在Java httpurlconnection请求中获取确切的HTTP Web响应

Question

I am still a bit new to java and what I am having trouble with is handling error responses within an application that accesses an api. I know in .NET you can read the code, inner exception and other details of the error response but not sure in java how to do this. Take the following examples: I am making a general request to the facebook graph API and not getting the expected response in the event of an error response:

        HttpURLConnection conn = (HttpURLConnection) obj.openConnection();
        conn.setRequestMethod("GET");
        conn.setUseCaches(false);
        conn.setRequestProperty("accept-charset", "UTF-8");
        conn.setRequestProperty("content-type", 
       "application/x-www-form-urlencoded");

        //InputStream urlInputStream = conn.getInputStream();

        BufferedReader inSt = new BufferedReader(
          new InputStreamReader(conn.getInputStream()));
        StringBuffer response = new StringBuffer();
        String inputData;

        while((inputData = inSt.readLine()) != null) {

            response.append(inputData);
        }
          ...
            } catch (MalformedURLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
             responseCode = 0;

    } catch (Exception ex) {
        // TODO Auto-generated catch block
        ex.printStackTrace();
        responseCode = 0;
        ResponseText = ex.getMessage().toString();
    }

I thought that printStackTrace would deliver the detailed error message and code but that does not and then getMessage works in some cases.

https://graph.facebook.com/brahmaria

Actual Response:

{
   "error": {
  "message": "Unsupported get request. Please read the 
 Graph API documentation at https://developers.facebook.com/docs/graph-api",
  "type": "GraphMethodException",
  "code": 100
 }
}

The above call returns the error and the following details from ex.getMessage

java.io.IOException: Server returned HTTP response code: 400 for 
 URL:  https://graph.facebook.com/brahmaria

But the next call does not return detailed message:

https://graph.facebook.com/zafdsdkdjdsfs

Actual response:

{
  "error": {
  "message": "(#803) Some of the aliases you requested do not 
   exist:   zafdsdkdjdsfs",
  "type": "OAuthException",
  "code": 803
  }
}

Returns the following without any code:

https://graph.facebook.com/zafdsdkdjdsfs

I need to capture the actual responses with error code in order to handle the exceptions and user responses correctly. Any advice appreciated.

Answer 1

You can't request for user data using their username base, that no longer works in Facebook's Graph version 2.11.

Based on Facebook API Documentation, you need an access token and uses user id instead of username

ie

graph.facebook.com/<user-id>/<resource|optional>&access_token=token