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C#中DropDownList動(dòng)態(tài)生成的方法

更新時(shí)間：2015年03月27日 14:47:20 作者：小啊斌

這篇文章主要介紹了C#中DropDownList動(dòng)態(tài)生成的方法,實(shí)例分析了C#中DropDownList的使用技巧,非常具有實(shí)用價(jià)值,需要的朋友可以參考下

本文實(shí)例講述了C#中DropDownList動(dòng)態(tài)生成的方法。分享給大家供大家參考。具體分析如下：

今天學(xué)習(xí)了DropDownList的動(dòng)態(tài)生成以及asp.net的生命周期，還有ViewState，因?yàn)轫?xiàng)目需要根據(jù)需求動(dòng)態(tài)生成條件所以研究了一部分代碼來(lái)完成這些工作，好了話不多說(shuō)了，來(lái)看代碼

首先是網(wǎng)頁(yè)的代碼：

<span style="font-size:18px;"><body>
  <form id="form1" runat="server">
  <div>
    <asp:PlaceHolder ID="PlaceHolder1" runat="server"></asp:PlaceHolder>
 //placeholder控件相當(dāng)于一個(gè)容器，用于存放其他控件
    <br />
    <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="Button"/></div>
  </form>
</body></span>

下面是c#程序

public partial class _Default : System.Web.UI.Page
{
  private CategoryBLL _categoryBLL = new CategoryBLL();
  private Category _category = new Category();
  private void Page_Init(object sender, System.EventArgs e)
  //可以看一下asp的生命周期
  {
    BindDrpClass();
  }
  protected void Page_Load(object sender, EventArgs e)
  {
    string str = "8/14/19/25";
 //數(shù)據(jù)庫(kù)讀取
    string[] arr = str.Split('/');
    if (arr.Length == PlaceHolder1.Controls.Count)
 //防止新增類別時(shí)讀取出錯(cuò)
    {
      for (int i = 0; i < PlaceHolder1.Controls.Count; i++)
      {
        if (PlaceHolder1.Controls[i] is DropDownList)
        {
          ((DropDownList)PlaceHolder1.Controls[i]).SelectedValue = arr[i];
        }
      }
    }
  }
  private void BindDrpClass()
  {
    DataTable dt = _categoryBLL.GetCategory();
    DataRow[] drs = dt.Select("pid=0");
    foreach (DataRow dr in drs)
    {
      string id = dr["id"].ToString();
      string name = dr["name"].ToString();
      DropDownList ddl = new DropDownList();
      //具體添加的操作
      ddl.Items.Clear();
      ddl.ID = "ddl" + id;
      ddl.Items.Add(new ListItem("－" + name + "－", id));
      PlaceHolder1.Controls.Add(ddl);
      int sonparentid = int.Parse(id);
      BindDrpNode(sonparentid, dt, ddl);
    }
  }
  private void BindDrpNode(int parentid, DataTable dt, DropDownList ddl)
  {
    DataRow[] drs = dt.Select("pid= " + parentid);
    foreach (DataRow dr in drs)
    {
      string id = dr["id"].ToString();
      string name = dr["name"].ToString();
      ddl.Items.Add(new ListItem(name, id));
      PlaceHolder1.Controls.Add(ddl);
    }
  }
  protected void Button1_Click(object sender, EventArgs e)
  {
    string category = "";
    string category2 = "";
    foreach (Control childControl in PlaceHolder1.Controls)
    {
      if (childControl is DropDownList) 
      {
        category += "/" + ((DropDownList)childControl).SelectedItem.Text;
        category2 += "/" + ((DropDownList)childControl).SelectedValue;
      }
    }
    if (category.Length > 0)
      category = category.Remove(0, 1);
    Response.Write(category);
    Response.Write("<br />"); 
    if (category2.Length > 0)
      category2 = category2.Remove(0, 1);
    Response.Write(category2);
  }
}

希望本文所述對(duì)大家的C#程序設(shè)計(jì)有所幫助。

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