封装读取配置文件类

AppSettings.cs

public static class AppSettings
    {

        public static T GetSettingByKey<T>(string key, T defaultValue = default(T))
        {
            key = key.Trim().ToLowerInvariant();
            var settings = GetAllSettings();
            if (settings.ContainsKey(key))
                return CommonHelper.To<T>(settings[key].Value);

            return defaultValue;
        }

        public static TSettings GetSetting<TSettings>()
        {
            var Settings = Activator.CreateInstance<TSettings>();

            // get properties we can write to
            var properties = from prop in typeof(TSettings).GetProperties()
                             where prop.CanWrite && prop.CanRead
                             let setting = AppSettings.GetSettingByKey<string>(typeof(TSettings).Name + "." + prop.Name)
                             where setting != null
                             where CommonHelper.GetNopCustomTypeConverter(prop.PropertyType).CanConvertFrom(typeof(string))
                             where CommonHelper.GetNopCustomTypeConverter(prop.PropertyType).IsValid(setting)
                             let value = CommonHelper.GetNopCustomTypeConverter(prop.PropertyType).ConvertFromInvariantString(setting)
                             select new { prop, value };

            // assign properties
            properties.ToList().ForEach(p => p.prop.SetValue(Settings, p.value, null));
            return Settings;
        }

        public static IDictionary<string, KeyValuePair<int, string>> GetAllSettings()
        {
            var settings = new Dictionary<string, KeyValuePair<int, string>>();
            var appSettings = ConfigurationManager.AppSettings;
            foreach (var setting in appSettings.AllKeys)
            {
                settings.Add(setting.ToLowerInvariant(), new KeyValuePair<int, string>(0, appSettings[setting]));
            }

            return settings;
        }
    }

CommonHelper.cs

/// <summary>
    /// Represents a common helper
    /// </summary>
    public partial class CommonHelper
    {
        
        /// <summary>
        /// Converts a value to a destination type.
        /// </summary>
        /// <param name="value">The value to convert.</param>
        /// <param name="destinationType">The type to convert the value to.</param>
        /// <returns>The converted value.</returns>
        public static object To(object value, Type destinationType)
        {
            return To(value, destinationType, CultureInfo.InvariantCulture);
        }

        /// <summary>
        /// Converts a value to a destination type.
        /// </summary>
        /// <param name="value">The value to convert.</param>
        /// <param name="destinationType">The type to convert the value to.</param>
        /// <param name="culture">Culture</param>
        /// <returns>The converted value.</returns>
        public static object To(object value, Type destinationType, CultureInfo culture)
        {
            if (value != null)
            {
                var sourceType = value.GetType();

                TypeConverter destinationConverter = GetNopCustomTypeConverter(destinationType);
                TypeConverter sourceConverter = GetNopCustomTypeConverter(sourceType);
                if (destinationConverter != null && destinationConverter.CanConvertFrom(value.GetType()))
                    return destinationConverter.ConvertFrom(null, culture, value);
                if (sourceConverter != null && sourceConverter.CanConvertTo(destinationType))
                    return sourceConverter.ConvertTo(null, culture, value, destinationType);
                if (destinationType.IsEnum && value is int)
                    return Enum.ToObject(destinationType, (int)value);
                if (!destinationType.IsAssignableFrom(value.GetType()))
                    return Convert.ChangeType(value, destinationType, culture);
            }
            return value;
        }

        /// <summary>
        /// Converts a value to a destination type.
        /// </summary>
        /// <param name="value">The value to convert.</param>
        /// <typeparam name="T">The type to convert the value to.</typeparam>
        /// <returns>The converted value.</returns>
        public static T To<T>(object value)
        {
            //return (T)Convert.ChangeType(value, typeof(T), CultureInfo.InvariantCulture);
            return (T)To(value, typeof(T));
        }

        public static TypeConverter GetNopCustomTypeConverter(Type type)
        {
            /*if (type == typeof(List<int>))
                return new GenericListTypeConverter<int>();*/
            return TypeDescriptor.GetConverter(type);
        }

    }

App.config

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings>
    <add key="Setting1" value="SomeValue"/>
    <add key="Setting2" value="25"/>
    <add key="Setting3" value="12/25/2010"/>

    <add key="TestSettings.ServerName" value="Ruby"/>
    <add key="TestSettings.Ip" value="192.168.0.1"/>
    <add key="TestSettings.PortNumber" value="21"/>
    <add key="TestSettings.Username" value="admin"/>
    <add key="TestSettings.Password" value="password"/>
  </appSettings>
</configuration>

UnitTest1.cs

[TestMethod]
        public void Can_get_all_settings()
        {
            var settings = AppSettings.GetAllSettings();
            Assert.IsNotNull(settings);
            Assert.IsTrue(settings.Count > 0);
        }

        [TestMethod]
        public void Can_get_setting_by_key()
        {
            var setting = AppSettings.GetSettingByKey<string>("Setting1");
            Assert.AreEqual(setting, "SomeValue");
        }

        [TestMethod]
        public void Can_get_typed_setting_value_by_key()
        {
            var setting = AppSettings.GetSettingByKey<DateTime>("Setting3");
            Assert.AreEqual(setting, new DateTime(2010, 12, 25));
        }

        [TestMethod]
        public void Default_value_returned_if_setting_does_not_exist()
        {
            var setting = AppSettings.GetSettingByKey<int>("NonExistentKey", 100);
            Assert.AreEqual(setting, 100);
        }

        [TestMethod]
        public void Can_get_settings()
        {
            // requires settings to be set in app.config in format TestSettings.[PropertyName]
            var settings = AppSettings.GetSetting<TestSettings>();
            settings.ServerName.ShouldEqual("Ruby");
            settings.Ip.ShouldEqual("192.168.0.1");
            settings.PortNumber.ShouldEqual(21);
            settings.Username.ShouldEqual("admin");
            settings.Password.ShouldEqual("password");
        }

学习nop中读取配置文件的方式。读取方法改成了静态方法。提取出来单独使用。