public function changepassword()
 {
     if (IS_POST) {
         $password = I('post.password', '');
         $newpassword = I('post.newpassword', '');
         $confirmnewpassword = I('post.confirmnewpassword', '');
         if (strlen($newpassword) < 6 || strlen($newpassword) > 20) {
             $this->ajaxReturn(ReturnValue::faild('密码长度6--20位'));
         }
         if ($newpassword != $confirmnewpassword) {
             $this->ajaxReturn(ReturnValue::faild('两次密码输入不一致'));
         }
         $adminId = BaseController::get_login_userid();
         $admin = M('admin');
         $entity = $admin->find($adminId);
         if ($entity && $entity['password'] == $password) {
             $data['password'] = $newpassword;
             $admin->where('id=' . $adminId)->save($data);
             $this->ajaxReturn(ReturnValue::success("ok"));
         } else {
             $this->ajaxReturn(ReturnValue::faild('密码验证错误!'));
         }
     } else {
         $this->display();
     }
 }