“asp.net联动列表框”的意思、由来-中文百科全书

词条

asp.net联动列表框

释义

§ 介绍

另类无刷新、联动下拉列表框（二级+XMLHttpRequest)

二级的联动下拉列表，从思路上讲，大致分下列几步：

一：触发第一个下拉列表的onchange事件。

二：异步调用处理页后，会返回处理请求后的信息（服务器端用Response.Write方法写入要返回的字符串，客户端用responseText属性接收字符串。

三：用得到的字符串处理后更新第二个下拉列表框

§ 主要代码如下：

一：建立读取XML的类，这里也可以是数据库的查询

public class ReadXmlCS

{

public const string k = "|";

public const string s = ",";

public ReadXmlCS()

{

// TODO: 在此处添加构造函数逻辑

}

public static string QueryXml(string filename,string querystr)// @"//Pro_class/@id"

{

System.Text.StringBuilder sb = new System.Text.StringBuilder();

System.Xml.XPath.XPathDocument myXPathDocument = new System.Xml.XPath.XPathDocument(filename);

System.Xml.XPath.XPathNavigator myXPathNavigator = myXPathDocument.CreateNavigator();

try

{

System.Xml.XPath.XPathNodeIterator myXPathNodeIterator = myXPathNavigator.Select(querystr);

while(myXPathNodeIterator.MoveNext())

{

sb.Append(myXPathNodeIterator.Current.Value.ToString() +",");//把属性值添加到字符串末尾，添加分组字符“，”

System.Xml.XPath.XPathNavigator myXPathNavigator2 = myXPathNodeIterator.Current.Clone();//克隆当前接点

// 　 while(myXPathNavigator2.MoveToNextAttribute())//移动指针到下一个属性

// 　 {

// 　 sb.Append(myXPathNavigator2.Value.ToString()+"|");//把属性值添加到字符串末尾，添加分组字符“|”

// 　 }

myXPathNavigator2.MoveToNextAttribute();

sb.Append(myXPathNavigator2.Value.ToString()+"|");

}

return sb.ToString();

}

catch{return null;}

}

public static void QueryXml(string filename,string querystr,System.Web.UI.WebControls.DropDownList dd)// @"//Pro_class/@id"

{

System.Xml.XPath.XPathDocument myXPathDocument = new System.Xml.XPath.XPathDocument(filename);

System.Xml.XPath.XPathNavigator myXPathNavigator = myXPathDocument.CreateNavigator();

try

{

System.Xml.XPath.XPathNodeIterator myXPathNodeIterator = myXPathNavigator.Select(querystr);

while(myXPathNodeIterator.MoveNext())

{

System.Web.UI.WebControls.ListItem li = new System.Web.UI.WebControls.ListItem();

li.Value = myXPathNodeIterator.Current.Value.ToString() ;//把属性值(id)添加到ListItem的“值”属性

System.Xml.XPath.XPathNavigator myXPathNavigator2 = myXPathNodeIterator.Current.Clone();//克隆当前接点

// 　 while(myXPathNavigator2.MoveToNextAttribute())//移动指针到下一个属性

// 　 {

// 　 li.Text = myXPathNavigator2.Value.ToString();//把属性值(title)添加到ListItem的“文本”属性

// 　 }

myXPathNavigator2.MoveToNextAttribute();

li.Text = myXPathNavigator2.Value.ToString();

dd.Items.Add(li);

}

catch{}

}

其中关键的步骤加了注释，其它的大家可以到MSDN上去查找。

二。实现（WebForm8.aspx.cs页面）：

protected System.Web.UI.WebControls.DropDownList DropDownList2;

protected System.Web.UI.WebControls.DropDownList Dropdownlist1;

private void Page_Load(object sender, System.EventArgs e)

{

// 在此处放置用户代码以初始化页面

string str = this.Request.QueryString【"querychild"】;

if((str != null) && (str == "yes"))

{

string querystr = "//Pro_class【" + this.Request【"parentid"】 + "】/Pro_class_small/@id";

string show = zlp.str.ReadXmlCS.QueryXml(@"D:\\Inetpub\\wwwroot\\zlp\\XmlData\\ProductMenu.xml",querystr);

this.Response.Write(show);

this.Response.End();

}

if(!this.IsPostBack)

{

this.BindDropDownList();//加载页面时，填充第一个下拉列表框

}

protected void BindDropDownList()

{

this.Dropdownlist1.Attributes.Add("onchange","javascript:XmlPost(this);"); //服务器端添加属性

zlp.str.ReadXmlCS.QueryXml(@"D:\\Inetpub\\wwwroot\\zlp\\XmlData\\ProductMenu.xml",@"//Pro_class/@id",this.Dropdownlist1);

}

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