如何在這種情況下使用Microsoft Unity？

Question

假設我有一個IBookRepository接口並由SybaseAsaBookRepository和XMLBookRepository實現。

SybaseAsaBookRepository構造函數要求2參數，數據庫用戶標識和密碼，這兩個值都可以由IBookAppConfiguration實例檢索。 XMLBookRepository構造函數不需要參數。

顯然IBookAppConfiguration可以很容易地配置爲Microsoft Unity來分解，我們甚至假設它是一個Singleton。

現在，我該如何配置Microsoft Unity，將IBookRepository接口解析爲SybaseAsaBookRepository，並正確提供了所需的2個構造函數參數？

示例代碼如下所示：

public interface IBookRepository 
{ 
    /// <summary> 
    /// Open data source from Sybase ASA .db file, or an .XML file 
    /// </summary> 
    /// <param name="fileName">Full path of Sybase ASA .db file or .xml file</param> 
    void OpenDataSource(string fileName); 

    string[] GetAllBookNames(); // just return all book names in an array 
} 

public interface IBookAppConfiguration 
{ 
    string GetUserID(); // assuming these values can only be determined 
    string GetPassword(); // during runtime 
} 

public class SybaseAsaBookRepository : IBookRepository 
{ 
    public DatabaseAccess(string userID, string userPassword) 
    { 
     //... 
    } 
} 

<register type="IBookAppConfiguration" mapTo="BookAppConfigurationImplementation"> 
    <lifetime type="singleton"/> 
</register> 

<register name="SybaseAsa" type="IBookRepository" mapTo="SybaseAsaBookRepository"> 
    <constructor> 
     <param name="userID" value="??? what shall i put it here???"/> 
     <param name="userPassword" value="??? what shall i put it here???"/> 
    </constructor> 
</register> 

Answer 1

您可以更改SybaseAsaBookRepository的參數列表接受IBookAppConfiguration的一個實例：

public class SybaseAsaBookRepository : IBookRepository 
{ 
    public SybaseAsaBookRepository(IBookAppConfiguration configuration) 
    { 
     string userID = configuration.GetUserID(); 
     string userPassword = configuration.GetPassword(); 
     ... 
    } 
} 

您的註冊信息必須是：

<register name="SybaseAsa" type="IBookRepository" mapTo="SybaseAsaBookRepository" /> 

這可以使用，因爲Unity知道