SWTLoader: run SWT programs with a double click, v.1.01

Introduction

SWT and SwingWT-based programs, as well as all other Java programs with native libraries, are often tricky to deploy.
Because the native libraries are needed, the users have either to install those in a directory in the PATH (assuming that they know what it is) or a platform-specific installer or script must be deployed.
Jar files would be preferrable, because a double-click would launch them on most platforms, but the Java Virtual Machine cannot use native libraries in Jars, in facts you'll have to set the -Djava.library.path commandline option in most cases.
SWTLoader is an elegant hack to avoid all this, allowing you to deploy self-contained, self-extracting native libraries such as SWT in a single Jar file.

How to use it

You can use SWTLoader with three easy steps:

import net.moioli.swtloader.*; in the class with the main() method;
Create a new SWTLoader as the first instruction in the main method:

public static void main(String[] args){
new SWTLoader("packagename.jar");
...

Include in the Jar file the needed .dll, .so or .jnilib files. Ant example:

<target name="demo-SwingWT-linux" >

            <javac srcdir="${srcDir}" destdir="${buildDir}">

            <classpath>

            <pathelement path="swt.jar"/>

            <pathelement path="swt-pi.jar"/>

            </classpath>

            <include name="**/*.java" />

            </javac>

            <unjar src="$swt.jar" dest="${buildDir}"/>

            <unjar src="$swt-pi.jar" dest="${buildDir}"/>

            <copy todir="${buildDir}">

            <fileset dir="${swtLinuxLibDir}/">

            <include name="*.so"/>

            </fileset>

            </copy>

            <jar destfile="${buildDir}/demo-SwingWT-linux.jar" basedir="${buildDir}">

            <fileset dir="${buildDir}" >

            <include name="**/*.class" />

            <include name="**/*.so"/>

            </fileset>

            <manifest>

            <attribute name="Main-Class" value="SWTDemo"/>

            </manifest>

            </jar>

            </target>

Users, double-clicking or using the command java -jar packagename.jar will get a fully functional SWT-enabled JVM.

How does it work?

The inner workings of the script are quite easy: first, it creates a temporary directory, then it unpacks the needed files and finally it re-invokes the JVM with the needed -D option. Note that you'll have only one JVM running at a time: the first VM instance will be terminated safely.
Also, if SWT is already loadable, none of these actions will be performed.

Get it

Here! (sources only)

License

SWTLoader is published under the GPL license. If you need a non-GPL'd version (eg. for commercial purposes) email me: silvio at moioli dot net

Feedback

Feedback (both positive and negative) is always welcome. Please write me at: silvio at moioli dot net
Italian-speaking people can also visit my site.

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