Ajax简单示例之改变下拉框动态生成表格-优快云博客

本文介绍了一个使用ASP.NET和AJAX实现动态加载城市列表的例子。通过下拉列表选择省份后，利用AJAX技术从服务器获取对应城市的HTML表格并显示。涉及的技术包括HTML、JavaScript、ASP.NET及SQL Server数据库操作。

1.建立一个aspx页面，html代码

<title>Untitled Page</title>

var xmlHttp;

function createXMLHttpRequest()

{

if (window.ActiveXObject)

{

xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");

}

else if (window.XMLHttpRequest)

{

xmlHttp = new XMLHttpRequest();

}

function startRequest()

{

//debugger;

var ProvinceID=document.getElementById("DropDownList1");

createXMLHttpRequest();

xmlHttp.onreadystatechange = handleStateChange;

xmlHttp.open("GET", "?ProvinceID="+ProvinceID.value, true);

xmlHttp.send(null);

}

function handleStateChange()

{

if(xmlHttp.readyState == 4) //0(未初始化);1(正在装载);2 (装载完毕);3 (交互中);4 (完成)

{

if(xmlHttp.status == 200) //200(OK);404(not found)

{

document.getElementById("gridiv").innerHTML=xmlHttp.responseText;

}

</script>

</head>

<body>

<div>

<asp:DropDownList ID="DropDownList1" runat="server">

</asp:DropDownList>

</div>

</form>

</body>

</html>

2.cs代码

using System.Data.SqlClient;

protected void Page_Load(object sender, EventArgs e)

{

if (!Page.IsPostBack)

{

this.DropDownList1.Attributes.Add("onchange", "return startRequest();");

ListProvince();

if (ProvinceID != "")

{

GetCityByProvinceID(ProvinceID);

}

#region property

private string ProvinceID

{

get

{

if (Request["ProvinceID"] != null && Request["ProvinceID"].ToString() != "")

{

return Request["ProvinceID"];

}

else

{

return "";

}

#endregion

#region GetDataSet

private DataSet GetDataSet(string sql)

{

string constring=System.Configuration.ConfigurationSettings.AppSettings["ConnectionString"];

SqlDataAdapter sda =new SqlDataAdapter(sql,constring);

DataSet ds=new DataSet();

sda.Fill(ds);

return ds;

}

#endregion

#region GetCityByProvinceID

private void GetCityByProvinceID(string ProvinceID)

{

string connStr = ConfigurationSettings.AppSettings["ConnectionString"];

SqlConnection conn = new SqlConnection(connStr);

string sql = "select * from city where father='" + ProvinceID + "'";

SqlCommand cmd = new SqlCommand(sql, conn);

conn.Open();

SqlDataReader dr = cmd.ExecuteReader();

string s = @"<table cellspacing='0' cellpadding='4' border='0' id='GridView1' style='color:#333333;border-collapse:collapse;'>";

s+="<tr style='color:White;background-color:#990000;font-weight:bold;'>";

s+="<th scope='col'>流水号</th><th scope='col'>代号</th><th scope='col'>城市</th></tr>";

int m = 0;

while (dr.Read())

{

if (m % 2 == 0)

{

s += "<tr style='color:#333333;background-color:#FFFBD6;'>";

}

else

{

s += "<tr style='color:#333333;background-color:White;'>";

}

m++;

s += "<td>" + dr["id"] + "</td>";

s += "<td>" + dr["cityID"] + "</td>";

s += "<td>" + dr["city"] + "</td>";

s += "</tr>";

}

s+="</table>";

dr.Close();

conn.Close();

this.Response.Write(s);

this.Response.End();

}

#endregion

#region ListProvince

private void ListProvince()

{

string sql = "select * from province";

DataSet ds = GetDataSet(sql);

DropDownList1.DataSource = ds;

DropDownList1.DataTextField = "province";

DropDownList1.DataValueField = "provinceID";

DropDownList1.DataBind();

}

#endregion