一、鼠标滑过textbox全选

前台：

<asp:TextBox runat="server" onMouseOver="this.focus();this.select()">dsdsds</asp:TextBox>

或

<asp:TextBox runat="server" onMouseOver="this.focus()" onFocus="this.select()">dsdsds</asp:TextBox>

后台：

this.txtbox1.Attributes.Add("onMouseOver", "this.focus();this.select();");

二、得到焦点

后台：

textbox1.Focus();

textbox1.Attributes.Add("onfocus","this.select()");