C#中DropDownList动态生成的方法
程序员文章站
2023-12-03 11:21:58
本文实例讲述了c#中dropdownlist动态生成的方法。分享给大家供大家参考。具体分析如下：
今天学习了dropdownlist的动态生成 以及asp.net的生命周...
本文实例讲述了c#中dropdownlist动态生成的方法。分享给大家供大家参考。具体分析如下：
今天学习了dropdownlist的动态生成 以及asp.net的生命周期，还有viewstate，因为项目需要根据需求动态生成条件 所以研究了一部分代码来完成这些工作，好了话不多说了，来看代码
首先是网页的代码：
<span style="font-size:18px;"><body>
<form id="form1" runat="server">
<div>
<asp:placeholder id="placeholder1" runat="server"></asp:placeholder>
//placeholder控件相当于一个容器，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";
//数据库读取
string[] arr = str.split('/');
if (arr.length == placeholder1.controls.count)
//防止新增类别时读取出错
{
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();
//具体添加的操作
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);
}
}
希望本文所述对大家的c#程序设计有所帮助。