator()); 
      _handlers.Add("FLOW", new FlowValidator()); 
     } 
     public IHandler Create(string key) 
     { 
      IHandler result; 
      _handlers.TryGetValue(key, out result); 
      return result; 
     } 
    } 

我想將這些設置移動到我的配置文件中，如下所示。

<?xml version="1.0" encoding="utf-8" ?> 
     <configuration> 
     <configSections> 
      <section name="Indentifiers" type="System.Configuration.AppSettingsSection"/> 
     </configSections> 
     <Indentifiers> 
      <add key="AMOUNT" value="AmountValidator" /> 
      <add key="FLOW" value="FlowValidator" /> 
     </Indentifiers> 
    </configuration> 

我正在做這樣的事情，但我沒有成功。不知道如何添加到字典

NameValueCollection settings = ConfigurationManager.GetSection("Indentifiers") as NameValueCollection; 
       if (settings != null) 
       { 
        foreach (string key in settings.AllKeys) 
        { 
         _handlers.Add(key.ToString(), settings[key].ToString()); <-- how to handle here 
        } 
       } 

Answer 1

正如ChaosPandion指出的，CreateInstance方法應該是有用的。 假設這兩種處理程序類型的實現IHandler，它們是位於運行的程序集，

_handler.Add(key.ToString(), Activator.CreateInstance(null, settings[key].ToString())); 

應該做的伎倆！ http://msdn.microsoft.com/en-us/library/d133hta4.aspx 第一個參數是程序集的名稱，null默認爲正在執行的程序集。

Answer 2

public interface IHandler 
{ 
    void Handle(); 
} 

public sealed class HandlerFactory 
{ 
    private readonly Dictionary<string, Type> _map = new Dictionary<string, Type>(); 

    public HandlerFactory() 
    { 
     var handlers = (NameValueCollection)ConfigurationManager.GetSection("Handlers"); 
     if (handlers == null) 
      throw new ConfigurationException("Handlers section was not found."); 
     foreach (var key in handlers.AllKeys) 
     { 
      var typeName = handlers[key] ?? string.Empty; 
      // the type name must be qualified enough to be 
      // found in the current context. 
      var type = Type.GetType(typeName, false, true); 
      if (type == null) 
       throw new ConfigurationException("The type '" + typeName + "' could not be found."); 
      if (!typeof(IHandler).IsAssignableFrom(type)) 
       throw new ConfigurationException("The type '" + typeName + "' does not implement IHandler."); 
      _map.Add(key.Trim().ToLower(), type); 
     } 
    } 

    // Allowing your factory to construct the value 
    // means you don't have to write construction code in a million places. 
    // Your current implementation is a glorified dictionary 
    public IHandler Create(string key) 
    { 
     key = (key ?? string.Empty).Trim().ToLower(); 
     if (key.Length == 0) 
      throw new ArgumentException("Cannot be null or empty or white space.", "key"); 
     Type type; 
     if (!_map.TryGetValue(key, out type)) 
      throw new ArgumentException("No IHandler type maps to '" + key + "'.", "key"); 
     return (IHandler)Activator.CreateInstance(type); 
    } 
}