public interface WeChatAuthService extends AuthService {
 public JSONObject getUserInfo(String accessToken, String openId);
}

@Service
public class WeChatAuthServiceImpl extends DefaultAuthServiceImpl implements WeChatAuthService {

 private Logger logger = LoggerFactory.getLogger(WeChatAuthServiceImpl.class);

//請求此地址即跳轉到二維碼登錄界面
 private static final String AUTHORIZATION_URL =
   "https://open.weixin.qq.com/connect/qrconnect?appid=%s&redirect_uri=%s&response_type=code&scope=%s&state=%s#wechat_redirect";

 // 獲取用戶 openid 和access——toke 的 URL
 private static final String ACCESSTOKE_OPENID_URL =
   "https://api.weixin.qq.com/sns/oauth2/access_token?appid=%s&secret=%s&code=%s&grant_type=authorization_code";

 private static final String REFRESH_TOKEN_URL =
   "https://api.weixin.qq.com/sns/oauth2/refresh_token?appid=%s&grant_type=refresh_token&refresh_token=%s";

 private static final String USER_INFO_URL =
   "https://api.weixin.qq.com/sns/userinfo?access_token=%s&openid=%s&lang=zh_CN";

 private static final String APP_ID="xxxxxx";
 private static final String APP_SECRET="xxxxxx";
 private static final String SCOPE = "snsapi_login";

 private String callbackUrl = "https://www.xxx.cn/auth/wechat"; //回調域名

 @Override
 public String getAuthorizationUrl() throws UnsupportedEncodingException {
  callbackUrl = URLEncoder.encode(callbackUrl,"utf-8");
  String url = String.format(AUTHORIZATION_URL,APP_ID,callbackUrl,SCOPE,System.currentTimeMillis());
  return url;
 }


 @Override
 public String getAccessToken(String code) {
  String url = String.format(ACCESSTOKE_OPENID_URL,APP_ID,APP_SECRET,code);

  UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(url);
  URI uri = builder.build().encode().toUri();

  String resp = getRestTemplate().getForObject(uri, String.class);
  logger.error("getAccessToken resp = "+resp);
  if(resp.contains("openid")){
   JSONObject jsonObject = JSONObject.parseObject(resp);
   String access_token = jsonObject.getString("access_token");
   String openId = jsonObject.getString("openid");;

   JSONObject res = new JSONObject();
   res.put("access_token",access_token);
   res.put("openId",openId);
   res.put("refresh_token",jsonObject.getString("refresh_token"));

   return res.toJSONString();
  }else{
   throw new ServiceException("獲取token失敗，msg = "+resp);
  }
 }

 //微信接口中，token和openId是一起返回，故此方法不需實現(xiàn)
 @Override
 public String getOpenId(String accessToken) {
  return null;
 }

 @Override
 public JSONObject getUserInfo(String accessToken, String openId){
  String url = String.format(USER_INFO_URL, accessToken, openId);
  UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(url);
  URI uri = builder.build().encode().toUri();

  String resp = getRestTemplate().getForObject(uri, String.class);
  logger.error("getUserInfo resp = "+resp);
  if(resp.contains("errcode")){
   throw new ServiceException("獲取用戶信息錯誤，msg = "+resp);
  }else{
   JSONObject data =JSONObject.parseObject(resp);

   JSONObject result = new JSONObject();
   result.put("id",data.getString("unionid"));
   result.put("nickName",data.getString("nickname"));
   result.put("avatar",data.getString("headimgurl"));

   return result;
  }
 }

 //微信的token只有2小時的有效期，過時需要重新獲取，所以官方提供了
 //根據(jù)refresh_token 刷新獲取token的方法，本項目僅僅是獲取用戶
 //信息，并將信息存入庫，所以兩個小時也已經(jīng)足夠了
 @Override
 public String refreshToken(String refresh_token) {

  String url = String.format(REFRESH_TOKEN_URL,APP_ID,refresh_token);

  UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(url);
  URI uri = builder.build().encode().toUri();

  ResponseEntity<JSONObject> resp = getRestTemplate().getForEntity(uri,JSONObject.class);
  JSONObject jsonObject = resp.getBody();

  String access_token = jsonObject.getString("access_token");
  return access_token;
 }
}

@RequestMapping(value = "/wxLoginPage",method = RequestMethod.GET)
 public JSONObject wxLoginPage() throws Exception {
  String uri = weChatAuthService.getAuthorizationUrl();
  return loginPage(uri);
 }

 @RequestMapping(value = "/wechat")
 public void callback(String code,HttpServletRequest request,HttpServletResponse response) throws Exception {
  String result = weChatAuthService.getAccessToken(code);
  JSONObject jsonObject = JSONObject.parseObject(result);

  String access_token = jsonObject.getString("access_token");
  String openId = jsonObject.getString("openId");
//  String refresh_token = jsonObject.getString("refresh_token");

  // 保存 access_token 到 cookie，兩小時過期
  Cookie accessTokencookie = new Cookie("accessToken", access_token);
  accessTokencookie.setMaxAge(60 *2);
  response.addCookie(accessTokencookie);

  Cookie openIdCookie = new Cookie("openId", openId);
  openIdCookie.setMaxAge(60 *2);
  response.addCookie(openIdCookie);

  //根據(jù)openId判斷用戶是否已經(jīng)登陸過
  KmsUser user = userService.getUserByCondition(openId);

  if (user == null) {
   response.sendRedirect(request.getContextPath() + "/student/html/index.min.html#/bind?type="+Constants.LOGIN_TYPE_WECHAT);
  } else {
   //如果用戶已存在，則直接登錄
   response.sendRedirect(request.getContextPath() + "/student/html/index.min.html#/app/home?open_id=" + openId);
  }
 }