On 09/03/2010, Jörg Schaible <joerg.schai...@gmx.de> wrote:
> sebb wrote at Dienstag, 9. März 2010 02:10:
>
>
> > I've done some investigations.
> >
> > Maven can happily compile code with Java 1.3 or 1.4 etc. even when
> > Maven itself runs under Java 1.5+ [1]
> >
> > This can be done by adding the following to the component POM:
> >
> > <build>
> > <plugins>
> > <plugin>
> > <groupId>org.apache.maven.plugins</groupId>
> > <artifactId>maven-compiler-plugin</artifactId>
> > <configuration>
> > <fork>true</fork>
> > <executable>${JAVA_1_3_HOME}/bin/javac</executable>
> > <compilerVersion>${maven.compile.source}</compilerVersion>
> > </configuration>
> >
> > The variable JAVA_1_3_HOME can either be defined as:
> > + an environment variable
> > + added to settings.xml or
> > + defined on the command line
> > (the above are processed in order, the last one takes precedence)
> >
> > SureFire also allows a different JVM to be used:
> >
> > <artifactId>maven-surefire-plugin</artifactId>
> > <configuration>
> > <jvm>${JAVA_1_4_HOME}/bin/java</jvm>
> >
> > However, the current version of Surefire (2.4.3) does not run under
> > 1.3.1; the latest version that seems to support 1.3 is Surefire 2.2,
> > so the parent version needs to be overridden with that in the
> > component pom.
> >
> > So projects requiring Java 1.3 or 1.4 can be compiled and tested under
> > Java 1.5+
> >
> > But how best to implement this?
> >
> > It's important that the POMS still work even if local system only has
> > (say) Java 1.5, but it would be nice if Maven automatically chose the
> > appropriate compiler if it is available (according to the environment
> > variables).
> >
> > It would be neat if this could be implemented in the parent pom, but I
> > don't know enough about profiles to know if this is possible. Can the
> > parent pom refer to variables defined in a child pom?
> >
> > What would be ideal is to activate the settings when the component
> > profile specifies compiler.source which is different from the JVM
> > which is running Maven. If the appropriate environment variable
> > exists (i.e. the compiler exists) then process the settings, otherwise
> > report a warning and continue.
> >
> > Otherwise, if the overrides can at least be enabled by setting a
> > command-line parameter, that would be OK.
> >
> > 1]
> > http://maven.apache.org/plugins/maven-compiler-plugin/examples/compile-
> using-different-jdk.html
>
>
> Another solution should be the animal sniffer:
> http://mojo.codehaus.org/animal-sniffer-maven-plugin/
>
> This should ensures that the generated byte code is using only the API of a
> previously generated signature. There are already signatures for the
> different JREs. This way you could even check for JRE 1.3 compatibility.
>
Animal looks like a lot of work; and you have to create signatures for
each release (why are these not included as part of the plugin?)
Using a profile looks to be fairly simple in comparison.
> - Jörg
>
>
>
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