1. Mobile Programming Lecture 14 Communicating via the Internet

2. Agenda A look at HTML HttpUrlConnection HttpGet A more in-depth look at XML Introducing JSON Introducing Web APIs ProgrammableWeb.com

3. A look at HTML Go to http://www.imdb.com and search for your favorite movie Right click on the page and view the source Not surprisingly, you will find that the source behind the page is not easy to read

4. A look at HTML You can load HTML into a WebView Try this WebView wv = (WebView) findViewById(R.id.webView); wv.loadData(" Hi Mom! Dad," + " sup? ", "text/html", "UTF-8");

5. A look at HTML HTTP defines 9 methods/verbs indicating the desired action to be performed on a URL For now, we will only look at 2 of the verbs o GET o POST

6. A look at HTML HTTP GET o Requests a representation of the specified resource. Requests using GET should only retrieve data and should have no other effectretrieve data HTTP POST o Submits data to be processed (e.g., from an HTML form) to the identified resource. The data is included in the body of the request.HTML form

7. A look at HTML Get is like a query. You can usually modify the arguments to the query directly Not the same with POST!

8. A look at HTML What if you want to read this data (the HTML source) in Android?

9. HttpUrlConnection used to send and receive data over the web data may be of any type and length

10. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); }

11. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); } We will use this WebView to display a page

12. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); } We need to run network routines on a separate thread, otherwise we will get Exceptions

13. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); } To run a block of code on a separate thread (i.e., not on the UI aka main thread)

14. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); } Create an instance of Thread

15. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); } Pass an anonymous inner Runnable class as the argument to the Thread constructor

16. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); } Override the run() method of Runnable

17. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); } Add your code block to the run() method

18. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); } Call start() on the Thread

19. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); } URL object identifies the location of an Internet resource

20. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); } HttpURLConnection used to (send and) receive data over the Internet

21. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); } Get an instance of it by calling openConnection() on the URL

22. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); } Get an InputStream for reading in the data

23. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); } A one-liner that I stole from here for reading in all of the data using the InputStream here

24. HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); } Release the resources held by the connection

25. data should now contain the HTML returned by the URL. We load the data into the WebView HttpUrlConnection @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); wv = (WebView) findViewById(R.id.webView); new Thread(new Runnable() { @Override public void run() { URL url = new URL("http://mobile.cs.fsu.edu/"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); data = new java.util.Scanner(in).useDelimiter("\\A").next(); urlConnection.disconnect(); wv.loadData(data, "text/html", "UTF-8"); } }).start(); }

26. A look at HTML HTML tells the browser how the server wants to display information to the user How would the server send this information to your device, efficiently?

27. HttpUrlConnection See HttpUrlConnectionExample.tar

28. HttpUrlConnection What happens if we try to open a connection to an invalid URL? URL url = new URL("http://mobiles.cs.fsu.edu/"); with an extra "s" after mobile, instead of URL url = new URL("http://mobile.cs.fsu.edu/");

29. HttpUrlConnection We need to check the HTTP response code for errors first, then act accordingly

30. HttpGet HttpClient client = new DefaultHttpClient(); HttpGet request = new HttpGet(); request.setURI(new URI("http://mobile.cs.fsu.edu/androids")); HttpResponse response = client.execute(request); final int statusCode = response.getStatusLine().getStatusCode(); if(statusCode == 200) { in = new BufferedReader(new InputStreamReader(response.getEntity().getContent())); StringBuffer sb = new StringBuffer(""); String line = ""; String NL = System.getProperty("line.separator"); while ((line = in.readLine()) != null) sb.append(line + NL); in.close(); browser.loadData(sb.toString(), "text/html", "UTF-8"); }

31. HttpGet HttpClient client = new DefaultHttpClient(); HttpGet request = new HttpGet(); request.setURI(new URI("http://mobile.cs.fsu.edu/androids")); HttpResponse response = client.execute(request); final int statusCode = response.getStatusLine().getStatusCode(); if(statusCode == 200) { in = new BufferedReader(new InputStreamReader(response.getEntity().getContent())); StringBuffer sb = new StringBuffer(""); String line = ""; String NL = System.getProperty("line.separator"); while ((line = in.readLine()) != null) sb.append(line + NL); in.close(); browser.loadData(sb.toString(), "text/html", "UTF-8"); } This takes care of a bunch of mumbo jumbo that you don't want to deal with

32. HttpGet HttpClient client = new DefaultHttpClient(); HttpGet request = new HttpGet(); request.setURI(new URI("http://mobile.cs.fsu.edu/androids")); HttpResponse response = client.execute(request); final int statusCode = response.getStatusLine().getStatusCode(); if(statusCode == 200) { in = new BufferedReader(new InputStreamReader(response.getEntity().getContent())); StringBuffer sb = new StringBuffer(""); String line = ""; String NL = System.getProperty("line.separator"); while ((line = in.readLine()) != null) sb.append(line + NL); in.close(); browser.loadData(sb.toString(), "text/html", "UTF-8"); } Use HttpGet to retrieve whatever information is identified by the request-URI

33. HttpGet HttpClient client = new DefaultHttpClient(); HttpGet request = new HttpGet(); request.setURI(new URI("http://mobile.cs.fsu.edu/androids")); HttpResponse response = client.execute(request); final int statusCode = response.getStatusLine().getStatusCode(); if(statusCode == 200) { in = new BufferedReader(new InputStreamReader(response.getEntity().getContent())); StringBuffer sb = new StringBuffer(""); String line = ""; String NL = System.getProperty("line.separator"); while ((line = in.readLine()) != null) sb.append(line + NL); in.close(); browser.loadData(sb.toString(), "text/html", "UTF-8"); } set the URI!

34. HttpGet HttpClient client = new DefaultHttpClient(); HttpGet request = new HttpGet(); request.setURI(new URI("http://mobile.cs.fsu.edu/androids")); HttpResponse response = client.execute(request); final int statusCode = response.getStatusLine().getStatusCode(); if(statusCode == 200) { in = new BufferedReader(new InputStreamReader(response.getEntity().getContent())); StringBuffer sb = new StringBuffer(""); String line = ""; String NL = System.getProperty("line.separator"); while ((line = in.readLine()) != null) sb.append(line + NL); in.close(); browser.loadData(sb.toString(), "text/html", "UTF-8"); } Check this link out to learn more about status codes.this link 200 means OK!

35. HttpGet HttpClient client = new DefaultHttpClient(); HttpGet request = new HttpGet(); request.setURI(new URI("http://mobile.cs.fsu.edu/androids")); HttpResponse response = client.execute(request); final int statusCode = response.getStatusLine().getStatusCode(); if(statusCode == 200) { in = new BufferedReader(new InputStreamReader(response.getEntity().getContent())); StringBuffer sb = new StringBuffer(""); String line = ""; String NL = System.getProperty("line.separator"); while ((line = in.readLine()) != null) sb.append(line + NL); in.close(); browser.loadData(sb.toString(), "text/html", "UTF-8"); } If the status is OK, then write the rest of the code that will handle a successful GET

36. HttpGet HttpClient client = new DefaultHttpClient(); HttpGet request = new HttpGet(); request.setURI(new URI("http://mobile.cs.fsu.edu/androids")); HttpResponse response = client.execute(request); final int statusCode = response.getStatusLine().getStatusCode(); if(statusCode == 200) { in = new BufferedReader(new InputStreamReader(response.getEntity().getContent())); StringBuffer sb = new StringBuffer(""); String line = ""; String NL = System.getProperty("line.separator"); while ((line = in.readLine()) != null) sb.append(line + NL); in.close(); browser.loadData(sb.toString(), "text/html", "UTF-8"); } Then you may also wish to handle cases when the status is NOT OK.

37. HttpGet See HttpGetExample.tar

38. In-depth Look at XML XML doesn't replace HTML XML doesn't do anything o something is done with the XML You can invent your own tags with XML

39. In-depth Look at XML Simplifies data sharing Simplifies data transport You can invent your own tags with XML

40. In-depth Look at XML Tove Jani Reminder Don't forget me this weekend!

41. In-depth Look at XML Everyday Italian Giada De Laurentiis 2005 30.00 Harry Potter J K. Rowling 2005 29.99 Snow White Brothers Grimm 1812 39.95

42. In-depth Look at XML Everyday Italian Giada De Laurentiis 2005 30.00 Harry Potter J K. Rowling 2005 29.99 Snow White Brothers Grimm 1812 39.95 "bookstore" is the root element

43. In-depth Look at XML Everyday Italian Giada De Laurentiis 2005 30.00 Harry Potter J K. Rowling 2005 29.99 Snow White Brothers Grimm 1812 39.95 bookstore has 3 children

44. In-depth Look at XML Everyday Italian Giada De Laurentiis 2005 30.00 Harry Potter J K. Rowling 2005 29.99 Snow White Brothers Grimm 1812 39.95 each one is a "sibling" to the other (title, author, year, price)

45. In-depth Look at XML Everyday Italian Giada De Laurentiis 2005 30.00 Harry Potter J K. Rowling 2005 29.99 Snow White Brothers Grimm 1812 39.95 An element may have children (book element has 4 children in this case)

46. In-depth Look at XML Everyday Italian Giada De Laurentiis 2005 30.00 Harry Potter J K. Rowling 2005 29.99 Snow White Brothers Grimm 1812 39.95 and or attributes

47. In-depth Look at XML Everyday Italian Giada De Laurentiis 2005 30.00 Harry Potter J K. Rowling 2005 29.99 Snow White Brothers Grimm 1812 39.95 and/or data

48. In-depth Look at XML Everyday Italian Giada De Laurentiis 2005 30.00 Harry Potter J K. Rowling 2005 29.99 Snow White Brothers Grimm 1812 39.95 attribute values must always be within double quotes

49. In-depth Look at XML You can use an XML parser in Java to parse an XML file, in order to get the desired information

50. In-depth Look at XML How do we get the movie information from IMDB? We can only hope that someone has made the data available to us via XML

51. In-depth Look at XML Go to http://www.imdbapi.com and search for your favorite movie again Woops, the data is not represented as XML o append the string "&r=xml" to the end of the URL o or click here to be inceptedhere Take a look at the XML data o Can you interpret it? o Can a machine interpret it?

52. Parsing XML In Android, you may want to read this XML data, parse it, then display some parts of the data on an Android device

53. Parsing XML First, use HttpGet to execute a request to the same URL which returns data in XML format Then, if the status is OK, fetch the data and store it into a String (String raw for this example) Then...

54. Parsing XML DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); Document doc = builder.parse(new InputSource(new StringReader(raw))); NodeList movies = doc.getElementsByTagName("movie"); final Element movie = (Element) movies.item(0); final String moviePlot = "" + movie.getAttribute("plot"); mTextMoviePlot.post(new Runnable() { @Override public void run() { mTextMoviePlot.setText(moviePlot); } });

55. Parsing XML DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); Document doc = builder.parse(new InputSource(new StringReader(raw))); NodeList movies = doc.getElementsByTagName("movie"); final Element movie = (Element) movies.item(0); final String moviePlot = "" + movie.getAttribute("plot"); mTextMoviePlot.post(new Runnable() { @Override public void run() { mTextMoviePlot.setText(moviePlot); } }); There are several XML parsers available to you. Here we use the W3C DOM parser

56. Parsing XML DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); Document doc = builder.parse(new InputSource(new StringReader(raw))); NodeList movies = doc.getElementsByTagName("movie"); final Element movie = (Element) movies.item(0); final String moviePlot = "" + movie.getAttribute("plot"); mTextMoviePlot.post(new Runnable() { @Override public void run() { mTextMoviePlot.setText(moviePlot); } }); This Document represents the entire XML document

57. Parsing XML DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); Document doc = builder.parse(new InputSource(new StringReader(raw))); NodeList movies = doc.getElementsByTagName("movie"); final Element movie = (Element) movies.item(0); final String moviePlot = "" + movie.getAttribute("plot"); mTextMoviePlot.post(new Runnable() { @Override public void run() { mTextMoviePlot.setText(moviePlot); } }); Take a look at the XML file in the browser again. Here we get all of the elements having the tag "movie", in this case there's just one

58. Parsing XML DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); Document doc = builder.parse(new InputSource(new StringReader(raw))); NodeList movies = doc.getElementsByTagName("movie"); final Element movie = (Element) movies.item(0); final String moviePlot = "" + movie.getAttribute("plot"); mTextMoviePlot.post(new Runnable() { @Override public void run() { mTextMoviePlot.setText(moviePlot); } }); From the list of movies (although there's only one), here we get the first movie element

59. Parsing XML DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); Document doc = builder.parse(new InputSource(new StringReader(raw))); NodeList movies = doc.getElementsByTagName("movie"); final Element movie = (Element) movies.item(0); final String moviePlot = "" + movie.getAttribute("plot"); mTextMoviePlot.post(new Runnable() { @Override public void run() { mTextMoviePlot.setText(moviePlot); } }); As you can see, it would be easy to iterate through multiple movie elements using an index

60. Parsing XML DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); Document doc = builder.parse(new InputSource(new StringReader(raw))); NodeList movies = doc.getElementsByTagName("movie"); final Element movie = (Element) movies.item(0); final String moviePlot = "" + movie.getAttribute("plot"); mTextMoviePlot.post(new Runnable() { @Override public void run() { mTextMoviePlot.setText(moviePlot); } }); The movie element has a plot attribute, that's what we want to retrieve in this example

61. Parsing XML DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); Document doc = builder.parse(new InputSource(new StringReader(raw))); NodeList movies = doc.getElementsByTagName("movie"); final Element movie = (Element) movies.item(0); final String moviePlot = "" + movie.getAttribute("plot"); mTextMoviePlot.post(new Runnable() { @Override public void run() { mTextMoviePlot.setText(moviePlot); } }); Now we want to update the TextView, but we're not currently inside of the UI thread

62. Parsing XML DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); Document doc = builder.parse(new InputSource(new StringReader(raw))); NodeList movies = doc.getElementsByTagName("movie"); final Element movie = (Element) movies.item(0); final String moviePlot = "" + movie.getAttribute("plot"); mTextMoviePlot.post(new Runnable() { @Override public void run() { mTextMoviePlot.setText(moviePlot); } }); So we need to do fancy stuff.

63. Parsing XML DocumentBuilder builder = DocumentBuilderFactory.newInstance().newDocumentBuilder(); Document doc = builder.parse(new InputSource(new StringReader(raw))); NodeList movies = doc.getElementsByTagName("movie"); final Element movie = (Element) movies.item(0); final String moviePlot = "" + movie.getAttribute("plot"); mTextMoviePlot.post(new Runnable() { @Override public void run() { mTextMoviePlot.setText(moviePlot); } }); The post() method of the View class takes a runnable, and runs it on the UI thread

64. Parsing XML See HttpGetXmlExample.tar

65. XML Efficiency How can we represent this data more efficiently? Tove Jani Reminder Don't forget me this weekend!

66. XML Efficiency How can we represent this data more efficiently? Tove Jani Reminder Don't forget me this weekend! 133 characters { "to":"Tove", "from": "Jani", "heading":"Reminder", "body":"Don't forget me this weekend!" } 88 characters

67. XML Efficiency How can we represent this data more efficiently? Tove Jani Reminder Don't forget me this weekend! 133 characters This syntax called JSON { "to":"Tove", "from": "Jani", "heading":"Reminder", "body":"Don't forget me this weekend!" } 88 characters

68. JSON Values "title" : "IT Business Analyst Intern" "organization" : "Medtronic" "city" : "Brooklyn Park"

69. JSON Arrays "details" : [ "bla bla bla", "drank some soda", "hit manager in face with pie"]

70. JSON Objects { "title" : "IT Business Analyst Intern", "organization" : "Medtronic", "city" : "Brooklyn Park", "state" : "MN", "start_date" : "05/10", "end_date" : "07/10", "details" : [ "bla bla bla", "drank some soda", "hit manager in face with pie"] }

71. Parsing JSON JSONObject json = new JSONObject(raw); final String moviePlot = "" + json.getString("Plot"); mTextMoviePlot.post(new Runnable() { @Override public void run() { mTextMoviePlot.setText(moviePlot); } });

72. Parsing JSON JSONObject json = new JSONObject(raw); final String moviePlot = "" + json.getString("Plot"); mTextMoviePlot.post(new Runnable() { @Override public void run() { mTextMoviePlot.setText(moviePlot); } }); JSONObject is a set of name/value mappings, can represent a JSON document

73. Parsing JSON JSONObject json = new JSONObject(raw); final String moviePlot = "" + json.getString("Plot"); mTextMoviePlot.post(new Runnable() { @Override public void run() { mTextMoviePlot.setText(moviePlot); } }); Retrieve the plot of the movie

74. Parsing JSON Parsing JSON is not always this simple however, but it's usually straightforward once you understand JSON A JSONObject may consist of more JSONObjects, JSONArrays, Strings, Booleans, Integers, etc

75. Parsing JSON { "title" : "IT Business Analyst Intern", "organization" : "Medtronic", "city" : "Brooklyn Park", "state" : "MN", "start_date" : "05/10", "end_date" : "07/11", "details" : [ "bla bla bla", "drank some soda", "hit manager in face with pie"] }

76. Parsing JSON { "title" : "IT Business Analyst Intern", "organization" : "Medtronic", "city" : "Brooklyn Park", "state" : "MN", "start_date" : "05/10", "end_date" : "07/11", "details" : [ "bla bla bla", "drank some soda", "hit manager in face with pie"] } This is a JSONObject

77. Parsing JSON { "title" : "IT Business Analyst Intern", "organization" : "Medtronic", "city" : "Brooklyn Park", "state" : "MN", "start_date" : "05/10", "end_date" : "07/11", "details" : [ "bla bla bla", "drank some soda", "hit manager in face with pie"] } You can get title by calling getString("title") on the JSONObject

78. Parsing JSON { "title" : "IT Business Analyst Intern", "organization" : "Medtronic", "city" : "Brooklyn Park", "state" : "MN", "start_date" : "05/10", "end_date" : "07/11", "details" : [ "bla bla bla", "drank some soda", "hit manager in face with pie"] } You can get organization by calling getString("organization") on the JSONObject

79. Parsing JSON { "title" : "IT Business Analyst Intern", "organization" : "Medtronic", "city" : "Brooklyn Park", "state" : "MN", "start_date" : "05/10", "end_date" : "07/11", "details" : [ "bla bla bla", "drank some soda", "hit manager in face with pie"] } Etcetera, etcetera...

80. Parsing JSON { "title" : "IT Business Analyst Intern", "organization" : "Medtronic", "city" : "Brooklyn Park", "state" : "MN", "start_date" : "05/10", "end_date" : "07/11", "details" : [ "bla bla bla", "drank some soda", "hit manager in face with pie"] } This however, is not a String, but an array. Get this by calling getJSONArray() on the JSONObject

81. Parsing JSON { "title" : "IT Business Analyst Intern", "organization" : "Medtronic", "city" : "Brooklyn Park", "state" : "MN", "start_date" : "05/10", "end_date" : "07/11", "details" : [ "bla bla bla", "drank some soda", "hit manager in face with pie"] } After which you can use the getters on the JSONArray to get the desired data

82. Parsing JSON How would you represent this data using XML? { "title" : "IT Business Analyst Intern", "organization" : "Medtronic", "city" : "Brooklyn Park", "state" : "MN", "start_date" : "05/10", "end_date" : "07/11", "details" : [ "bla bla bla", "drank some soda", "hit manager in face with pie"] }

83. Parsing JSON See HttpGetJsonExample.tar

84. Introducing Web APIs In our IMDB example, we saw data that we wanted to use on another machine Luckily, someone created imdbapi.com, allowing us to read this data from a machine Data isn't always available however, the developer of the web site has to make the data available to other developers o Take VISA for example, they wouldn't just make your private data available! o Or ESPN, who only recently opened up an API for developers to use

85. Introducing Web APIs What is a Web API? According to Wikipedia... A Web API is a defined set of HTTP request messages along with a definition of the structure of response messages, typically expressed in JSON or XMLHTTPJSON

86. Introducing Web APIs You use a Web API because there's data somewhere that you want to use, and the best way for you to retrieve the data is via JSON or XML You don't want to see the data graphically, you just want to use it

87. Introducing Web APIs Some more examples of GET requests http://droidelicious.com/rest_example/api.php/api/users http://droidelicious.com/rest_example/api.php/api/users/3

88. Introducing Web APIs - Twitter Let's look at the Twitter public API, a more complicated example Look at this Twitter profile https://twitter.com/#!/Android Let's get the profile image from here https://twitter.com/statuses/user_timeline/Android.json https://twitter.com/statuses/user_timeline/Android.json

89. Introducing Web APIs - Twitter See JsonTwitterExample.tar

90. Introducing Web APIs Communication in this way involves a client (your device) and a server (twitter.com)

91. Introducing Web APIs Note: Sometimes you need an API key in order to use an API

92. References The Busy Coder's Guide to Android Development - Mark Murphy The Busy Coder's Guide to Android Development - Mark Murphy Android Developers The Mobile Lab at Florida State University