如何在这种情况下使用微软Unity

Question

假设我有一个IBookRepository接口，由SybaseAsaBookRepository和XMLBookRepository实现。

SybaseAsaBookRepository构造函数需要2个参数，数据库用户id和密码，这两个值都可以被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来解析，让我们甚至假设它是一个单例。

现在，我如何配置微软统一，以解决IBookRepository接口到SybaseAsaBookRepository，与所需的2构造函数参数正确服务?

示例代码如下:

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

你可以改变SybaseAsaBookRepository的参数列表来接受IBookAppConfiguration的一个实例:

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

您的注册必须是:

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

这个可以使用，因为Unity知道