Java tutorial
/* Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. */ package edu.pdx.its.portal.routelandia; import android.os.AsyncTask; import android.util.Log; import com.google.android.gms.maps.model.LatLng; import org.apache.http.HttpResponse; import org.apache.http.client.HttpClient; import org.apache.http.client.methods.HttpPost; import org.apache.http.entity.ByteArrayEntity; import org.apache.http.entity.StringEntity; import org.apache.http.impl.client.DefaultHttpClient; import org.apache.http.message.BasicHeader; import org.apache.http.protocol.HTTP; import org.apache.http.util.EntityUtils; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import org.json.JSONTokener; import java.io.BufferedReader; import java.io.IOException; import java.io.InputStream; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.concurrent.ExecutionException; import edu.pdx.its.portal.routelandia.entities.APIException; import edu.pdx.its.portal.routelandia.entities.APIPostWrapper; import edu.pdx.its.portal.routelandia.entities.APIResultWrapper; import edu.pdx.its.portal.routelandia.entities.TrafficStat; /** * Takes an API Postable and returns the result of the POST operation. * * Created by loc on 1/30/15. */ public class ApiPoster<T> extends AsyncTask<APIPostWrapper, Void, APIResultWrapper> { private final String TAG = "APIPoster"; private AsyncResult delegate; private String callback_tag; private Class<T> target_class; private APIResultWrapper.ResultType result_type; public ApiPoster(AsyncResult d, String callback_tag, Class<T> klass, APIResultWrapper.ResultType rt) { this.delegate = d; this.callback_tag = callback_tag; this.target_class = klass; this.result_type = rt; } @Override protected APIResultWrapper doInBackground(APIPostWrapper... params) { // Foolishly assume that only the first param matters... APIResultWrapper retVal = new APIResultWrapper<T>(result_type, target_class); postJsonObjectToUrl(params[0].getFullUrl(), params[0].getPostObj(), retVal); ArrayList<TrafficStat> objArr = new ArrayList<>(); try { if (retVal.getHttpStatus() != 200) { Log.e(TAG, "API Returned non-200, throwing error!"); Log.e(TAG, retVal.getParsedResponse().toString()); // Bit of a hack to work around the not-super-great error message the server hands back. :-) if (retVal.getHttpStatus() == 400) { retVal.addException(new APIException( "Please pick two points along the same colored section of highway.", retVal)); } try { // Since errors are still JSON we're going to parse it and get the message Object json = new JSONTokener(retVal.getParsedResponse().toString()).nextValue(); if (json instanceof JSONObject && ((JSONObject) json).has("error")) { retVal.addException(new APIException( ((JSONObject) json).getJSONObject("error").getString("message"), retVal)); } else { retVal.addException( new APIException("Server returned a 404 error when asked for statistics.", retVal)); } // Since we've got an exception object now, we need to parse it as an object...j } catch (JSONException e) { retVal.addException( new APIException("Server returned a 404 error when asked for statistics.", retVal)); } } else { // HTTP status was indeed 200! JSONObject parsedRawRes = retVal.getParsedResponse(); JSONArray jResult = parsedRawRes.getJSONArray("results"); Log.i(TAG, "Got results array: " + jResult); // Now loop through all the results and make the list if (jResult == null) { // No items were found? Sounds suspicious, but I guess we're done. Log.i("RESULT", "Apparently nothing was in the results array..."); } else { try { for (int i = 0; i < jResult.length(); i++) { //Create a JSONObject and use it to construct a TravelingInfo to add to the list JSONObject jsonObject = (JSONObject) jResult.get(i); objArr.add(new TrafficStat(jsonObject)); } } catch (JSONException e) { // TODO: Should we bubble this up or fail out if this happens? Log.e(TAG, "Ignored a specific result due to JSON Exception!"); } } } } catch (JSONException je) { // Going to log a message, but not abort the app... We'll just pretend there were no results. // This should never happen, as the parser should ensure that the results field exists Log.e(TAG, "Could not parse result out of JSON array"); } retVal.setListResponse(objArr); return retVal; } @Override protected void onPostExecute(APIResultWrapper result) { delegate.onApiResult(result); } public JSONObject postJsonObjectToUrl(String url, JSONObject jsonObject, APIResultWrapper retVal) { InputStream inputStream = null; String result = ""; try { // 1. create HttpClient HttpClient httpclient = new DefaultHttpClient(); // 2. make POST request to the given URL //http://capstoneaa.cs.pdx.edu/api/trafficstats HttpPost httpPost = new HttpPost(url); // 4. convert JSONObject to JSON to String String json = jsonObject.toString(); // 5. set json to StringEntity StringEntity se = new StringEntity(json); se.setContentType("application/json;charset=UTF-8"); se.setContentEncoding(new BasicHeader(HTTP.CONTENT_TYPE, "application/json;charset=UTF-8")); // 6. set httpPost Entity httpPost.setEntity(se); // 7. Set some headers to inform server about the type of the content // httpPost.setHeader("Accept", "application/json"); // httpPost.setHeader("Content-type", "application/json"); // 8. Execute POST request to the given URL HttpResponse httpResponse = httpclient.execute(httpPost); // Make sure we've got a good response from the API. int status = httpResponse.getStatusLine().getStatusCode(); retVal.setHttpStatus(status); result = EntityUtils.toString(httpResponse.getEntity()); //Log.i("RAW HTTP RESULT", result); retVal.setRawResponse(result); } catch (Exception e) { Log.e("InputStream", e.getLocalizedMessage()); } try { Object json = new JSONTokener(result).nextValue(); if (json instanceof JSONObject) { retVal.setParsedResponse((JSONObject) json); return (JSONObject) json; } } catch (JSONException e) { e.printStackTrace(); } // If we got this far, we got something very wrong... Log.e(TAG, "Didn't get a valid JSON response!"); return null; } private String convertInputStreamToString(InputStream inputStream) throws IOException { BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream)); String line = ""; String result = ""; while ((line = bufferedReader.readLine()) != null) result += line; inputStream.close(); return result; } }