Ajax

前台：添加ScriptManager，UpdatePanel，在UpdatePanel中加入2个Label，2个TextBox，2个Button.

<form id="form1" runat="server">
    <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label>

    <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox>
    <asp:Button ID="Button2" runat="server" onclick="Button2_Click" 
        style="height: 21px" Text="Button" />

    <div>
        <asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
                <asp:Label ID="Label2" runat="server" Text="Label"></asp:Label>
                <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
                <asp:Button ID="Button1" runat="server" onclick="Button1_Click" Text="Button" />
            </ContentTemplate>
            


        </asp:UpdatePanel>

    </div>
    </form>

后台

protected void Page_Load(object sender, EventArgs e)
        {
            Label1.Text = DateTime.Now.ToString();

        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            TextBox1.Text = DateTime.Now.ToString();

        }

        protected void Button2_Click(object sender, EventArgs e)
        {
            TextBox2.Text = DateTime.Now.ToString();
        }
    }

可以观察到Button1单击完成局部更新（Label1没有变化），单击Button2后，Page_Load事件触发。