{
  // send oauth request 
   Final SendAuth.Req req = new SendAuth.Req();
   req.scope = "snsapi_userinfo";
   req.state = "wechat_sdk_demo_test";
   api.sendReq(req);
}

@Override
public void onResp(BaseResp resp) {
  int errorCode = resp.errCode;
  switch (errorCode) {
  case BaseResp.ErrCode.ERR_OK:
    //用户同意
    String code = ((SendAuth.Resp) resp).code;
    break;
  case BaseResp.ErrCode.ERR_AUTH_DENIED:
    //用户拒绝
    break;
  case BaseResp.ErrCode.ERR_USER_CANCEL:
    //用户取消
    break;
  default:
    break;
  }
  ToastUtil.showMessageLong(this, resp.errStr);
}

private String getAccessToken(String code) {
    String url = "https://api.weixin.qq.com/sns/oauth2/access_token?appid=APPID&secret=SECRET&code=CODE&grant_type=authorization_code";
    URI uri = URI.create(url);
    HttpClient client = new DefaultHttpClient();
    HttpGet get = new HttpGet(uri);
    HttpResponse response;
  try {
    response = client.execute(get);
    if (response.getStatusLine().getStatusCode() == 200) {
      HttpEntity entity = response.getEntity();

      BufferedReader reader = new BufferedReader(new InputStreamReader(entity.getContent(), "UTF-8"));
      StringBuilder sb = new StringBuilder();

      for (String temp = reader.readLine(); temp != null; temp = reader.readLine()) {
        sb.append(temp);
      }

      JSONObject object = new JSONObject(sb.toString().trim());
      accessToken = object.getString("access_token");
      openID = object.getString("openid");
      refreshToken = object.getString("refresh_token");
      expires_in = object.getLong("expires_in");
      return accessToken;
    }
  } catch (Exception e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
  }
  return null;
}

{ 
"access_token":"ACCESS_TOKEN", 
"expires_in":7200, 
"refresh_token":"REFRESH_TOKEN",
"openid":"OPENID", 
"scope":"SCOPE",
"unionid":"o6_bmasdasdsad6_2sgVt7hMZOPfL"
}

{"errcode":40029,"errmsg":"invalid code"}

private void getUserInfo() {
    if (isAccessTokenIsInvalid() && System.currentTimeMillis() < expires_in) {
      String uri = "https://api.weixin.qq.com/sns/userinfo?access_token=" + accessToken + "&openid=" + openID;
      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());
          String nikeName = object.getString("nickname");
        }
      } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }
    }
  }

private boolean isAccessTokenIsInvalid() {
    String url = "https://api.weixin.qq.com/sns/auth?access_token=" + accessToken + "&openid=" + openID;
    URI uri = URI.create(url);
    HttpClient client = new DefaultHttpClient();
    HttpGet get = new HttpGet(uri);
    HttpResponse response;
    try {
      response = client.execute(get);
      if (response.getStatusLine().getStatusCode() == 200) {
        HttpEntity entity = response.getEntity();
      BufferedReader reader = new BufferedReader(new InputStreamReader(entity.getContent(), "UTF-8"));
      StringBuilder sb = new StringBuilder();

      for (String temp = reader.readLine(); temp != null; temp = reader.readLine()) {
        sb.append(temp);
      }
      JSONObject object = new JSONObject(sb.toString().trim());
      int errorCode = object.getInt("errcode");
      if (errorCode == 0) {
        return true;
      }
    }
  } catch (Exception e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
  }
  return false;
}

  { 
  "errcode":0,"errmsg":"ok"
  }

  { 
  "errcode":40003,"errmsg":"invalid openid"
  }

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();
  }
}

{ 
"access_token":"ACCESS_TOKEN", 
"expires_in":7200, 
"refresh_token":"REFRESH_TOKEN", 
"openid":"OPENID", 
"scope":"SCOPE" 
}

{
"errcode":40030,"errmsg":"invalid refresh_token"
}