Generic Connection Framework
If you develop applications for
BlackBerry® device
users who are running
BlackBerry®
Device Software 4.7 or earlier, you need to use the GCF to open a network
connection. However, any code that you write that uses the GCF also runs on
later versions of
BlackBerry®
Device Software. The GCF is implemented in the
javax.microedition.io.Connector class. You can call
Connector.open() to create any type of supported
connection. The
open() method accepts a connection string that specifies
the type of connection to make, the end point, and optional configuration
details for the connection.
The connection string that is used by the GCF comprises three parts:
<scheme> :
<hierarchical location information> ;
<additional information>
The
<scheme> indicates the protocol to use to
establish the connection. The
<hierarchical location information> describes
the end point for the connection. Finally, the
<additional information> controls the transport
that is used, and provides authentication details for a proxy server if they
are required. For more information about transport options, see "Network
transport options".
For example, in the following code sample, the connection string
specifies the HTTP protocol and uses a host name to indicate the connection end
point. The
interface=wifi parameter is included to specify that the
Wi-Fi® radio should be used
to establish the connection.
HTTPConnection c = (HTTPConnection)Connector.open("http://example.com;interface=wifi");
Open a network connection using the GCF
The following task
shows you how to open an HTTP connection using the
BlackBerry® Mobile Data System transport. You can use a similar process to open a connection
using other protocols and transports.
CAUTION:
The
Connector.open() method is not thread-safe. Ensure
that you invoke
open() on a thread that is separate from the main
event thread.
Before you begin: Make sure that the
transport that you want to use is available and has coverage.
-
Import the required classes and interfaces.
import net.rim.device.api.ui.UiApplication;
import java.io.IOException;
import javax.microedition.io.*;
-
Create a new thread to open the connection.
Thread t = new Thread(new Runnable()
{
public void run()
{
-
Create a local variable for your
Connection object.
Connection conn = null;
-
Invoke
open(). Specify the connection string.
try
{
conn = Connector.open("http://www.blackberry.com;deviceside=false");
} catch (IOException e)
{
// Process your error condition
}
-
If the connection attempt was successful,
open() returns a
Connection object that you can use. Pass the
connection object to another method (displayContent()) that is
responsible for displaying the content.
if (conn != null)
{
displayContent(conn);
}
}
});
-
Start your thread.
t.start();
-
Implement
displayContent(). In this case, push a screen that
uses a
Connection parameter to retrieve and display the
content, after the connection retrieval thread completes.
private void displayContent(final Connection conn)
{
UiApplication.getUiApplication().invokeLater(new Runnable()
{
public void run() {
UiApplication.getUiApplication().pushScreen(new HTTPOutputScreen(conn));
}
});
}
After you finish:
For more information about using a connection, and implementing the
HTTPOutputScreen class, see "Send and receive data using
a network connection".
For a complete code sample, see "Code sample:
Retrieving a web page using the GCF".
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