SQuirreL SQL uses an Ant based built system, see http://ant.apache.org/. To build SQuirreL you need to download Ant version 1.9.3 or higher from here: http://ant.apache.org/bindownload.cgi
Then open a cmd/shell window and change directory to <squirrel-git-root>/sql12/. Form there execute <ant-home>/bin/ant. This will generate the directory <squirrel-git-root>/sql12/output/ where all the build artefacts (installer jars, plainzip packages) are placed.
The build script itself is located at <squirrel-git-root>/sql12/build.xml and contains a few more than 200 lines of code.
With the restructuring of the build system went a new directory structure:
<squirrel-git-root>/sql12/core/: Contains the code of SQuirreL's base application..<squirrel-git-root>/sql12/plugins/: Contains all Plugins.<squirrel-git-root>/sql12/launcher/: Contains the basis of SQuirreL's start scripts in a way they are needed for building the installer packages.<squirrel-git-root>/sql12/plainZipScript/: Scripts for plain zip distributions. If copied to the launcher directory these scripts are able to start SQuirreL without installation.<squirrel-git-root>/sql12/output/dist/ as SQuirreL's home directory (command line: -home <squirrel-git-root>/sql12/output/dist/).<squirrel-git-root>/sql12/core/lib in your classpath<squirrel-git-root>/sql12/pluins/laf/ and <squirrel-git-root>/sql12/pluins/skinlf-theme-packs/ in your classpath<squirrel-git-root>/sql12/core/src/ and <squirrel-git-root>/sql12/plugins/<plugin>/src/