lib/java.nit

   1 # This file is part of NIT ( http://www.nitlanguage.org ).
   2 #
   3 # Copyright 2014 Alexis Laferrière <alexis.laf@xymus.net>
   4 #
   5 # Licensed under the Apache License, Version 2.0 (the "License");
   6 # you may not use this file except in compliance with the License.
   7 # You may obtain a copy of the License at
   8 #
   9 #     http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 # Unless required by applicable law or agreed to in writing, software
  12 # distributed under the License is distributed on an "AS IS" BASIS,
  13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16
  17 # Supporting services for the FFI with Java
  18 module java is
  19         c_compiler_option("-I $(JAVA_HOME)/include/")
  20         c_linker_option("-L $(JNI_LIB_PATH) -ljvm")
  21 end
  22
  23 import jvm
  24
  25 redef class Sys
  26         private var jvm_cache: nullable JavaVM = null
  27         private var jni_env_cache: nullable JniEnv = null
  28
  29         # Default Java Virtual Machine to use (will be instanciated using
  30         # `create_default_jvm` if not already set)
  31         fun jvm: JavaVM
  32         do
  33                 if jvm_cache == null then create_default_jvm
  34                 return jvm_cache.as(not null)
  35         end
  36
  37         # Sets the current default Java Virtual Machine (use with `jni_env=`)
  38         fun jvm=(jvm: JavaVM) do jvm_cache = jvm
  39
  40         # Current main `JniEnv`
  41         # FIXME support threaded Java
  42         fun jni_env: JniEnv
  43         do
  44                 if jni_env_cache == null then create_default_jvm
  45                 return jni_env_cache.as(not null)
  46         end
  47
  48         # Sets the current default JNI env (use with `jvm=`)
  49         fun jni_env=(jni_env: JniEnv) do jni_env_cache = jni_env
  50
  51         # Called by `jvm` and `jni_env` to instanciate a Java Virual Machine.
  52         # Used mostly for FFI with Java.
  53         protected fun create_default_jvm
  54         do
  55                 var builder = new JavaVMBuilder
  56
  57                 # By default, look for Java classes in a jar file the same dir as the executable
  58                 builder.options.add "-Djava.class.path={sys.program_name}.jar"
  59
  60                 var jvm = builder.create_jvm
  61                 assert jvm != null else print "JVM creation failed"
  62
  63                 self.jvm = jvm
  64                 self.jni_env = builder.jni_env.as(not null)
  65         end
  66 end