Connecting to Web Services on Android - Presentation Transcript

Connecting to Web Services on Android - Presentation Transcript 1. Connecting to Web Services Sean Sullivan Android Dev Camp Amsterdam 8 January 2009 2. + 3. • HTTP • XML • JSON • OAuth 4. HTTP request XML response 5. http://code.google.com/p/jfireeagle 6. jfireeagle uses: • HttpClient API • XStream • OAuth Java library 7. “An open protocol to allow secure API authorization in a simple and standard method from desktop and web applications” 8. • use OAuth to access protected data • your application needs to obtain an access token from the service provider • service provider will issue access token after the user grants permission 9. + http://code.google.com/p/oauth 10. + jfireeagle http://code.google.com/p/jfireeagle/wiki/Android jpoco http://code.google.com/p/jpoco/wiki/Android 11. + HTTP Option 1 • java.net.URL • java.net.HttpURLConnection Option 2 • HttpClient 4.0 API 12. HttpClient 4.0 API • org.apache.http.client.HttpClient • org.apache.http.impl.client.DefaultHttpClient 13. HttpClient 4.0 API • org.apache.http.client.methods.HttpGet • org.apache.http.client.methods.HttpPost • org.apache.http.client.methods.HttpPut • org.apache.http.client.methods.HttpDelete 14. HttpClient 4.0 API • org.apache.http.HttpResponse • org.apache.http.StatusLine • org.apache.http.HttpEntity • org.apache.http.utils.EntityUtils 15. HttpClient programming • HTTP response status code • I/O exceptions • timeouts • gzip? 16. HttpClient programming synchronous invocation public HttpResponse execute(HttpUriRequest request) asynchronous invocation public HttpResponse execute(HttpUriRequest request, ResponseHandler handler) 17. Android UI thread • user clicks on button • onClick listener • Don’t block the UI thread! • Tip: use java.lang.Runnable 18. Response formats • XML • JSON • RSS, Atom • other 19. XML processing • org.w3c.dom package (DOM) • org.xml.sax package (SAX) • org.xmlpull package (XPP3) • XStream • JDOM • Apache XmlBeans * * does not work on Android 1.0 20. JSON processing • org.json package • Google GSON library * • XStream + Jettison * • json-lib * * does not work on Android 1.0 21. Client libraries • code.google.com/p/jfireeagle • code.google.com/p/jpoco • code.google.com/p/meetup-java-client • code.google.com/p/upcoming-java-client • code.google.com/p/gdata-java-client • flickrj.sourceforge.net 22. Conclusion • HttpClient API • use XStream for XML processing • use org.json package for JSON processing • OAuth has a learning curve • OAuth affects user experience 23. Thank you 24. Resources • http://code.google.com/android/documentation.html • http://hc.apache.org/httpcomponents-client • http://code.google.com/p/oauth • http://xstream.codehaus.org