无刷新上传图片

前端页面:

<script type="text/javascript" src="../../js/jquery-1.3.2.min.js"></script>
<script type="text/javascript" src="scripts/jquery.form.js"></script>

<script type="text/javascript" >
 $(document).ready(function() {

            $('#photoimg').live('change', function()            {
                       $("#preview").html('');
                $("#preview").html('<img src="loader.gif" alt="Uploading...."/>');
            $("#imageform").ajaxForm({
                        target: '#preview'
        }).submit();

            });
        });
</script>
<div style="width:600px">

<form id="imageform" method="post" enctype="multipart/form-data" action='ajaximage.php'>
上传 <input type="file" name="photoimg" id="photoimg" />
</form>
<div id='preview'>
</div>


</div>

后端:

$path = "../upload/";

    $valid_formats = array("jpg", "png", "gif", "bmp");
    if(isset($_POST) and $_SERVER['REQUEST_METHOD'] == "POST")
        {
            $name = $_FILES['photoimg']['name'];
            $size = $_FILES['photoimg']['size'];

            if(strlen($name))
                {
                    list($txt, $ext) = explode(".", $name);
                    if(in_array($ext,$valid_formats))
                    {
                    if($size<(1024*1024))
                        {
                            $actual_image_name = time().substr(str_replace(" ", "_", $txt), 5).".".$ext;
                            $tmp = $_FILES['photoimg']['tmp_name'];
                            if(move_uploaded_file($tmp, $path.$actual_image_name))
                                {


                                    echo "<img src='../upload/".$actual_image_name."'  class='preview'>";
                                }
                            else
                                echo "failed";
                        }
                        else
                        echo "Image file size max 1 MB";
                        }
                        else
                        echo "Invalid file format..";
                }

            else
                echo "Please select image..!";

            exit;
        }