再一次如果您使用的是文件上载，则它与图像上载不同。要获取文件url，请使用：$（html）。属性（\'href\'）；

文件上载：

window.send_to_editor = function(html){
    var file_url = $(html).attr(\'href\');

    // Do something with those variables

    tb_remove();
};

window.send_to_editor = function(html){
    var file_url = $(\'img\', html).attr(\'src\'),
        classes  = $(\'img\', html).attr(\'class\'),
        id       = classes.replace(/(.*?)wp-image-/, \'\');

    // Do something with those variables

    tb_remove();
};

try this:

window.send_to_editor = function(html){
    dlink = jQuery(\'img\',html).attr(\'src\');
    jQuery(\'#download_link\').val(dlink);
    tb_remove();
}

<div>
    <label style="float:left; margin: 5px 5px 0 0;">Image 4:</label>
    <input type="text" id="image_4" name="image_4" value="" style="width: 550px; float:left; margin:0 5px;"/>
    <input id="_btn" class="upload_image_button" type="button" value="Upload Image" />
    <input type="hidden" name="image4_id" id="image4_id" value="<?php echo $image_id4; ?>" />
</div>

<script>
jQuery(document).ready(function () {
    var formfield;
    var id;
    jQuery(\'.upload_image_button\').click(function () {
        jQuery(\'html\').addClass(\'Image\');
        formfield = jQuery(this).prev().attr(\'name\');
        id = jQuery(this).next().attr(\'name\');

        tb_show(\'\', \'media-upload.php?type=image&amp;TB_iframe=true\');
        return false;
    });
    window.original_send_to_editor = window.send_to_editor;
    window.send_to_editor = function (html) {
        if (formfield) {
            fileurl = jQuery(\'img\', html).attr(\'src\');
            jQuery(\'#\' + formfield).val(fileurl);

            imgclass = jQuery(\'img\', html).attr(\'class\');
            imgid = parseInt(imgclass.replace(/\\D/g, \'\'), 10);
            jQuery(\'#\' + id).val(imgid);

            tb_remove();
            jQuery(\'html\').removeClass(\'Image\');
        } else {
            window.original_send_to_editor(html);
        }
    };
});
</script>