nixpkgs-suyu/doc/languages-frameworks/java.xml
Vladimír Čunát ef21e5ee60 nixpkgs manual: split languages into separate files
There's no change in content except for amending the title of the
section to mention "frameworks", as e.g. I don't consider Qt a language,
and it's likely there will be more of similar cases in future.

To be certain, I checked diff of the generated HTMLs.
2015-12-19 16:08:00 +01:00

84 lines
2.6 KiB
XML
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

<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.</para>
<para>JAR files that are intended to be used by other packages should
be installed in <filename>$out/share/java</filename>. The OpenJDK has
a stdenv setup hook that adds any JARs in the
<filename>share/java</filename> directories of the build inputs to the
<envar>CLASSPATH</envar> environment variable. For instance, if the
package <literal>libfoo</literal> installs a JAR named
<filename>foo.jar</filename> in its <filename>share/java</filename>
directory, and another package declares the attribute
<programlisting>
buildInputs = [ jdk libfoo ];
</programlisting>
then <envar>CLASSPATH</envar> will be set to
<filename>/nix/store/...-libfoo/share/java/foo.jar</filename>.</para>
<para>Private JARs
should be installed in a location like
<filename>$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>It is possible to use a different Java compiler than
<command>javac</command> from the OpenJDK. For instance, to use the
Eclipse Java Compiler:
<programlisting>
buildInputs = [ jre ant ecj ];
</programlisting>
(Note that here you dont need the full JDK as an input, but just the
JRE.) The ECJ has a stdenv setup hook that sets some environment
variables to cause Ant to use ECJ, but this doesnt work with all Ant
files. Similarly, you can 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>