以下代码如何实现上传头像？

html:
<img src="{$user.face}" />
<dt style=" height:47px; line-height:47px;">上传头像：</dt>
<input type="hidden" name="path" id="path" />
js:
调不通？？？？？
PHP后端：
public function avatar(){
$uid = get_cookie('uid');
$user = M('member')->find($uid);
if (IS_POST) {
$path = I('path', '', 'trim');
$data['face'] = $path;
$data['id'] = $uid;
if (empty($data['face'])) {
$this->error('请上传图片！');
}
if (M('member')->save($data) !== false) {
//$this->success('保存成功',U('Member/avatar'));
$this->redirect('Member/avatar');
}
exit();
}
$this->assign('user', $user);
$this->assign('uid', $uid);
$this->assign('title', '头像设置');
$this->display();
}
public function saveavater(){
$uid = intval(get_cookie('uid'));
$rs = array();
//上传切头像
$input = file_get_contents('php://input');
$data = explode('--------------------', $input);
$url = './uploads/avatar';
$file = '/'.$uid.'.jpg';
if (!file_exists($url)){
mkdir($url);
}
@file_put_contents($url.$file, $data[0]);
$rs['status'] = $url.$file;
$this->ajaxReturn($rs);
}