public function postRegister(Request $request){
        $nickname = $request->nickname;
        $mobile = $request->mobile;
        $mail = $request->mail;
        $password = $request->password;
        $repassword = $request->repassword;
        $msg = '';
        if($password == $repassword){

            $user = DB::table('users')->where('mobile',$mobile)->first();
            if($user){
                $msg = '用户已存在！';
            }else{
                $user = array(
                    'nickname'=>$nickname,
                    'mobile'=>$mobile,
                    'email'=>$mail,
                    'password'=>md5($password)
                );
                $ret = DB::table('users')->insert($user);
                if($ret){
                    $msg = '注册成功！';
                    Session::flash('msg',$msg);
                    return redirect('/user/login');
                }else{
                    $msg = '注册失败！';
                }
            }
        }else{
            $msg = '两次输入的密码不一致！';
        }
        Session::flash('msg',$msg);
        return redirect('/user/register');
    }