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Diffstat (limited to 'nixpkgs/doc/languages-frameworks/java.xml')
| -rw-r--r-- | nixpkgs/doc/languages-frameworks/java.xml | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/nixpkgs/doc/languages-frameworks/java.xml b/nixpkgs/doc/languages-frameworks/java.xml new file mode 100644 index 000000000000..bf0fc4883922 --- /dev/null +++ b/nixpkgs/doc/languages-frameworks/java.xml @@ -0,0 +1,63 @@ +<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 { ... }; + + nativeBuildInputs = [ 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>$out/share/java</filename>. JDKs have a stdenv setup hook that add any JARs in the <filename>share/java</filename> directories of the build inputs to the <envar>CLASSPATH</envar> environment variable. For instance, if the package <literal>libfoo</literal> installs a JAR named <filename>foo.jar</filename> in its <filename>share/java</filename> directory, and another package declares the attribute +<programlisting> +buildInputs = [ libfoo ]; +nativeBuildInputs = [ jdk ]; +</programlisting> + then <envar>CLASSPATH</envar> will be set to <filename>/nix/store/...-libfoo/share/java/foo.jar</filename>. + </para> + + <para> + Private JARs should be installed in a location like <filename>$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> +nativeBuildInputs = [ 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> +nativeBuildInputs = [ gcj ant ]; +</programlisting> + Here, Ant will automatically use <command>gij</command> (the GNU Java Runtime) instead of the OpenJRE. + </para> +</section> |