Opening a network connection using the Network API
After you decide which network transports to use, you can open a
connection and use it to send and receive data. The
ConnectionFactory object is responsible for opening
connections. In addition to your preferred transports, you can use the
ConnectionFactory to configure connection options such
as:
- Maximum number of connection
attempts.
- Maximum time to spend making
connection attempts.
- Delay between connection
attempts.
- Whether or not encryption is
required between the connection end points.
When you are ready to open a connection, you should invoke one of the
ConnectionFactory.getConnection() methods. Be sure that
you call
getConnection() on a thread that is separate from the
main event thread. For more information about creating a thread, see the
Thread class in the API reference for the
BlackBerry® Java® SDK.
When you open a connection successfully, the
ConnectionFactory returns a
ConnectionDescriptor object. The
ConnectionDescriptor contains a
Connection object, and information about the transport
that was used to open the connection.
For more information, see "Open a network connection using the Network
API" and "Send and receive data using a network connection".
Open a network connection using the Network API
CAUTION:
The
ConnectionFactory.getConnection() method blocks thread
execution. You should create a separate thread to call
getConnection().
-
Import the required classes and interfaces.
import net.rim.device.api.io.transport.*;
import net.rim.device.api.io.transport.options.*;
import net.rim.device.api.io.transport.TransportInfo;
import net.rim.device.api.ui.UiApplication;
-
Create an ordered list of preferred transports.
int[] intTransports =
{ TransportInfo.TRANSPORT_TCP_WIFI,
TransportInfo.TRANSPORT_WAP2,
TransportInfo.TRANSPORT_TCP_CELLULAR
}
-
Configure the options for the TCP Cellular transport, if
applicable.
TcpCellularOptions tcpOptions = new TcpCellularOptions();
if(!TcpCellularOptions.isDefaultAPNSet())
{
tcpOptions.setApn("My APN");
tcpOptions.setTunnelAuthUsername("user");
tcpOptions.setTunnelAuthPassword("password");
}
-
Create a
ConnectionFactory object.
ConnectionFactory factory = new ConnectionFactory();
-
Set any other
ConnectionFactory options that are applicable to
your application. In this case, TCP Cellular is one of the preferred
transports, so set the TCP Cellular transport options.
factory.setTransportTypeOptions(TransportInfo.TRANSPORT_TCP_CELLULAR, tcpOptions);
factory.setAttemptsLimit(5);
-
Create a thread to retrieve the connection. If the connection was
successful, then
ConnectionFactory returns a
ConnectionDescriptor object that you can use. In
this step, pass the
ConnectionDescriptor object to another method
(displayContent()) that is responsible for displaying the
content.
Thread t = new Thread(new Runnable()
{
public void run()
{
ConnectionDescriptor cd = _factory.getConnection
("http://www.blackberry.com");
if(cd != null)
{
Connection c = cd.getConnection();
displayContent(c);
}
}
});
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 Network API".
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