84 lines
2.8 KiB
XML
84 lines
2.8 KiB
XML
<section xmlns="http://docbook.org/ns/docbook"
|
|
xmlns:xlink="http://www.w3.org/1999/xlink"
|
|
xml:id="sec-language-java">
|
|
<title>Java</title>
|
|
|
|
<para>
|
|
Ant-based Java packages are typically built from source as follows:
|
|
<programlisting>
|
|
stdenv.mkDerivation {
|
|
name = "...";
|
|
src = fetchurl { ... };
|
|
|
|
buildInputs = [ jdk ant ];
|
|
|
|
buildPhase = "ant";
|
|
}
|
|
</programlisting>
|
|
Note that <varname>jdk</varname> is an alias for the OpenJDK (self-built
|
|
where available, or pre-built via Zulu). Platforms with OpenJDK not (yet) in
|
|
Nixpkgs (<literal>Aarch32</literal>, <literal>Aarch64</literal>) point to the
|
|
(unfree) <literal>oraclejdk</literal>.
|
|
</para>
|
|
|
|
<para>
|
|
JAR files that are intended to be used by other packages should be installed
|
|
in <filename>$out/share/java</filename>. JDKs have a stdenv setup hook that
|
|
add any JARs in the <filename>share/java</filename> directories of the build
|
|
inputs to the <envar>CLASSPATH</envar> environment variable. For instance, if
|
|
the package <literal>libfoo</literal> installs a JAR named
|
|
<filename>foo.jar</filename> in its <filename>share/java</filename>
|
|
directory, and another package declares the attribute
|
|
<programlisting>
|
|
buildInputs = [ jdk libfoo ];
|
|
</programlisting>
|
|
then <envar>CLASSPATH</envar> will be set to
|
|
<filename>/nix/store/...-libfoo/share/java/foo.jar</filename>.
|
|
</para>
|
|
|
|
<para>
|
|
Private JARs should be installed in a location like
|
|
<filename>$out/share/<replaceable>package-name</replaceable></filename>.
|
|
</para>
|
|
|
|
<para>
|
|
If your Java package provides a program, you need to generate a wrapper
|
|
script to run it using the OpenJRE. You can use
|
|
<literal>makeWrapper</literal> for this:
|
|
<programlisting>
|
|
buildInputs = [ makeWrapper ];
|
|
|
|
installPhase =
|
|
''
|
|
mkdir -p $out/bin
|
|
makeWrapper ${jre}/bin/java $out/bin/foo \
|
|
--add-flags "-cp $out/share/java/foo.jar org.foo.Main"
|
|
'';
|
|
</programlisting>
|
|
Note the use of <literal>jre</literal>, which is the part of the OpenJDK
|
|
package that contains the Java Runtime Environment. By using
|
|
<literal>${jre}/bin/java</literal> instead of
|
|
<literal>${jdk}/bin/java</literal>, you prevent your package from depending
|
|
on the JDK at runtime.
|
|
</para>
|
|
|
|
<para>
|
|
Note all JDKs passthru <literal>home</literal>, so if your application
|
|
requires environment variables like <envar>JAVA_HOME</envar> being set, that
|
|
can be done in a generic fashion with the <literal>--set</literal> argument
|
|
of <literal>makeWrapper</literal>:
|
|
<programlisting>
|
|
--set JAVA_HOME ${jdk.home}
|
|
</programlisting>
|
|
</para>
|
|
|
|
<para>
|
|
It is possible to use a different Java compiler than <command>javac</command>
|
|
from the OpenJDK. For instance, to use the GNU Java Compiler:
|
|
<programlisting>
|
|
buildInputs = [ gcj ant ];
|
|
</programlisting>
|
|
Here, Ant will automatically use <command>gij</command> (the GNU Java
|
|
Runtime) instead of the OpenJRE.
|
|
</para>
|
|
</section>
|