Ancora su repaint

1
Ancora su repaint

• Quando si modifica la composizione di un
  container, per mostrare le variazioni NON BASTA
  chiamare la repaint(), prima occorre chiamare la
  validate().

2
Ancora su repaint

• p.addButton()
• p.validate()
• p.repaint()

3
Animazione in Java

• Problemi che possono nascere,
• e loro soluzione

4
Animazione in Java
Application
MyFrame (JFrame)
ClockPanel (JPanel)
5
ClockPanel - paintComponent
public class ClockPanel extends JPanel
public void paintComponent(Graphics g) Date
dnew Date() int secd.getSeconds()
double anglesecMath.PI/30 int
wthis.getWidth() int hthis.getHeight()
g.setColor(Color.YELLOW) g.fillRect(0,0,w,h)
g.setColor(Color.GREEN)
g.fillOval(0,0,w,h) g.setColor(Color.BLACK)
g.drawLine(w/2,h/2,
(int)(w/2(1Math.cos(angle)))
,(int)(h/2(1Math.sin(angle))))
OBSOLETO, ma funziona
6
MyFrame version 1
public class MyFrame extends JFrame
//Component initialization private void
jbInit() throws Exception contentPanenew
ClockPanel() this.setContentPane(contentPane)
contentPane.setLayout(borderLayout1)
this.setSize(new Dimension(400, 300))
this.setTitle("Frame Title") while (true)
try Thread.sleep(1000)
catch (InterruptedException ex)
contentPane.repaint() ...
Sembra ok, ma NON FUNZIONA!
7
Animazione e Threads in Java
Application
MyFrame (JFrame)
ClockPanel (JPanel)
Runner (Runnable)
8
Runner
public class Runner implements Runnable
ClockPanel cp public Runner(ClockPanel cp)
this.cpcp public void run() while
(true) try Thread.sleep(1000)
catch (InterruptedException ex)
cp.repaint()
9
MyFrame version 2
public class MyFrame extends JFrame
//Component initialization private void
jbInit() throws Exception contentPanenew
ClockPanel() this.setContentPane(contentPane)
contentPane.setLayout(borderLayout1)
this.setSize(new Dimension(400, 300))
this.setTitle("Frame Title") Runner rnew
Runner(contentPane) new Thread(r).start()
...
10
Applicativi in Java

• Come distribuire un applicativo fatto in Java?
• Vedi anche
• http//www.excelsior-usa.com/articles/java-to-exe.
  html

11
JRE? What is that? What version?

• the author of a Java program has to ensure that
  the proper version of the JRE is installed on an
  end user system.
• In a general case you may not expect that your
  end users will know what a JRE is, how to check
  its version, and how to download and install it.

12
A .bat file (or a .sh file)

• Even if you can make sure the right version of
  the JRE is properly installed on enduser systems,
  which is quite possible in a classroom or
  enterprise environment, the command line required
  to launch your Java application can be quite
  long
•     java -Xmx200m -cp whatever.jar
  -Dsome.property MyApp
• Yes, you may put that line into a batch file and
  call it runme.bat, but it looks so much easier to
  give your program to a friend, teacher or
  colleague as a single file that can be run by a
  double-click. Or, even better, enable it to be
  installed and uninstalled in a native manner
  without affecting other applications.

13
executable jar

• you can make your Java application runnable via a
  double-click by packaging it into a so called
• executable jar
• You do that by specifying the main class of your
  application, any extra jar files it may require
  and so on in the jar's manifest file
• MANIFEST.MF

Manifest-Version 1.0 Main-Class
animation.Application1
14
executable jar

• Crea un jar
• jar cvfm MyApp.jar MyApp.mf .class .gif
• Esegui un jar
• java -jar MyApp.jar
• the Java launcher will read the manifest from
  MyApp.jar and invoke the main method from the
  class specified in the Manifest.
• If you double-click that jar file on a system
  that has JRE installed, the java launcher will be
  invoked automatically.

15
JAR problems

• The major problem with executable jars is
  compatibility.
• The default JRE may be of an older version than
  is required by your application or may not have
  the necessary Java Optional Packages installed.

16
JWS - Java Web Start

• Using Java Web Start technology, standalone Java
  software applications can be deployed with a
  single click over the network. Java Web Start
  ensures the most current version of the
  application will be deployed, as well as the
  correct version of the Java Runtime Environment
  (JRE).  
• Java Web Start downloads, installs, and manages
  one or more Java Runtime Environments as required
  by the applications the user runs.

17
JWS - Java Web Start

• After running the application for the first time
  from the web page as described above, the
  application is cached. This both improves
  application performance and enables the user to
  access it without returning to the web page.
• The application is added to the Java Application
  Cache Viewer. Users can simplify running a Java
  Web Start application further by adding a
  shortcut to the desktop, by selecting Install
  Shortcuts from the Application menu in the Java
  Application Cache Viewer.

18
JWS - Java Web Start

• Developer responsibilities
• Crea un JAR file
• Crea un JNLP file
• Crea una Web Page
• Metti il tutto su un Web Server

19
JWS - JNLP file

• lt?xml version"1.0" encoding"utf-8"?gt
• ltjnlp spec"1.0 codebase"URL of application on
  your Web server"
• href"Notepad.jnlp"gt
• ltinformationgt
• lttitlegtNotepad Demolt/titlegt
• ltvendorgtSun Microsystems, Inc.lt/vendorgt
• ltoffline-allowed/gt
• lt/informationgt
• ltresourcesgt
• ltjar href"Notepad.jar"/gt
• ltj2se version"1.3"
• href"http//java.sun.com/products/
  autodl/j2se"/gt
• lt/resourcesgt
• ltapplication-desc main-class"Notepad"/gt
• lt/jnlpgt

20
JWS - Java Web Start

• Where Do You Get Java Web Start?Java Web Start
  is included in the Java Runtime Environment (JRE)
  as part of J2SE 5.0.
•  
• Vedi
• http//java.sun.com/products/javawebstart/

21
Custom wrappers

• When a Java program is invoked the operating
  system runs a Java launcher from the JRE. The
  Windows version of the JRE has separate launchers
  for command-line and GUI apps, called java.exe
  and javaw.exe respectively.
• As a result, all running Java applications have
  the same Taskbar/Alt-Tab icons and appear in the
  Windows Task Manager as either java.exe or
  javaw.exe. If you have two or more Java apps
  running, you have no means to distinguish between
  multiple instances of the standard Java launcher
  in the Task Manager.

22
Custom wrappers

• A Java wrapper in essentially a custom Java
  launcher that is also a self-extracting archive
  containing all the application's classes, jars
  and auxiliary files. Some wrapper provide
  additional features such as instant splash
  screen, stdout and stderr redirection.
• A wrapper normally looks up the JRE upon startup.
  If the JRE is not present or its version does not
  match the application's compatibility
  requirements, some wrappers may install the JRE
  (if you have included it when wrapping your
  application) and/or download and install the
  required version of the JRE.
• The most sophisticated wrappers may also setup
  file associations and create shortcuts on first
  run.

23
Custom wrappers

• Pro
• JRE version check
• JRE download or bundling
• Unique process name and icon
• No end-user training
• Contro
• Platform specific
• Desktop integration capabilities absent or very
  limited

Per una lista di Wrappers (free o commerciali)
vedi http//www.excelsior-usa.com/articles/java-to
-exe.html
24
Installers

• Installer tools may give you the following
  benefits
• Install-time JRE detection and download
• Generation of native launchers
• User-editable JVM parameter files
• Redirection of stderr and stdout for saving
  logs and exception stack traces.
• Registration of Java applications as
  Windows services and Unix daemons

Platform-centric, Multi-Platform, Cross-Platform
free IzPack, Advanced Installer for Java
25
Ahead-Of-Time Compilers

• AOT compilers are known also as "static
  compilers" and "native code compilers". The
  latter term is the most used and, as it often
  happens, the least correct from the technical
  standpoint, because JIT compilers also produce
  native code.
• An Ahead-Of-Time (AOT) compiler takes as input
  your jars and class files and produces a
  conventional native executable for the target
  platform, such as Windows EXE or Linux ELF
  binary.
• NON SERVE LA JRE!

26
Ahead-Of-Time Compilers

• Pro
• Peformance increase
• IP protection
• Better user perception
• Contro
• Disk footprint increase
• Limited applicability

1 prodotto commerciale, 1 open source (immaturo)
Vedi http//www.excelsior-usa.com/articles/java-t
o-exe.html