学习cnblogsGuestBook V2.0

下载了cnblogsGuestBook V2.0 的源码，在Vs.net里调试了一下，并照着它的思路自己重做了一个。
对“窗体设计器”有了一个新的认识，可见偶的菜鸟看点http://www.cnblogs.com/lovewangshu/archive/2005/03/22/123305.html
通过“窗体设计器”往页面上拖Connection、DataAdapter、DataSet对象，在页面类中自动添加对应的类属性，如：

public class _default : System.Web.UI.Page
    {
        protected System.Web.UI.WebControls.TextBox txtboxTitle;
        protected System.Web.UI.WebControls.TextBox txtboxContent;
        protected System.Web.UI.HtmlControls.HtmlTableCell TD1;
        protected System.Data.OleDb.OleDbDataAdapter da;
        protected System.Data.OleDb.OleDbConnection conn;
        protected System.Web.UI.WebControls.DataList dlList;
        protected System.Data.OleDb.OleDbCommand oleDbSelectCommand1;
        protected System.Data.OleDb.OleDbCommand oleDbInsertCommand1;
        protected System.Data.OleDb.OleDbCommand oleDbUpdateCommand1;
        protected System.Data.OleDb.OleDbCommand oleDbDeleteCommand1;
        protected cnblogsGuestbook.ds ds1;
        protected System.Web.UI.WebControls.Button btnSubmit;

根据自己的配置，“窗体设计器”自动生成初始化的方法，如：

    private void InitializeComponent()
        {    
            this.da = new System.Data.OleDb.OleDbDataAdapter();
            this.oleDbDeleteCommand1 = new System.Data.OleDb.OleDbCommand();
            this.conn = new System.Data.OleDb.OleDbConnection();
            this.oleDbInsertCommand1 = new System.Data.OleDb.OleDbCommand();
            this.oleDbSelectCommand1 = new System.Data.OleDb.OleDbCommand();
            this.oleDbUpdateCommand1 = new System.Data.OleDb.OleDbCommand();
            this.ds1 = new cnblogsGuestbook.ds();
            ((System.ComponentModel.ISupportInitialize)(this.ds1)).BeginInit();
            this.dlList.ItemCommand += new System.Web.UI.WebControls.DataListCommandEventHandler(this.dlList_ItemCommand);
            this.btnSubmit.Click += new System.EventHandler(this.btnSubmit_Click);
            // 
            // da
            // 
            this.da.DeleteCommand = this.oleDbDeleteCommand1;
            this.da.InsertCommand = this.oleDbInsertCommand1;
            this.da.SelectCommand = this.oleDbSelectCommand1;
            this.da.TableMappings.AddRange(new System.Data.Common.DataTableMapping[] {
                                                                                         new System.Data.Common.DataTableMapping("Table", "tbl_msg", new System.Data.Common.DataColumnMapping[] {
                                                                                            new System.Data.Common.DataColumnMapping("msg_content", "msg_content"),
                                                                                                                                                                                                    new System.Data.Common.DataColumnMapping("msg_id", "msg_id"),
                                                                                                                                                                                                    new System.Data.Common.DataColumnMapping("msg_time", "msg_time"),
                                                                                                                                                                                                    new System.Data.Common.DataColumnMapping("msg_title", "msg_title")})});
            this.da.UpdateCommand = this.oleDbUpdateCommand1;
..
}

 

  这个方法在override protected void OnInit(EventArgs e)中被调用，

override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。
            //
            InitializeComponent();
            base.OnInit(e);
        }

页面第一次被打开时，执行顺序为：OnInit()-------InitializeComponent()-------base.OnInit(e)------Page_Load()
可以理解为页面类的构造过程中已经完成了页面类属性的初始化，页面类的其他方法，可以直接使用这些属性。这样，可以避免V1.0 中出现的其他方法重复配置Ado.net组件的毛病。

偶对V2.0 的认识在于：V2.0 充分利用了“页面”相当于“类”，以及“类”的一些操作特点，来实现留言本。