Wireless Java

Invoking Remote Applications from MIDlets

Now let’s look at some examples of fetching HTTP pages and invoking CGI scripts and servlets from MIDlets using the connection framework.

Fetching a Page

Example 7-1 shows how to read the contents of a file referenced by a URL, using a StreamConnection . An HttpConnection can also be used, but since no HTTP-specific behavior is needed here, the StreamConnection is used. The application is very simple. The Connector.open( ) method opens a connection to the URL and returns a StreamConnection object. Then an InputStream is opened through which to read the contents of the file, one character at a time, until the end of the file (signaled by a character value of -1) is reached. In the event that an exception is thrown, both the stream and connection are closed.

Example 7-1. Fetching a page referenced by a URL

import java.io.*; import javax.microedition.io.*; import javax.microedition.lcdui.*; import javax.microedition.midlet.*; public class FetchPageMidlet extends MIDlet { private Display display; String url = "http://www.javacourses.com/hello.txt"; public FetchPageMidlet( ) { display = Display.getDisplay(this); } /** * This will be invoked when we start the MIDlet */ public void startApp( ) { try { getViaStreamConnection(url); } catch (IOException e) { //Handle Exceptions any other way you like. System.out.println("IOException " + e); e.printStackTrace( ); } } /** * Pause, discontinue .... */ public void pauseApp( ) { } /** * Destroy must cleanup ...