学了那么久ASP.NET一直没有学习__doPsotBack 现在补上,扫扫盲
ASPX页面有包含asp:LinkButton或者带有AutoPostBack属性且其值为true的服务器控件时,ASP.NET会自动为页面生成下面的脚本:
<input type="hidden" name="__EVENTTARGET" id="__EVENTTARGET" value="" />
<input type="hidden" name="__EVENTARGUMENT" id="__EVENTARGUMENT" value="" />
function __doPostBack(eventTarget, eventArgument) {
if(!theForm.onsubmit || (theForm.onsubmit() != false)) {
theForm.__EVENTTARGET.value = eventTarget;
theForm.__EVENTARGUMENT.value = eventArgument;
theForm.submit();
}
}
<input type="hidden" name="__EVENTARGUMENT" id="__EVENTARGUMENT" value="" />
function __doPostBack(eventTarget, eventArgument) {
if(!theForm.onsubmit || (theForm.onsubmit() != false)) {
theForm.__EVENTTARGET.value = eventTarget;
theForm.__EVENTARGUMENT.value = eventArgument;
theForm.submit();
}
}
__doPostBack带有两个参数:eventTarget和eventArgument。
eventTarget是引起回送的控件的ID,eventArgument是回调参数(与控件相关的附加数据)。这两个参数分别由隐藏的两个表单域__ EVENTTARGET和__ EVENTARGUMENT保存。
使用这两个隐藏的表单可以查找引起页面回送的控件ID和回送时的参数:
protected void Page_Load(object sender, EventArgs e)
{
string target = Request.Params["__EVENTTARGET"];
string args = Request.Params["__EVENTARGUMENT"];
}
{
string target = Request.Params["__EVENTTARGET"];
string args = Request.Params["__EVENTARGUMENT"];
}
因为asp:Button和asp:ImageButton不是使用__doPostBack回送页面,所以使用这两个控件回送页面时,上面的代码是无效的。
使用HTML控件回送页面:
<form id="form1" runat="server">
<asp:LinkButton ID="LinkButton1" runat="server"></asp:LinkButton>
<input type="button" value="Client Control" onclick="javascript:__doPostBack(’Button1’, ’Button Click’);" />
</form>
protected void Page_Load(object sender, EventArgs e)
{
if(this.IsPostBack)
{
string target = Request.Params["__EVENTTARGET"];
string args = Request.Params["__EVENTARGUMENT"];
Response.Write("Button ID: " + target + "<br />");
Response.Write("Arguments: " + args + "<br />");
}
}
<asp:LinkButton ID="LinkButton1" runat="server"></asp:LinkButton>
<input type="button" value="Client Control" onclick="javascript:__doPostBack(’Button1’, ’Button Click’);" />
</form>
protected void Page_Load(object sender, EventArgs e)
{
if(this.IsPostBack)
{
string target = Request.Params["__EVENTTARGET"];
string args = Request.Params["__EVENTARGUMENT"];
Response.Write("Button ID: " + target + "<br />");
Response.Write("Arguments: " + args + "<br />");
}
}
加入的目的是为了让ASPX自动生成__doPostBack脚本。
阻止asp:Button提交页面:
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)