如何在这种情况下使用Microsoft Unity？

Question

假设我有一个IBookRepository接口并由SybaseAsaBookRepository和XMLBookRepository实现。

SybaseAsaBookRepository构造函数要求2参数，数据库用户标识和密码，这两个值都可以由IBookAppConfiguration实例检索。 XMLBookRepository构造函数不需要参数。

显然IBookAppConfiguration可以很容易地配置为Microsoft Unity来分解，我们甚至假设它是一个Singleton。

现在，我该如何配置Microsoft Unity，将IBookRepository接口解析为SybaseAsaBookRepository，并正确提供了所需的2个构造函数参数？

示例代码如下所示：

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的参数列表接受IBookAppConfiguration的一个实例：

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

您的注册信息必须是：

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

这可以使用，因为Unity知道