Question

我正在开发一个使用Facebook Graph Api来收集有关公共帖子的信息的项目。当更改发布到此帖子时，需要实时更新此数据。我已经看到使用回调网址https://developers.facebook.com/docs/graph-api/reference/app/subscriptions/和https://developers.facebook.com/docs/graph-api/real-time-updates/的实时更新机制..但我不知道在java中这样做。请有人帮我使用一个例子。

Answer 1

页面和用户对象可以使用实时更新。它们都需要相应页面或用户的访问令牌。（对于页面，您可以使用我/帐户进行检查，或通过为您的应用授予页面访问权限来获取它）。

步骤1：您将需要一个公共IP，Facebook将发布更新。第2步：您需要设置您的fb应用程序以启动实时更新设置

  String appId = //your app id
  String token = //app token appId|appSecret
  String callbackUrl = //your public url
  PostMethod method = new PostMethod();
  method.setURI(new URI("https://graph.facebook.com/" + appId +
           "/subscriptions?callback_url=" + callbackUrl +
         "&object=page&fields=feed&verify_token=streamInit&method=POST&access_token="+
           token, false));

  HttpClient httpClient = new HttpClient();
  if (method != null) {
        int statusCode = httpClient.executeMethod(method);
        String response = new String(method.getResponseBody());
        if (statusCode == HttpStatus.SC_OK) {

                 //Completed streaming initiation
        }else{
           //Streaming initialization failed"
        }
     }
  } catch (Exception e) {

  }

步骤3：这将触发facebook回调网址验证。它可以是一个servlet或任何其他将处理发布到回调url.Facebook的更新将在需要重新发送的get请求中提供挑战代码。

 protected void doGet(HttpServletRequest request, HttpServletResponse response)
  throws ServletException, IOException {
  Map parametersMap = request.getParameterMap();
  if (parametersMap.size() > 0) {
     if (request.getParameter("hub.mode").equals("streamInit")) {
        System.out.println("Verify Token: " + request.getParameter("hub.verify_token"));
        System.out.println("Challenge number:" + request.getParameter("hub.challenge"));

        String responseToClient = request.getParameter("hub.challenge");
        response.setStatus(HttpServletResponse.SC_OK);
        response.getWriter().write(responseToClient);
        response.getWriter().flush();
        response.getWriter().close();

           //"Completed streaming setup on your url" 
     }
  }

}

步骤3：将您的应用程序添加为页面选项卡，以便从该页面的实时更新中进行订阅。您将需要一个页面访问令牌

  String appId = //your application id
  String pageId=//page id to subscribe from
  PostMethod method =
        new PostMethod("https://graph.facebook.com/" + pageId + "/tabs?app_id=" + appId +
              "&method=POST&access_token=" + pageToken);
  HttpClient httpClient = new HttpClient();
  try {
     int statusCode = httpClient.executeMethod(method);
     String response = new String(method.getResponseBody());
     if (statusCode == HttpStatus.SC_OK) {

        // "Completed tab addition"
     }else{
        // "Tab adding failed"
     }

  } catch (Exception e) {
     //"Tab adding failed" 
  }

第4步：Facebook将通过发布请求将更新发布到您的回拨网址。

facebook实例更新java示例

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