php 把$_POST参数解析出来

if(empty($from)){
echo "<script>parent.alert('广告商为空');parent.document.getElementById('from').focus();</script>";
exit();
}
if(empty($title)){
echo "<script>parent.alert('标题为空');parent.document.getElementById('title').focus();</script>";
exit();
}
if(empty($description)){
echo "<script>parent.alert('描述为空');parent.document.getElementById('description').focus();</script>";
exit();
}