Android Http Connection and SAX Parsing
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The document discusses Android networking and XML parsing using SAX. It describes how to make HTTP requests using URLConnection in Android, including opening a connection, preparing and sending requests, reading responses, and disconnecting. It also covers performing network requests asynchronously using AsyncTask to avoid blocking the UI thread. Finally, it provides an overview of XML parsing with SAX in Android.
Android Http Connection and SAX Parsing
- 1. Android Networking and XML Parsing (SAX) Jussi Pohjolainen
- 2. URLConnec@on 1. Obtain a new HttpURLConnection by calling URL.openConnection() and cas@ng the result to HGpURLConnec@on. 2. Prepare the request. (URI) 3. Op@onally upload a request body 4. Read the response. Response headers typically include metadata such as the response body's content type and length, modified dates and session cookies. The response body may be read from the stream returned by getInputStream(). 5. Disconnect. Once the response body has been read, the HttpURLConnection should be closed by calling disconnect(). Disconnec@ng frees all resources held by a connec@on.
- 3. Fetching URL URL url = new URL("http://www.somesite.fi"); HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection(); InputStream in = new BufferedInputStream(urlConnection.getInputStream()); String all = ""; int character; while((character = stream.read()) != -1) { all += (char) character; } urlConnection.disconnect();
- 4. Asynchronous HGp • It’s wise to fetch data in separate thread • Standard Java threading model can be used, but touching the UI thread is forbidden in Android • To update UI from background task, you need Android specific classes like Handler. • AsyncTask is a class that wraps threading and handling UI thread in the same class. (Hold’s Handler)
- 5. AsyncTask
- 6. AsyncTask
- 7. Generic Types • The three types used by an asynchronous task are the following: 1. Params, the type of the parameters sent to the task upon execu@on. 2. Progress, the type of the progress units published during the background computa@on. 3. Result, the type of the result of the background computa@on. private class MyTask extends AsyncTask<Void, Void, Void> { ... }
- 10. SAX • Standard Java SAX parsing or android api wrappers