redirect_uri 参数错误,求解决方案

Question

@WebServlet("/wxLogin")
public class WXLoginServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        String backUrl = "http://morning.iok.la/MEILI/callBack";// 回调地址
        String url = "https://open.weixin.qq.com/connect/oauth2/authorize?appid="
                + AuthUtils.APPID
                + "&redirect_uri="
                + URLEncoder.encode(backUrl)
                + "&response_type=code&scope=snsapi_userinfo&state=STATE#wechat_redirect";
        resp.sendRedirect(url);
    }