Rhino JavaScript to EXE with launch4j

Originally published on: Sat, 24 Jul 2010

After successfully compilng a Rhino JavaScript program to a Java class file ( Compiling Rhino JavaScript to Java), I wanted to see if I could then convert such a class file to a Windows executable (EXE) file using launch4j.

Let's start by creating a new, self-contained JS file that does not contain any runtime calls to load().

The script dir_scan.js uses a recursive function scanDir() to traverse a directory, tallying up all of the consumed file space into a map named mapOfDirs.

After the traversal, the keys from mapOfDirs are isolated into an array called mapKeys. The array is then sorted. A closure function is used in the sort invocation that sorts the array based on the corresponding value in the map. When the call to mapKeys.sort() completes, the array then holds the keys in sorted, ascending order by the computed filesize of the elements of the given directory.

dir_scan.js

// dir_scan // // Add up the sizes of visible files in the // specified directory tree and write the sizes // of each to the console. The directory containing // the most visible files will be listed at the top. // // Copyright 2010 by James K. Lawless // See MIT/X11 license at // http://www.mailsend-online.com/wp/license.php importPackage(java.io); function scanDir(dir) { var lst=new File(dir).listFiles(); var i, fil, total, dirSize; total=0; for(i=0;i<lst.length;i++) { // If it's a directory, recursive call // this method to compute the size // of the child directory fil=lst[i]; if(fil.isDirectory()) { dirSize=scanDir(fil); mapOfDirs[fil.getAbsolutePath()]=dirSize; total+=dirSize; } else { total+=fil.length(); } } return total; } function padLeft(x) { var blank=" "; var s=x+""; return blank.substring(1,blank.length-s.length) + s; } function mainFlow(args) { if(args.length==0) { // Once we compile and convert to an EXE, this // syntax helper will be more fitting. To test interactively, // issue the command: // java -jar js.jar dir_scan.js path-to-scan print("Syntax: dir_scan path-to-scan"); return; } var i; // Create a map to hold the contents of all the items in // each directory mapOfDirs=new Object(); grandTotal=scanDir(args[0]); // now, let's sort the map using a work array // "mapKeys" to hold the keys sorted by the map // values. mapKeys=[]; for(i in mapOfDirs) mapKeys.push(i); mapKeys.sort( function (a,b) { var x,y; x=mapOfDirs[a]; y=mapOfDirs[b]; if(x<y) { return -1; } else if(x==y) { return 0; } else return 1; }); for(i=0;i<mapKeys.length;i++) { k=mapKeys[i]; print(padLeft(mapOfDirs[k]) + " : " + k); } print(padLeft(grandTotal) + " : " + arguments[0]); } var mapOfDirs, mapKeys, grandTotal; mainFlow(arguments);

You can invoke the script by using the following command-line:

java -jar js.jar dir_scan.js c:\j\rhino

The first argument is the directory that you want to scan. I supplied my Rhino installation directory. The resulting output ends with the following 10 lines:

      918278 : c:\j\rhino\javadoc\org\mozilla
     1216905 : c:\j\rhino\javadoc
     2189449 : c:\j\rhino\src\org\mozilla\javascript
     2304840 : c:\j\rhino\org\mozilla\javascript
     2306469 : c:\j\rhino\src\org
     2306469 : c:\j\rhino\src\org\mozilla
     2309824 : c:\j\rhino\src
     2349099 : c:\j\rhino\org
     2349099 : c:\j\rhino\org\mozilla
    12425293 : c:\j\rhino

After testing the script, the next step was to convert the script to a Java class file. I had run into issues in my first attempt at using launch4j until I had packaged my classes properly. When compiling dir_scan.js, I added the -package directive to force the generated class to be bound to the class com.mailsend_online.

java org.mozilla.javascript.tools.jsc.Main -package com.mailsend_online dir_scan.js

The new output class file was then generated into the directory com\mailsend_online. I tested the class file:

java com.mailsend_online.dir_scan c:\j\rhino

I received the expected output. The next step was to jar up the class as a preparatory step for the launch4j process. I created the manifest.mf file first: manifest.mf

Manifest-Version: 1.0 Main-Class: com.mailsend_online.dir_scan

I tried to place the class into a jar by itself, but I ran into some CLASSPATH issues. I decompressed js.jar and js-14.jar into a tree of files starting in the current directory. I then included all of these files in my output dir_scan.jar file along with com\mailsend_online\dir_scan.class using the following command-line:

jar -cfm dir_scan.jar manifest.mf com\*.* org\*.*

Last year, when I wrote about converting using launch4j on a pure Java program ( Java in a Windows EXE with launch4j ), I used the GUI interface to bind the jar to an EXE. When I tried to do that directly this time, I was unable to make the resulting EXE appear.

I saved the configuration to a file called dir_scan.xml. I then changed the headerType element to console

dir_scan.xml

<launch4jConfig> <dontWrapJar>false</dontWrapJar> <headerType>console</headerType> <jar>c:\j\rhino\dir_scan.jar</jar> <outfile>dir_scan.exe</outfile> <errTitle></errTitle> <cmdLine></cmdLine> <chdir></chdir> <priority>normal</priority> <downloadUrl>http://java.com/download</downloadUrl> <supportUrl></supportUrl> <customProcName>false</customProcName> <stayAlive>false</stayAlive> <manifest></manifest> <icon></icon> <jre> <path></path> <minVersion>1.6.0</minVersion> <maxVersion></maxVersion> <jdkPreference>preferJre</jdkPreference> </jre> </launch4jConfig>

I then used the launch4j command-line utility to build the EXE.

C:\progra~1\launch4j\launch4jc dir_scan.xml
launch4j: Compiling resources
launch4j: Linking
launch4j: Wrapping
launch4j: Successfully created C:\j\rhino\dir_scan.exe

A quick test of the EXE yielded the expected results: