如何实现Singleton，它在C＃中从db填充其值？

I am trying to implement the Jon Skeet's example

我正在尝试实施Jon Skeet的例子

public sealed class Singleton
{
    Singleton()
    {
    }

    public static Singleton Instance
    {
        get
        {
            return Nested.instance;
        }
    }

    class Nested
    {
        // Explicit static constructor to tell C# compiler
        // not to mark type as beforefieldinit
        static Nested()
        {
        }

        internal static readonly Singleton instance = new Singleton();
    }
}

2 个解决方案

#1

Do all your database operations in the constructor for Singleton.

在Singleton的构造函数中执行所有数据库操作。

Without knowing what those operations are, we can't really provide much more help - but that's where you should put them. Obviously that doesn't mean creating a massive constructor - you can still split the code up into normal methods, but you need to call them from the constructor.

在不知道这些操作是什么的情况下,我们无法真正提供更多帮助 - 但这就是你应该放置它们的地方。显然,这并不意味着创建一个庞大的构造函数 - 您仍然可以将代码拆分为普通方法,但是您需要从构造函数中调用它们。

#2

Almost straight copy paste from the BlogEngine ...

来自BlogEngine的几乎直接的复制粘贴......

    System.Collections.Specialized.ListDictionary lstSettings;
    string msg; 

    MyApp.Bo.AppUser objAppUser = new AppUser();
    MyApp.Db.SqlServer2008Provider p = new MyApp.Db.SqlServer2008Provider(objAppUser);



    p.LoadSettings(out msg, out lstSettings); 

    foreach (string key in lstSettings.Keys)
    {

        string name = key;
        string value = (string)lstSettings[key];

        #region CycleTroughobjAppSettingProperties
        Type objAppSettingsType = typeof(MyApp.Bo.AppSettings);
        foreach (PropertyInfo propInfo in objAppSettingsType.GetProperties())
        {
            if (propInfo.Name.Equals(name, StringComparison.OrdinalIgnoreCase))
            {

                try
                {
                    propInfo.SetValue(this, Convert.ChangeType(value, propInfo.PropertyType, CultureInfo.CurrentCulture), null);
                }
                catch
                {
                    logger.Fatal("Failed setting the Application settings ");
                }
                break;
            }
        }
        #endregion CycleTroughobjAppSettingProperties
    }

#1