provider模式学习——simpledemo

1.首先建立一个类库项目：Provider Demo，添加如下类：并要添加引用System.Configuration

1.1 创建ParentProvider类继承自provider的基类：

namespace provider.Provider{    public abstract class ParentProvider : ProviderBase    {        public abstract string ShowData();    }}

1.2 创建ParentProviderCollection类继承自ProviderCollection基类

namespace provider.Provider{    /// <summary>    /// 该类用于管理provider的集合    /// </summary>    public class ParentProviderCollection : ProviderCollection    {        /// <summary>        /// 获取指定名称的provider，从几何中获得名称为name的provider        /// </summary>        /// <param name="name"></param>        /// <returns></returns>        public new ParentProvider this[string name]        {            get { return (ParentProvider)base[name]; }        }        /// <summary>        /// 重写基类中添加provider到集合的方法        /// </summary>        /// <param name="provider"></param>        public override void Add(ProviderBase provider)        {            if (provider == null)                throw new ArgumentNullException("Provider");            if (!(provider is ParentProvider))                throw new ArgumentException("Invalid provider type", "provider");            base.Add(provider);        }    }}

1.3创建ParentProviderConfigurationSection类继承自ConfigurationSection

namespace provider.Provider{    /// <summary>    /// 这个类可以看成是一个管理配置文件中节点的类，    /// 这个类中属性使用Attribute的方式声明值，具体里面的值可以通过反射得到    /// </summary>    public class ParentProviderConfigurationSection : ConfigurationSection    {        /// <summary>        /// 获取配置文件中配置节名称为Providers的信息        /// </summary>        [ConfigurationProperty("providers")]        public ProviderSettingsCollection Providers        {            get { return (ProviderSettingsCollection)base["providers"]; }        }        //[StringValidator(MinLength=1)]        [ConfigurationProperty("defaultProvider")]        public string DefaultProvider        {            get { return (string)base["defaultProvider"];}            set { base["defaultProvider"]=value;}        }    }}

1.4创建ChineseProvider继承自ParentProvider

namespace provider.Provider{    public class ChineseProvider:ParentProvider    {        public override string ShowData()        {            return "你好，欢迎来到中国";        }    }}

1.5创建EnglishProvider继承自ParentProvider

namespace provider.Provider{   public  class EnglishProvider:ParentProvider    {       public override string ShowData()       {           return "hello ,welcome to china";       }    }}

2.编译该类库项目生成程序集文件

3.新建c#窗体项目

3.1 添加providerDemo.dll的引用

3.2 添加引用System.Configuration

3.3  修改配置文件

<configuration><configSections><section name ="parentProvider" type ="provider.Provider.ParentProviderConfigurationSection,providerDemo"/></configSections><parentProvider defaultProvider="ChineseProvider"><providers><add name="ChineseProvider" type="provider.Provider.ChineseProvider"/><add name="EnglishProvider" type="provider.Provider.EnglishProvider"/></providers></parentProvider></configuration>

3.4 主窗体事件响应代码

public partial class Form1 : Form    {        private ParentProvider provider;        private ParentProviderCollection providerCollection;        public Form1()        {            InitializeComponent();        }        private void btnC_Click(object sender, EventArgs e)        {            LoadProvider("ChineseProvider");            txtDisplay.Text = provider.ShowData();        }        private void btnE_Click(object sender, EventArgs e)        {            LoadProvider("EnglishProvider");            txtDisplay.Text = provider.ShowData();        }        private void Form1_Load(object sender, EventArgs e)        {            LoadProvider(null);            txtDisplay.Text = provider.ShowData();        }        private void LoadProvider(string providerSelected)        {            ParentProviderConfigurationSection config = null;            config = (ParentProviderConfigurationSection)ConfigurationManager.GetSection("parentProvider");            providerCollection = new ParentProviderCollection();            ProviderHelper.InstantiateProviders(config.Providers, providerCollection, typeof(ParentProvider));            provider = providerCollection[providerSelected ?? config.DefaultProvider];        }    }

4.运行结果展示

4.1 窗体加载：（使用默认的provider）

4.2 English按钮点击

4.3 Chinese按钮点击