selectgpsscreen.java

j2me的1套UI框架,可以帮助开发者迅速的开发j2me应用程序.

package org.j4me.examples.bluetoothgps;

import org.j4me.bluetoothgps.*;
import org.j4me.ui.*;
import org.j4me.ui.components.*;

/**
 * The "Select GPS Device" screen.  When the GPS is an external Bluetooth
 * device, and more than one are available within the area of the user,
 * this screen will be shown to let them select which device is theirs.
 */
public class SelectGPSScreen
	extends Dialog
{
	/**
	 * The location information for this application.
	 */
	private final LocationModel model;
	
	/**
	 * The screen to return to if the user cancels this one.
	 */
	private final DeviceScreen previous;
	
	/**
	 * Constructs the "Select GPS Device" screen.
	 * 
	 * @param model is the application's location data.
	 * @param previous is the screen to return to if this one is canceled.
	 */
	public SelectGPSScreen (LocationModel model, DeviceScreen previous)
	{
		setTitle( "Select GPS Device" );

		this.model = model;
		this.previous = previous;
	}
	
	/**
	 * Called by the Bluetooth device discovery process once completed
	 * to set the list of nearby devices.  These will be displayed to
	 * the user to select from.
	 * 
	 * @param devices are the available devices as returned from the
	 *  <c>LocationProvider.discoverBluetoothDevices</c> method.  This may
	 *  not be <c>null</c>.
	 * @see org.j4me.bluetoothgps.LocationProvider#discoverBluetoothDevices()
	 */
	public void setAvailableDevices (String[][] devices)
	{
		// Add a menu option for each Bluetooth device.
		deleteAll();
		
		for ( int i = 0; i < devices.length; i++ )
		{
			String[] device = devices[i];
			String name = device[0];
			String address = device[1];
			
			GPSDeviceOption option = new GPSDeviceOption( name, address );
			append( new MenuOption(option) );
		}
		
		// Add a final option to "Try Again".
		append( new MenuOption(new MenuItem()
			{
				public String getText ()
				{
					return "Try Again";
				}

				public void onSelection ()
				{
					FindingGPSDevicesAlert alert = new FindingGPSDevicesAlert( model, previous );
					alert.show();
				}
			} ));
	}
	
	/**
	 * The left menu button takes the user back to the previous screen.
	 * If there is no previous screen it has no effect.
	 * 
	 * @see DeviceScreen#declineNotify()
	 */	
	protected void declineNotify ()
	{
		// Go back to the previous screen.
		if ( previous != null )
		{
			previous.show();
		}

		// Continue processing the event.
		super.declineNotify();
	}

	/**
	 * The right menu button selects the highlighted menu item.
	 */	
	protected void acceptNotify ()
	{
		// Go to the highlighted screen.
		int highlighted = getSelected();
		Component component = get( highlighted );

		if ( component instanceof MenuOption )
		{
			MenuOption option = (MenuOption)component;
			option.select();
		}

		// Continue processing the event.
		super.acceptNotify();
	}
	
	/**
	 * A menu option for selecting a GPS device.
	 */
	private final class GPSDeviceOption
		implements MenuItem
	{
		/**
		 * The user friendly name of the GPS device.
		 */
		private final String name;
		
		/**
		 * The Bluetooth URL for the device.
		 */
		private final String address;
		
		/**
		 * Constructs a menu option for choosing a Bluetooth device.
		 * 
		 * @param name is the name of the Bluetooth device.
		 * @param address is the Bluetooth URL for the device. 
		 */
		public GPSDeviceOption (String name, String address)
		{
			this.name = name;
			this.address = address;
		}
		
		/**
		 * @return The name of the Bluetooth GPS device.
		 */
		public String getText ()
		{
			return name;
		}
	
		/**
		 * Called if the user selects this Bluetooth device.  It
		 * records it on the model and goes on to the next screen.
		 */
		public void onSelection ()
		{
			// Record the selected device.
			model.setBluetoothGPS( name, address );
			
			Criteria criteria = model.getCriteria();
			criteria.setAllowLocalLBS( false );
			criteria.setRemoteDeviceAddress( address );
			model.setCriteria( criteria );

			// Connect to the GPS.
			InitializingGPSAlert alert = new InitializingGPSAlert( model, SelectGPSScreen.this );
			alert.show();
		}
	}
}