access_token是调用授权关系接口的调用凭证，由于access_token有效期（目前为2个小时）较短，当access_token超时后，可以使用refresh_token进行刷新，access_token刷新结果有两种：
1.若access_token已超时，那么进行refresh_token会获取一个新的access_token，新的超时时间；
2.若access_token未超时，那么进行refresh_token不会改变access_token，但超时时间会刷新，相当于续期access_token。
刷新token
private void refreshAccessToken() { String uri = "https://api.weixin.qq.com/sns/oauth2/refresh_token?appid=" + ShareUtil.APP_ID + "&grant_type=refresh_token&refresh_token=" + refreshToken; HttpClient client = new DefaultHttpClient(); HttpGet get = new HttpGet(URI.create(uri)); try { HttpResponse response = client.execute(get); if (response.getStatusLine().getStatusCode() == 200) { BufferedReader reader = new BufferedReader(new InputStreamReader(response.getEntity().getContent(), "UTF-8")); StringBuilder builder = new StringBuilder(); for (String temp = reader.readLine(); temp != null; temp = reader.readLine()) { builder.append(temp); } JSONObject object = new JSONObject(builder.toString().trim()); accessToken = object.getString("access_token"); refreshToken = object.getString("refresh_token"); openID = object.getString("openid"); expires_in = object.getLong("expires_in"); } } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } }
正确的返回：
{ "access_token":"ACCESS_TOKEN", "expires_in":7200, "refresh_token":"REFRESH_TOKEN", "openid":"OPENID", "scope":"SCOPE" }
参数 说明
access_token 接口调用凭证
expires_in access_token接口调用凭证超时时间，单位（秒）
refresh_token 用户刷新access_token
openid 授权用户唯一标识
scope 用户授权的作用域，使用逗号（,）分隔
错误返回样例：
{ "errcode":40030,"errmsg":"invalid refresh_token" }