我目前正在使用 Unity IoC 容器,这是我的 AppConfig 类。正如你所看到的,Initialize 方法应该只被调用一次,我已经使用了双重锁检查来确保这一点。
如果我的方法不是最好的方法,那么实现这一目标的最佳方法是什么?
public interface IAppConfig
{
/// <summary>
/// Gets the admin username.
/// </summary>
/// <value>The admin username.</value>
string AdminUsername { get; }
/// <summary>
/// Gets the admin password.
/// </summary>
/// <value>The admin password.</value>
string AdminPassword { get; }
/// <summary>
/// Initializes this instance.
/// </summary>
void Initialize();
}
/// <summary>
/// A singleton App config which helps reading from web.config
/// its lifetime is controlled by Unity.
/// </summary>
public class AppConfig : IAppConfig
{
#region Fields
/// <summary>
/// the injectable config manager
/// </summary>
private readonly IConfigManager _configManager;
private readonly ILogger _logger;
private static readonly object LockObject = new object();
private static bool _initialized = false;
#endregion
#region Constructors
/// <summary>
/// Initializes a new instance of the <see cref="AppConfig"/> class.
/// </summary>
public AppConfig(IConfigManager configManager, ILogger logger)
{
this._configManager = configManager;
this._logger = logger;
}
#endregion
#region Properties
/// <summary>
/// Gets the admin username.
/// </summary>
/// <value>The admin username.</value>
public string AdminUsername { get; private set; }
/// <summary>
/// Gets the admin password.
/// </summary>
/// <value>The admin password.</value>
public string AdminPassword { get; private set; }
#endregion
#region Methods
public void Initialize()
{
if (_initialized)
{
throw new ApplicationException("Initialize method should be called only once");
}
lock(LockObject)
{
if (_initialized) return;
var adminUserNameSetting = _configManager.AppSettings[ConfigKeys.AdminUsername];
if (adminUserNameSetting == null)
{
throw new ApplicationException("AdminUsername key not found");
}
this.AdminUsername = adminUserNameSetting.Value;
if (String.IsNullOrWhiteSpace(this.AdminUsername))
{
_logger.LogError("AdminUsername not found");
}
// log
var adminPasswordSetting = _configManager.AppSettings[ConfigKeys.AdminPassword];
if (adminPasswordSetting == null)
{
throw new ApplicationException("AdminPassword key not found");
}
this.AdminPassword = adminPasswordSetting.Value;
if (String.IsNullOrWhiteSpace(this.AdminPassword))
{
_logger.LogError("AdminPassword not found");
}
_initialized = true;
}
}
#endregion
}
在Unity中,我使用以下代码:
// IAppConfig
container.RegisterType<IAppConfig, AppConfig>(new ContainerControlledLifetimeManager(),
new InjectionConstructor(configManager,
logger));
var appConfig = container.Resolve<IAppConfig>();
appConfig.Initialize();
我认为
Initalize()
方法更像是一个实现问题。这意味着它可能根本不应该出现在界面中。
初始化实例最好留给构造函数。
如果您确实需要延迟初始化,那么您可以使用布尔值和锁来解决。
根据您在 Initialize 方法中所做的判断,我认为您需要研究的是将该类注册为单例并持久化容器。您可以在此处查看执行此操作的示例:
好吧,您依靠 Unity 来确保您的类是单例。虽然 C# 的代码模式非常简单。请参阅此处。然后在构造函数中调用初始化代码。
无论如何,我都会声明你的初始化标志是易失性的,因为代码处于atmo状态。
我更喜欢有一个静态类实例变量来检查它是否已在 get 访问器中初始化。通过实例属性访问类,您将控制类初始化的次数。这几乎是默认的 C# 单例模式:
public static class MySingleton
{
private static Mutex instanceLock = new Mutex();
private static MySingleton instance;
public static MySingleton Instance
{
get
{
instanceLock.WaitOne();
if(instance == null)
{
instance = new MySingleton();
}
instanceLock.ReleaseMutex();
return instance;
}
}
private MySingleton()
{
Initialize();
}
private void Initialize()
{
// Initialize
}
}
public class MyOtherClass
{
private MySingleton singleton = MySingleton.Instance;
}
在类中创建一个内部/公共静态 bool 属性/var。再次初始化前进行验证。如果有人忽略了该步骤,在构造函数中,您可以验证属性/var 尚未设置,并抛出它已经创建的异常。