Package nl.bebr.mapviewer.data.util

Class ConnectionChecker

java.lang.Object

nl.bebr.mapviewer.data.util.ConnectionChecker

public class ConnectionChecker
extends Object

Checks connection availability.

It uses to identify if machine is connected to internet, and
{@link java.net.Socket} to check, if address www.openstreetmap.org is accessible.

Check is running periodically in a {@link java.util.Timer} with period 5000 ms.

When status changes (from online to offline and vice versa) {@link java.beans.PropertyChangeListener} is fired.

Author:

Frantisek Post

Method Summary

Modifier and Type	Method	Description
void	addPropertyChangeListener(PropertyChangeListener listener)	Add property change listener
long	getCheckPeriod()	Return time in milliseconds between two checks
String	getHostName()	Return hostname, that is used to checked online status
static ConnectionChecker	getInstance()	Returns singleton instance
int	getPortNumber()	Return checked port number
boolean	isOnline()	Returns online status
boolean	isStarted()	Returns checker state
void	removePropertyChangeListener(PropertyChangeListener listener)	Remove property change listener
void	restart()	Restart checker to apply new settings.
void	setCheckPeriod(long checkPeriod)	Set time in milliseconds between two checks
void	setHostName(String hostName)	Set hostname to check online status
void	setPortNumber(int portNumber)	Set port number
void	start()	Starting checker.
void	stop()	Stopping checker

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

getInstance

public static ConnectionChecker getInstance()

Returns singleton instance

Returns:

isStarted

public boolean isStarted()

Returns checker state

Checker is started automatically when util module is loaded

Returns:

checker state

start

public void start()

Starting checker.

Checking timer starts immediately, with default period 2000 ms.

stop

public void stop()

Stopping checker

isOnline

public boolean isOnline()

Returns online status

Boolean type is used to be able to return answer "I don't know" in case the checker is not running

First testing if there is a connection. This should be quite fast. If connection is available, then return result of test in timer.

NOTE: Displable fast check since this could be blocking in case of slow dns server method just returns online state now.

Returns:

online status

addPropertyChangeListener

public void addPropertyChangeListener(PropertyChangeListener listener)

Add property change listener

Listener is fired with property name status in case status changes (online->offline, offline->online)

Parameters:

listener -

removePropertyChangeListener

public void removePropertyChangeListener(PropertyChangeListener listener)

Remove property change listener

Parameters:

listener -

getCheckPeriod

public long getCheckPeriod()

Return time in milliseconds between two checks

Returns:

setCheckPeriod

public void setCheckPeriod(long checkPeriod)

Set time in milliseconds between two checks

To apply new settings call restart()

Parameters:

checkPeriod -

getHostName

public String getHostName()

Return hostname, that is used to checked online status

Returns:

setHostName

public void setHostName(String hostName)

Set hostname to check online status

To apply new settings call restart()

Parameters:

hostName -

getPortNumber

public int getPortNumber()

Return checked port number

Returns:

setPortNumber

public void setPortNumber(int portNumber)

Set port number

To apply new settings call restart()

Parameters:

portNumber -

restart

public void restart()

Restart checker to apply new settings.

Actually calling stop() and start()