docs/BUILD.java.md: Move java build instructions out of README.

[collectd.git] / docs / BUILD.java.md

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+# Building with Java
+
+This file gives some background and hints how the *java plugin* needs to be
+configured.
+
+## Dependencies
+
+The *java plugin* requires a version of Java with *Java Native Interface* (JNI)
+**1.2** or later.
+
+## Configure and flags
+
+To determine the location of the required files of a Java installation is not an
+easy task, because the locations vary with your kernel (Linux, SunOS, …) and
+with your architecture (x86, SPARC, …) and there is no `java-config` script we
+could use. Configuration of the JVM library is therefore a bit tricky.
+
+The easiest way to use the `--with-java="${JAVA_HOME}"` option, where
+`JAVA_HOME` is usually something like:
+
+    /usr/lib/jvm/java-1.5.0-sun-1.5.0.14
+
+The configure script will then use *find(1)* to look for the following files:
+
+ *  `jni.h`
+ *  `jni_md.h`
+ *  `libjvm.so`
+
+If found, appropriate CPP-flags and LD-flags are set and the following library
+checks succeed.
+
+If this doesn't work for you, you have the possibility to specify CPP-flags,
+C-flags, LD-flags and LIBS for the *java plugin* by hand, using the following
+environment variables:
+
+ *  `JAVA_CPPFLAGS`
+ *  `JAVA_CFLAGS`
+ *  `JAVA_LDFLAGS`
+ *  `JAVA_LIBS`
+
+For example (shortened for demonstration purposes):
+
+    ./configure JAVA_CPPFLAGS="-I$JAVA_HOME/include -I$JAVA_HOME/include/linux"
+
+Adding `-ljvm` to JAVA_LIBS is done automatically, you don't have to do that.
+
+## License
+
+The *java plugin* is licensed under the *GNU General Public License, version 2*.
+Full licensing terms can be found in the file `COPYING`.