dopostback提交表单

dopostback提交表单
原网页的表单如下：
[color=008000]<form name="Form1" method="post" action="Default.aspx" id="Form1" target="_parent">
<input type="hidden" name="__EVENTTARGET" value="" />
<input type="hidden" name="__EVENTARGUMENT" value="" />
<input type="hidden" name="__VIEWSTATE" value="dDwtMzU5MDE2Nzc1O3Q8O2w8aTwwPjtpPDE+Oz47bDx0PDtsPGk8MT47PjtsPHQ8cDxsPHNyYzs+O2w8aHR0cDovL2ltZzEuc291ZnVuLmNvbS9tbHMvaW1hZ2UvbmV3bWxzL2RlbmdsdS5qcGc7Pj47Oz47Pj47dDxwPHA8bDxUZXh0Oz47bDxcPGZvbnQgc2l6ZT0yIGNvbG9yPXJlZFw+6aqM6K+B56CB5Ye66ZSZ77yBXDwvZm9udFw+Oz4+Oz47Oz47Pj47bDxTdWJfTG9naW47Pj4=" />

<script language="javascript" type="text/javascript">
<!--
function __doPostBack(eventTarget, eventArgument) {
var theform;
if (window.navigator.appName.toLowerCase().indexOf("microsoft") > -1) {
theform = document.Form1;
}
else {
theform = document.forms["Form1"];
}
theform.__EVENTTARGET.value = eventTarget.split("$").join(":");
theform.__EVENTARGUMENT.value = eventArgument;
theform.submit();
}
// -->
</script>

<TBODY>
<TR><TD><input name="managername" id="managername" type="text" style="WIDTH: 70px" tabIndex="2" maxlength="20" size="10" value="" /></TD>

<TD rowSpan="2"><input src="http://**denglu.jpg" name="Sub_Login" id="Sub_Login" type="image" tabIndex="5" height="42" width="49" /></TD>

<TR><TD><input name="passwd" id="passwd" type="password" style="WIDTH: 70px" tabIndex="3" maxlength="20" size="10" /></TD></TR>

<TR><input name="verifycode" id="verifycode" type="text" style="WIDTH: 70px" tabIndex="4" maxlength="4" size="10" value="" /></TD>

<TD><IMG height="22" src="CheckImg.aspx" width="59"></TD></TR>

</TBODY></form>[/color]

自己写的如下

[color=red]use strict;
use warnings;
use LWP;
use HTTP::Cookies;
use LWP::Simple;

my $browser=LWP::UserAgent->new;
my $new_agent='Mozilla/5.0';
$browser->agent($new_agent);
my $response;
$browser->cookie_jar(HTTP::Cookies->new(
'file'=>'SHOUFUN',
'autosave'=>1));

my $url='http://m**.com/Default.aspx'; #浏览提交的网页
$response=$browser->get($url);
push @{$browser->requests_redirectable},"POST";

my $post_url='http://m**.Default.aspx'; #表单POST提交URL
my $img_url='http://m**.com/CheckImg.aspx'; #图片URL

my $viewstate;
my $content=$response->content;
if ($content=~'.*VIEWSTATE" value="(.*)".\/') {
$viewstate=$1;
}
print $viewstate;
print "\r\nstore img\r\n";
getstore($img_url,'CheckImg.JPG');

print "\r\nNum \r\n";
my $check;
$check=<STDIN>;
chomp $check;
print $check;
sleep 2;
$response=$browser->post($post_url,
[
"__EVENTTARGET"=> '',
"__EVENTARGUMENT"=>'',
"__VIEWSTATE'"=>$viewstate,
'managername'=>'',
'passwd'=>'',
'verifycode'=>$check,
'Sub_Login'=>'Sub_Login'
]
);

print $response->content;[/color]


不知道 [color=red]"__EVENTTARGET[/color] 与[color=red]__EVENTARGUMENT[/color]这两个变量怎么获取，怎么提交请指点一下，谢谢！