Home Page for Applet2App

Home Page for Applet2App

What is Applet2App?

Applet2App is a Java Application which can be used to convert an applet to a Java executable application. Typically, an applet requires a browser like Internet explorer, Netscape Navigator to execute. Unless it’s specifically coded, an applet can not execute as a normal Java application.

Applet2App adds the necessary wrapper files to the applet class files and creates a standalone Java 2 compliant executable jar file.

Who is the target audience for Applet2App?

Applet2App is targeted towards applet developers who also want to distribute their applets as standalone applications. Once the applet developer is ready with his applet, he can use Applet2App to create a Java 2 compliant jar file. One INI file will also be generated. This will typically have the applet attributes like the height, width etc. The applet developer can also add additional applet specific parameters to this INI file. These parameters are provided in the Applet tag of the HTML page which has the reference to the applet. The applet developer has the option of modifying the INI file directly or through Applet2App application. Then he can distribute the INI as well as the executable Jar file to the end user.

Does Applet2App cost money?

Applet2App is a “free open source” software. You can modify/customize the source code as per your requirement. But I would appreciate it if you can send me a mail giving me some feedback. Also you can suggest any modifications/wish list etc.

What is the Software requirement for Applet2App?

Applet2App requires JDK1.2 or higher to execute. It invokes jar utility which comes with JDK to create the executable Jar files. Since the concept of executable Jar file came with Java 2, so we can only use JDK 1.2 or higher for Applet2App to execute properly.

For end users, if they have JRE 2 installed on their machine, it should be enough to run the generated executable jar file. They need not have JDK installed on their machine.

How does Applet2App work?

Using Applet2App is really easy and intuitive. However, to ensure that we don’t add any extra files to the final executable, let’s do this with an example. 5 years back, I had developed an elementary game called bricks in Java as part of learning java. It has following structure.

File Name	File Type
bricks.java	Main applet java file
bricks_struct.java	Ancillary file required by bricks. java
Demoframe.java	Class file to create a Help frame
ball.gif	Static resource file required by the applet
bricks.html	HTML file which contains the applet

The Java files are stored in a package called myapp.game which means You need to store the java files in a subfolder structure like myapp/game in a root folder. Assuming you are working in windows environment and your root folder is c:\source, the bricks java files are stored in c:\source\myapp\game and ball.gif and bricks.html are stored in c:\source.

First you need to compile the program.

C:\source\> javac myapp/game/bricks.java

Note: You will get some deprecated method warnings, the reason being I have not changed the code since last 5 years J

Once all the class files are generated, you can verify whether this piece of code is working or not by clicking on c:\source\bricks.html

The contents of Bricks.html are as follows.

<HTML>

<BODY>

<P>

</P>

</CENTER>

</BODY>

</HTML>

Next you will create a workspace folder called c:\workspace which will be used to create the final executable jar file.

Create a subfolder called work inside c:\workspace

Copy the myapp subfolder from c:\source to c:\workspace\work.

Since you don’t want to package the java files in the final executable jar file, you will go to C:\workspace\work\myapp\game and delete all the java files.

Important point to remember: Preserve the package structure of the applet class file while copying the class files to the c:\workspace\work folder. This roughly translates to the following. If you have an applet inside a package called myapp.game, then copy the applet class file to c:\workspace\work\myapp\game

Next copy all the required resource files into c:\workspace\work folder assuming all the resources are accessed in the program from the root folder. However, if you use a code snippet as follows to access the image file icon.jpg,

getImage (getDocumentBase (),"res/icon.jpg");

Then copy icon.jpg to c:\workspace\work\res.In our case, since we don’t use relative folder to access resources, we will copy ball.gif to C:\workspace\work folder.

Next run the Applet2App and enter the information as follows.

Click on the File Chooser button next to Applet Class label and select the bricks class stored in C:\workspace\work\myapp\game directory.

Click on the Directory Chooser button next to Applet Root Folder and select c:\workspace\work as the root folder. You will see that the Applet class text field gets changed to myapp.game.bricks which is(and should be) same as the Applet code tag as specified in bricks.html.

Click on the Target Folder Directory Chooser button and select c:\work as the final directory where the executable jar file will be created.

Next modify the applet parameter table. Here you specify the applet parameters like width, height etc. The default parameters are as follows.

appTitle: Title of the Application which will appear on the title bar of the application

appIcon: Application icon, I copied a file called bricks.jpg in c:\workspace folder and specified bricks.jpg as the application icon.

appWidth: Width of the applet, same as the width parameter in the applet tag of bricks.html.

appHeight: Height of the applet, same as the height parameter in the applet tag of bricks.html.

appStatusbar: this is used to specify if the status bar will be viewable or not. Default is “yes’.

Apart from the above parameters, you can add your own applet specific parameters (found as the PARAM=VALUE pairs in the APPLET Tag). Our application does not use any extra parameters. So we didn’t define any other parameters.

Now you should click on “Create Jar” button. Before clicking on the “Create Jar” button, ensure that jar utility which comes as part of the JDK, is included in PATH. A Jar file(bricks.jar) and an INI (bricks.ini) should be generated in c:\workspace folder. Delete c:\workspace\work folder. This is no longer required.

Now you should be having only 3 files in c:\workspace folder. These are

bricks.jar: the executable Jar file

bricks.ini: the configuration file for bricks.jar

bricks.jpg: the application icon for bricks.jar

Click on bricks.jar file and you should see a screen similar to the following screen.

One pleasant side effect is, you can use the same executable jar file as the applet archive file in the original html page. In our case, we need to modify bricks.html (modifications marked in RED) as follows.

<HTML>

<BODY>

<P>

</P>

</CENTER>

</BODY>

</HTML>

Delete all the class files and copy the bricks.jar file to the same folder as bricks.html. Then click on bricks.html file. The applet should start running.

Can I convert my applet to a Windows executable file?

You can not use Applet2App to create the Windows executable. However, I have developed an application called JarWrapper which can be used to wrap an executable jar file in a Windows exe file. You might want to check the FAQ to find out whether you need it. However, JarWrapper is not a Open Source Software. But it’s a freeware. You can download it and use it to convert your executable jar files to windows executables absolutely free of cost.

Once you have created the executable Jar file from your applet class files, you can use JarWrapper to wrap it in a Windows executable file.

How do I distribute my resource files apart from the executable Jar file?

Resource files can be divided into two categories.

i. Configurable resources

ii. Static resources

Configurable resources are resources which end users can configure /customize as per their requirements. Typically these are INI files/ properties files which can be modified by the end user. Ideally these should be distributed separately along with the executable Jar file in a deployable package to the end user.

Static resources are resources like images/graphics, splash screens, data files etc. which should not be tampered by the end user. These should be embedded in the final executable jar file. The applet developer should write his code in such a way that even though the static resource is embedded in the jar file, the application should be able to find it out. One example could be as follows.

Let’s say, in the existing applet code, you have the following piece of code which creates an ImageIcon from a JPG file as follows.

ImageIcon anIcon = new ImageIcon ("res/icon.jpg");

If the above code is present in you’re applet code, then you can not deploy icon.jpg file embedded inside your executable jar file. This won’t work. But you can release it as a separate configurable resource as res/icon.jpg. However, if you do the following modification and recompile your applet code, then you can embed icon.jpg file in the res subfolder of executable jar file.

ImageIcon anIcon = new ImageIcon(new URL(getDocumentBase (), "res/icon.jpg"));

The thumb rule is: if you want to access a static resource embedded inside the executable jar file, then get the URL of the JAR file’s Root by calling getDocumentBase() or getCodeBase() and then use the relative path of the resource inside the JAR file to access it.

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