log.fine("-- processing exchangeToken --");
req.setCharacterEncoding("UTF-8");
resp.setContentType("text/html;charset=UTF-8");
WeiboSource source = WeiboSource.valueOf(req.getParameter("weibo_source"));
String oauth_token = req.getParameter("oauth_token");
String oauth_verifier = req.getParameter("oauth_verifier");
AuthToken authToken = this.authTokenDao.getByToken(oauth_token);
switch (source) {