@Controller
public class GetOpenId {

    private static String appid = "";
    private static String appscript = "";
    private static String redirect_uri = "...../getCode";

    @RequestMapping("/getopenid")
    @ResponseBody
    public void getopenid( HttpServletResponse response) {

        String url = "https://open.weixin.qq.com/connect/oauth2/authorize?appid="
                + appid
                + "&redirect_uri="
                + redirect_uri
                + "&response_type=code&scope=snsapi_userinfo&state=1234#wechat_redirect";

        try {
            response.sendRedirect(url);  //重定向跳转到url
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

    @RequestMapping("/getCode")
    @ResponseBody
    public void getCode(String code, String state, HttpServletResponse response) {

        String path = "https://api.weixin.qq.com/sns/oauth2/access_token?";
        String params = "appid=" + appid + "&secret=" + appscript + "&code="
                + code + "&grant_type=authorization_code";

        String parm = Utils.sendPost(path, params);
        JSONObject json = JSONObject.fromObject(parm);
        String openid = json.getString("openid");
        String accessToken = json.getString("access_token");


}