設計模式（C#）：提供者模式（七）── 設定檔與測試執行

Web.config 設定

<?xml version="1.0" encoding="utf-8"?>
<configuration>
  <configSections>
    <section name="MessageProvider" type="Pattern.Provider.MessageProviderConfigurationSection, Pattern.Provider" />
  </configSections>
  <MessageProvider defaultProvider="SqlMessageProvider">
    <providers>
      <add name="XmlMessageProvider" type="Pattern.Provider.XmlMessageProvider, Pattern.Provider" connectionStringName="XMLConnection" />
      <add name="SqlMessageProvider" type="Pattern.Provider.SqlMessageProvider, Pattern.Provider" connectionStringName="SqlConnection" />
    </providers>
  </MessageProvider>
  <connectionStrings>
    <add name="SqlConnection" connectionString="server=.;database=db;uid=sa;pwd=sa" />
    <add name="XmlConnection" connectionString="XMLPath" />
  </connectionStrings>
</configuration>

測試頁面 (Provider.aspx)

public partial class Provider : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Response.Write(Message.Insert(new MessageModel("插入", DateTime.Now)));
        Response.Write("<br />");
        Response.Write(Message.Get()[0].Message + " " + Message.Get()[0].PublishTime.ToString());
    }
}

執行結果

True
SQL方式，連接字符串是server=.;database=db;uid=sa;pwd=sa 2007-1-22 8:21:44
OK

說明

透過 defaultProvider 切換實作，無需修改程式碼即可在 SQL 與 XML 儲存方式間切換，展現提供者模式「組態優於程式碼」的優勢。