页面开发技巧
1、提交后的回发时能自动进入上次的当前位置
例如,如果数据项导致大型页回发,则最终用户需要将页滚动到此前正在编辑它们的位置,才能继续。页开发人员通过以下方法可以简单地标记窗体,以维持滚动位置:在 @Page
指令中将 MaintainScrollPositionOnPostBack 属性设置为 true,或在 Web.config 中进行此设置,以应用于应用程序中的所有页。
2、Button 控件的 OnClientClick 属性允许您在此按钮被单击时以编程方式运行客户端脚本。该按钮呈现客户端 onclick
属性以及按钮自身的 Javascript。
3、用于控件的一个令人惊喜的新功能是“客户端回调”,该功能允许控件向服务器执行带外请求以获取附加数据,而不发送整页。此功能依赖于用于回调处理(通常通过 XMLHTTP)的浏览器支持,该支持由 SupportsClientCallbacks
在浏览器功能中指定。
其实一般的无刷新页面就可以使用客户端回调来实现,只有复杂的才需要使用AJAX等
<%@ Page Language="C#" AutoEventWireup="true" EnableEventValidation="false" CodeFile="CallBackEventHandler_cs.aspx.cs" Inherits="CallBackEventHandler_cs" %>
<!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>Client CallBack</title>
</head>
<body>
<form id="Form1" runat="server">
<h3>Cascading DropDownLists Using ICallBackEventHandler</h3>
<asp:DropDownList ID="ParentDropDown"
onchange="GetChildren(this.options[this.selectedIndex].value, 'ddl');"
Runat="server">
<asp:ListItem Text="Item 1" />
<asp:ListItem Text="Item 2" />
<asp:ListItem Text="Item 3" />
</asp:DropDownList>
<asp:DropDownList ID="ChildDropDown" AutoPostBack="true" style="visibility:hidden" Runat="Server">
<asp:ListItem Text="Child Item" />
</asp:DropDownList>
<br /><br />
<asp:Label ID="Label1" runat="server"/>
<script type="text/javascript">
function ClientCallback(result, context){
var childDropDown = document.forms[0].elements['<%=ChildDropDown.UniqueID%>'];
if (!childDropDown){
return;
}
childDropDown.length = 0;
if (!result){
return;
}
var rows = result.split('|');
for (var i = 0; i < rows.length; ++i){
var option = document.createElement("OPTION");
option.value = rows[i];
option.innerHTML = rows[i];
childDropDown.appendChild(option);
}
childDropDown.style.visibility = "visible";
}
function ClientCallbackError(result, context){
alert(result);
}
</script>
</form>
</body>
</html>
<!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>Client CallBack</title>
</head>
<body>
<form id="Form1" runat="server">
<h3>Cascading DropDownLists Using ICallBackEventHandler</h3>
<asp:DropDownList ID="ParentDropDown"
onchange="GetChildren(this.options[this.selectedIndex].value, 'ddl');"
Runat="server">
<asp:ListItem Text="Item 1" />
<asp:ListItem Text="Item 2" />
<asp:ListItem Text="Item 3" />
</asp:DropDownList>
<asp:DropDownList ID="ChildDropDown" AutoPostBack="true" style="visibility:hidden" Runat="Server">
<asp:ListItem Text="Child Item" />
</asp:DropDownList>
<br /><br />
<asp:Label ID="Label1" runat="server"/>
<script type="text/javascript">
function ClientCallback(result, context){
var childDropDown = document.forms[0].elements['<%=ChildDropDown.UniqueID%>'];
if (!childDropDown){
return;
}
childDropDown.length = 0;
if (!result){
return;
}
var rows = result.split('|');
for (var i = 0; i < rows.length; ++i){
var option = document.createElement("OPTION");
option.value = rows[i];
option.innerHTML = rows[i];
childDropDown.appendChild(option);
}
childDropDown.style.visibility = "visible";
}
function ClientCallbackError(result, context){
alert(result);
}
</script>
</form>
</body>
</html>
//-----------------------------------------------------------------------
// This file is part of the Microsoft .NET SDK Code Samples.
//
// Copyright (C) Microsoft Corporation. All rights reserved.
//
//This source code is intended only as a supplement to Microsoft
//Development Tools and/or on-line documentation. See these other
//materials for detailed information regarding Microsoft code samples.
//
//THIS CODE AND INFORMATION ARE PROVIDED AS IS WITHOUT WARRANTY OF ANY
//KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
//IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
//PARTICULAR PURPOSE.
//-----------------------------------------------------------------------
using System;
using System.Web.UI;
public partial class CallBackEventHandler_cs : System.Web.UI.Page, ICallbackEventHandler
{
private string _callbackResult;
private void Page_Load(object source, EventArgs e)
{
String callBack = Page.ClientScript.GetCallbackEventReference(this, "arg", "ClientCallback", "context", "ClientCallbackError", false);
String clientFunction = "function GetChildren(arg, context){ " + callBack + "; }";
Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "GetChildren", clientFunction, true);
if (Page.IsPostBack && !Page.IsCallback)
{
Label1.Text = "You Selected: " + Request.Form["ParentDropDown"] + ": " + Request.Form["ChildDropDown"];
}
}
public string GetCallbackResult()
{
return _callbackResult;
}
public void RaiseCallbackEvent(string eventArgument)
{
switch (eventArgument)
{
case "Item 1":
_callbackResult = "One|Two|Three";
break;
case "Item 2":
_callbackResult = "Four|Five|Six";
break;
case "Item 3":
_callbackResult = "Seven|Eight|Nine";
break;
default:
_callbackResult = "";
break;
}
}
}
// This file is part of the Microsoft .NET SDK Code Samples.
//
// Copyright (C) Microsoft Corporation. All rights reserved.
//
//This source code is intended only as a supplement to Microsoft
//Development Tools and/or on-line documentation. See these other
//materials for detailed information regarding Microsoft code samples.
//
//THIS CODE AND INFORMATION ARE PROVIDED AS IS WITHOUT WARRANTY OF ANY
//KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
//IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
//PARTICULAR PURPOSE.
//-----------------------------------------------------------------------
using System;
using System.Web.UI;
public partial class CallBackEventHandler_cs : System.Web.UI.Page, ICallbackEventHandler
{
private string _callbackResult;
private void Page_Load(object source, EventArgs e)
{
String callBack = Page.ClientScript.GetCallbackEventReference(this, "arg", "ClientCallback", "context", "ClientCallbackError", false);
String clientFunction = "function GetChildren(arg, context){ " + callBack + "; }";
Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "GetChildren", clientFunction, true);
if (Page.IsPostBack && !Page.IsCallback)
{
Label1.Text = "You Selected: " + Request.Form["ParentDropDown"] + ": " + Request.Form["ChildDropDown"];
}
}
public string GetCallbackResult()
{
return _callbackResult;
}
public void RaiseCallbackEvent(string eventArgument)
{
switch (eventArgument)
{
case "Item 1":
_callbackResult = "One|Two|Three";
break;
case "Item 2":
_callbackResult = "Four|Five|Six";
break;
case "Item 3":
_callbackResult = "Seven|Eight|Nine";
break;
default:
_callbackResult = "";
break;
}
}
}