Download XML from a Web Server: Android Programming

• Report rights infringement
• published: 12 Mar 2013
• views: 23312

Tutorial showing how to download XML data from a sample Google AppEngine web server (http://demoprojectserver1234.appspot.com/) in an Android project. Full Android code below. // imports omitted due to YouTube space restriction! // Some code based on content in Android Application Development in 24 hours by Darcey and Conder (2nd ed). /** * Demonstrate querying a basic application server for information. * */ public class MainActivity extends Activity { private static final String TAG = "ProjectServerDemo"; public static final String APP_ID = "3fa19507-c746-4dfa-8ded-ec60ef4d30d9"; public static final String SERVER_URL = "http://demoprojectserver1234.appspot.com/"; public static final String QUERY_FILE = "xmlquery.cgi"; public static final String QUERY_OPTIONS = "?appid=" + APP_ID; public static final String QUERY_URL = SERVER_URL + QUERY_FILE + QUERY_OPTIONS; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); } public void onClick_ClearDisplay(View v) { TextView textView = (TextView) findViewById(R.id.displayData); textView.setText(""); } public void onClick_QueryServer(View v) { Log.i(TAG, "Query server..."); AsyncDownloader downloader = new AsyncDownloader(); downloader.execute(); } private void handleNewRecord(String itemId, String data) { TextView textView = (TextView) findViewById(R.id.displayData); String message = textView.getText().toString() + "\n" + itemId + ": " + data; textView.setText(message); } // Inner class for doing background download. // REVISIT:- Change the [[ to a less than; ]] to a greater than. // (YouTube won't let you use those characters...) private class AsyncDownloader extends AsyncTask[[Object, String, Integer]] { @Override protected Integer doInBackground(Object... arg0) { XmlPullParser receivedData = tryDownloadingXmlData(); int recordsFound = tryParsingXmlData(receivedData); return recordsFound; } private XmlPullParser tryDownloadingXmlData() { try { Log.i(TAG, "Now downloading..."); URL xmlUrl = new URL(QUERY_URL); XmlPullParser receivedData = XmlPullParserFactory.newInstance().newPullParser(); receivedData.setInput(xmlUrl.openStream(), null); return receivedData; } catch (XmlPullParserException e) { Log.e(TAG, "XmlPullParserExecption", e); } catch (IOException e) { Log.e(TAG, "XmlPullParserExecption", e); } return null; } private int tryParsingXmlData(XmlPullParser receivedData) { if (receivedData != null) { try { return processReceivedData(receivedData); } catch (XmlPullParserException e) { Log.e(TAG, "Pull Parser failure", e); } catch (IOException e) { Log.e(TAG, "IO Exception parsing XML", e); } } return 0; } private int processReceivedData(XmlPullParser xmlData) throws XmlPullParserException, IOException { int recordsFound = 0; // Find values in the XML records String appId = ""; // Attributes String itemId = ""; String timeStamp = ""; String data = ""; // Text int eventType = -1; while (eventType != XmlResourceParser.END_DOCUMENT) { String tagName = xmlData.getName(); switch (eventType) { case XmlResourceParser.START_TAG: // Start of a record, so pull values encoded as attributes. if (tagName.equals("record")) { appId = xmlData.getAttributeValue(null, "appid"); itemId = xmlData.getAttributeValue(null, "itemid"); timeStamp = xmlData.getAttributeValue(null, "timestamp"); data = ""; } break; // Grab data text (very simple processing) // NOTE: This could be full XML data to process. case XmlResourceParser.TEXT: data += xmlData.getText(); break; case XmlPullParser.END_TAG: if (tagName.equals("record")) { recordsFound++; publishProgress(appId, itemId, data, timeStamp); } break; } eventType = xmlData.next(); } // Handle no data available: Publish an empty event. if (recordsFound == 0) { publishProgress(); } Log.i(TAG, "Finished processing "+recordsFound+" records."); return recordsFound; } @Override protected void onProgressUpdate(String... values) { if (values.length == 0) { Log.i(TAG, "No data downloaded"); } if (values.length == 4) { String appId = values[0]; String itemId = values[1]; String data = values[2]; String timeStamp = values[3]; // Log it Log.i(TAG, "AppID: " + appId + ", Timestamp: " + timeStamp); Log.i(TAG, " ItemID: " + itemId + ", Data: " + data); // Pass it to the application handleNewRecord(itemId, data); } super.onProgressUpdate(values); } } }