org.eclipse.paho.sample.utility

Class MQTTFrame

java.lang.Object

org.eclipse.paho.sample.utility.MQTTFrame

All Implemented Interfaces:

ActionListener, Runnable, EventListener, MqttCallback

public class MQTTFrame
extends Object
implements ActionListener, MqttCallback, Runnable

This class is the controlling class for the application. It contains the main method for launching the Swing GUI and itcontrols the MQTT connection.

Field Summary

Fields

Modifier and Type	Field and Description
protected static Dimension	DROP_DOWN_DIMENSION Constant controlling the display of JComboBoxes
protected static int	FRAME_HEIGHT
protected static int	FRAME_WIDTH
protected static Dimension	TEXT_FIELD_DIMENSION Constant controlling the display of JTextFields
protected static Insets	TEXT_MARGINS

Constructor Summary

Constructors

Constructor and Description
MQTTFrame() Constructor for MQTTFrame

Method Summary

Modifier and Type	Method and Description
void	actionPerformed(ActionEvent e) Implement the ActionListener interface and catch user interface events.
void	connect(String connStr, boolean usePersistence) A wrapper for the MQTT connect method.
void	connectionLost(Throwable cause) The method is part of the MqttSimpleCallback interface In the event of the MQTT connection being broken the LED is set to colour amber and made to flash.
String	constructPropertyValue(String prop) For a given property key construct a value to associate with the key The value can then be inserted in a properties object
void	deliveryComplete(IMqttDeliveryToken token) Called when delivery for a message has been completed, and all acknowledgments have been received.
void	disconnect() A wrapper for the MQTT disconnect method.
void	getProperties(Properties props, JComboBox comp, String key, String defValue) Add properties from a Properties object to a JComboBox.
protected void	init(Container contentPane) This method builds all the components to add to the content pane of the JFrame window.
static void	main(String[] args) The main method for launching the GUI.
void	messageArrived(String topic, MqttMessage message) The method is part of the MqttCallback interface Pass the message as is to the SubPanel object which will display it.
void	publish(String topic, byte[] message, int qos, boolean retained) A simple wrapper for the MQTT publish method.
void	run() Invoked by actionPerformed when connect is pressed.
void	setTitleText(String extraText) This method accepts a string on text and displays it in the window's title bar.
void	startTrace() This method calls the MQTT startTrace method to produce trace of the protocol flows
void	stopTrace() This method calls the MQTT stopTrace method to stop trace of the protocol flows
void	subscription(String topic, int qos, boolean sub) This method is called when either the subscribe or unsubscribe buttons are pressed.
boolean	updateComboBoxList(JComboBox list, String itemName) This method handles string items in JComboBox drop downs.
void	updatePublishTopicList(String topicName) If a new topic is typed into the subscribe topic box then the publish topic box needs to be updated.
void	updateSubscribeTopicList(String topicName) If a new topic is typed into the publish topic box then the subscribe topic box needs to be updated.
void	writeLog(String logdata) Write to the history dialog window
void	writeLogln(String logdata) Write to the history dialog window and append a newline character after the text

Methods inherited from class java.lang.Object

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

Field Detail

TEXT_FIELD_DIMENSION

protected static final Dimension TEXT_FIELD_DIMENSION

Constant controlling the display of JTextFields

DROP_DOWN_DIMENSION

protected static final Dimension DROP_DOWN_DIMENSION

Constant controlling the display of JComboBoxes

TEXT_MARGINS

protected static final Insets TEXT_MARGINS

FRAME_WIDTH

protected static final int FRAME_WIDTH

See Also:

Constant Field Values

FRAME_HEIGHT

protected static final int FRAME_HEIGHT

See Also:

Constant Field Values

Constructor Detail

MQTTFrame

public MQTTFrame()

Constructor for MQTTFrame

Method Detail

main

public static void main(String[] args)

The main method for launching the GUI. The main method takes no arguments.
This method attaches a WindowListener to the window to detect windowClosing events. When such an event is detected then various parameters are gathered from the GUI and written to a properties file before the application exits.

Parameters:

args - No arguments are required.

init

protected void init(Container contentPane)

This method builds all the components to add to the content pane of the JFrame window. It builds the connect panel itself and delegates building of the publish and subscribe panels to the PubPanel and SubPanel objects respectively. It also loads the properties file and gives the window a Windows look and feel.

Parameters:

contentPane - - The content pane of the JFrame window.

publish

public void publish(String topic,
                    byte[] message,
                    int qos,
                    boolean retained)
             throws Exception

A simple wrapper for the MQTT publish method. This method is invoked as a result of the publish button being pressed. If a problem is detected then an exception is thrown and an error message is displayed in the window title bar or in a separate dialog box.

Parameters:

topic - The topic on which the data will be published.

message - The data to be published

qos - The Quality of Service at which the publication should be delivered.

retained - Is this a retained publication or not?

Throws:

Exception

disconnect

public void disconnect()

A wrapper for the MQTT disconnect method. As well as disconnecting the protocol this method enables / disables buttons as appropriate when in disconnected state. It also sets the correct colour of the indicator LED.

connect

public void connect(String connStr,
                    boolean usePersistence)
             throws MqttException

A wrapper for the MQTT connect method. If the ip address, port number or persistence flag has changed since the last time then a new MqttClient object is required. If these values haven't changed then any previously created object can be used.

Check whether Last Will & Testament is required and call the appropriate connect method. The only persistence implementation supported at the moment is MqttFilePersistence.

Parameters:

ipAddr - The IP address or hostname to connect to.

port - The IP port number to connect to.

usePersistence - Is persistence required?

Throws:

MqttException

subscription

public void subscription(String topic,
                         int qos,
                         boolean sub)

This method is called when either the subscribe or unsubscribe buttons are pressed. It performs the MQTT subscribe or unsubscribe and writes an entry in the history log if the history window is open.
Any exceptions are caught and displayed in a dialog box.

Parameters:

topic - The topic to subscribe to

qos - The maximum Quality of Service at which to receive publications

sub - Is this a subscribe or unsubscribe operation? (true if subscribe).

run

public void run()

Invoked by actionPerformed when connect is pressed. This allows actionPerformed to return and paint the window. This thread then does the MQTT connect to the broker.
This method also ensures that the LED colour is set correctly and writes an entry to the history dialog if it is open.

Specified by:

run in interface Runnable

actionPerformed

public void actionPerformed(ActionEvent e)

Implement the ActionListener interface and catch user interface events. Button pressed events handled are as follows:

• Connect - Check the client is not already connected, set the LED colour to amber to indicate connect is in progress and start a thread to do the connect.
• Disconnect - Check the client is connected and then disconnect the MQTT protocol
• Otions - If the options dialog is opened then reset it's size and position to default values before making it visible

Specified by:

actionPerformed in interface ActionListener

Parameters:

e - The action event to process.

setTitleText

public void setTitleText(String extraText)

This method accepts a string on text and displays it in the window's title bar.

Parameters:

extraText - The text to be appended to some default words and displayed.

connectionLost

public void connectionLost(Throwable cause)

The method is part of the MqttSimpleCallback interface
In the event of the MQTT connection being broken the LED is set to colour amber and made to flash. The code then keeps trying to reconnect until either a successful reconnect occurs or the disconnect button is pressed. Finally the LED is stopped flashing and set to green or red depending upon whether the connect was successful or not.

Specified by:

connectionLost in interface MqttCallback

Parameters:

cause - the reason behind the loss of connection.

messageArrived

public void messageArrived(String topic,
                           MqttMessage message)

The method is part of the MqttCallback interface
Pass the message as is to the SubPanel object which will display it.

Specified by:

messageArrived in interface MqttCallback

Parameters:

topic - name of the topic on the message was published to

message - the actual message.

deliveryComplete

public void deliveryComplete(IMqttDeliveryToken token)

Description copied from interface: MqttCallback

Called when delivery for a message has been completed, and all acknowledgments have been received. For QoS 0 messages it is called once the message has been handed to the network for delivery. For QoS 1 it is called when PUBACK is received and for QoS 2 when PUBCOMP is received. The token will be the same token as that returned when the message was published.

Specified by:

deliveryComplete in interface MqttCallback

Parameters:

token - the delivery token associated with the message.

updateSubscribeTopicList

public void updateSubscribeTopicList(String topicName)

If a new topic is typed into the publish topic box then the subscribe topic box needs to be updated.

Parameters:

topicName - The topic name to add to the subscribe topic list

updatePublishTopicList

public void updatePublishTopicList(String topicName)

If a new topic is typed into the subscribe topic box then the publish topic box needs to be updated.

Parameters:

topicName - The topic name to add to the publish topic list

updateComboBoxList

public boolean updateComboBoxList(JComboBox list,
                                  String itemName)

This method handles string items in JComboBox drop downs. It checks to see if an item already exists in the list. If it doesn't, then it updates the list.

Parameters:

list - The JComboBox object to update

itemName - The value to add into the list if it doesn't already exist

Returns:

True if the item was added to the list

startTrace

public void startTrace()
                throws MqttException

This method calls the MQTT startTrace method to produce trace of the protocol flows

Throws:

MqttException

stopTrace

public void stopTrace()

This method calls the MQTT stopTrace method to stop trace of the protocol flows

writeLogln

public void writeLogln(String logdata)

Write to the history dialog window and append a newline character after the text

Parameters:

logdata - The line of text to display in the history log

writeLog

public void writeLog(String logdata)

Write to the history dialog window

Parameters:

logdata - The line of text to display in the history log

getProperties

public void getProperties(Properties props,
                          JComboBox comp,
                          String key,
                          String defValue)

Add properties from a Properties object to a JComboBox. The properties to add are selected using the specified key. Each key returns a single string, which may be further broken down into substrings delimited by the PROP_DELIM character. If no properties are found then the default value is used.

Parameters:

props - The properties object from which to get the property value.

comp - The drop down box to which the tokens within the key must be added.

key - The key to identify the property to access.

defValue - The default value for the key if no value is found.

constructPropertyValue

public String constructPropertyValue(String prop)

For a given property key construct a value to associate with the key The value can then be inserted in a properties object

Parameters:

prop - The property to construct a string value for.

Returns:

A string to write into the properties file.