.net之QueryString
asp.net中有四大跨页面传值的方法，利用QueryString是最简单的一种。
关于QueryString 有以下几个记忆点：
1.QueryString所传的值必须在2K以内，2K包括url地址
2.获取信息的形式只能是一个字符串
3.页面跳转同时存在Sever.Transfer和Response.Redirect时可能会存在bug
4.调用不存的参数的返回值，返回的是null，而不是空字符串
5,在保证与其他参数不会重名的时候，可以简略写成Request["paraname"];
以下是针对上面各点的小程序：
Default.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="_Default" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
静态链接传值：<br />
<a href="Default2.aspx?id=123">
ID=123</a></div>
<p>
控件传值：</p>
<p>
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:Button ID="Button1" runat="server" Text="发送" onclick="Button1_Click" />
</p>
<p>
checkbox传值：</p>
<p>
<asp:CheckBox ID="CheckBox1" runat="server"
oncheckedchanged="CheckBox1_CheckedChanged" AutoPostBack="true" />
</p>
<p>
传多个值：<asp:DropDownList ID="DropDownList1" runat="server">
<asp:ListItem>阿里</asp:ListItem>
<asp:ListItem>小米</asp:ListItem>
<asp:ListItem>百度</asp:ListItem>
</asp:DropDownList>
<asp:DropDownList ID="DropDownList2" runat="server">
<asp:ListItem>马云</asp:ListItem>
<asp:ListItem>李彦宏</asp:ListItem>
<asp:ListItem>雷军</asp:ListItem>
</asp:DropDownList>
<asp:Button ID="Button2" runat="server" Text="发送" onclick="Button2_Click" />
</p>
</form>
</body>
</html>
Default.aspx.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void Button1_Click(object sender, EventArgs e)
{
string name_url;
name_url = "Default2.aspx?name=" + TextBox1.Text;
Response.Redirect(name_url);
}
protected void CheckBox1_CheckedChanged(object sender, EventArgs e)
{
string _chk = CheckBox1.Checked.ToString();
string _url = "Default2.aspx?_chk=" + _chk;
Server.Transfer(_url);
}
protected void Button2_Click(object sender, EventArgs e)
{
string _name = DropDownList2.SelectedItem.Text;
string _website = DropDownList1.SelectedItem.Text;
string _url = "Default2.aspx?_name=" + _name + "&_website=" + _website;
Response.Redirect(_url);
}
}
Default2.aspx
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
接受静态链接的传值：<asp:Label ID="Label1" runat="server" Text=""></asp:Label>
</div>
<p>
接收控件传值：<asp:Label ID="Label2" runat="server" Text=""></asp:Label>
</p>
<p>
接收checkbox的传值：<asp:Label ID="Label3" runat="server" Text=""></asp:Label>
</p>
<p>
接收多个传值：<asp:Label ID="Label4" runat="server" Text=""></asp:Label>
<asp:Label ID="Label5" runat="server" Text=""></asp:Label>
</p>
</form>
</body>
</html>
Default2.aspx.cs
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class Default2 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
Label1.Text = Request.QueryString["id"];
Label2.Text = Request.QueryString["name"];
Label3.Text = Request.QueryString["_chk"];
Label4.Text = Request.QueryString["_name"];
Label5.Text = Request.QueryString["_website"];
}
}