Java ENet Binding

A Swig binding of ENet for Java (& Processing)

Tutorial

Ensure you already have the ENet package installed.

Download and install Swig. To install, after downloading, go to ./swig-VERSION/Doc/Manual/Preface.html and view it in your websbrowser. From here follow the installation instructions.

For Swig-4.2.1, these instructions are as follows:

You must use GNU make to build and install SWIG.

PCRE2 needs to be installed on your system to build SWIG, in particular pcre2-config must be available. If you have PCRE2 headers and libraries but not pcre2-config itself or, alternatively, wish to override the compiler or linker flags returned by pcre2-config, you may set PCRE2_LIBS and PCRE2_CFLAGS variables to be used instead. And if you don't have PCRE2 at all, the configure script will provide instructions for obtaining it.

Get PCER2 by going here and downloading the .tar.gz file then extracting it: https://github.com/PCRE2Project/pcre2/releases

Now, before installing PCER2 you may also need bzlib, so check by running sudo yum whatprovides */bzlib.h. If it does not exist run sudo apt install libbz2-dev

Also install sudo apt-get install libreadline-dev

Once you have it extracted follow the instructions here to install it. For version 2.10.44 this should simply be the following (done its respective extracted root folder):

./configure --prefix=/usr                       \
            --docdir=/usr/share/doc/pcre2-10.44 \
            --enable-unicode                    \
            --enable-jit                        \
            --enable-pcre2-16                   \
            --enable-pcre2-32                   \
            --enable-pcre2grep-libz             \
            --enable-pcre2grep-libbz2           \
            --enable-pcre2test-libreadline      \
            --disable-static                    &&
make

And run sudo make install to finish the install for pcre2.

Now you can install Swig (done its respective extracted root folder):

./configure
make

And finally run sudo make install to finish the install for Swig.

To ensure it installed, check with the following command:

make -k check

Now that you have Swig and Enet properly installed, take note of Enets location, usually one of the following:

• /usr/include/enet/enet.h
• /usr/local/include/enet/enet.h

Requirements

sudo apt-get update
sudo apt-get install default-jdk
sudo apt-get install libenet-dev

From here we can develop the Swig command, below is what it turned out to be for myself, but it could be different for you.

swig -java -package enet -outdir ./enet -I/usr/include -c++ enet.i

Alternatively, use the included enet implementation

swig -java -package enet -outdir ./enet -c++ enet.i

Now, once you run this, a generated enet_wrap.cxx should have been generated.

Compile this wrapper file.

Generic

g++ -fPIC -c enet_wrap.cxx \
    -I/path/to/jdk/include \
    -I/path/to/jdk/include/linux \
    -I/usr/include/enet

An example

g++ -fPIC -c enet_wrap.cxx \
    -I/usr/lib/jvm/java-11-openjdk-amd64/include \
    -I/usr/lib/jvm/java-11-openjdk-amd64/include/linux \
    -I/usr/include/enet

Link to shared library

g++ -shared enet_wrap.o -o libenetjni.so -lenet

Now that we have this, we must compile into a JAR

javac -source 1.8 -target 1.8 -d bin ./enet/*.java ./enet/enetJNI.java
jar cf ENet.jar -C bin .

From here all you have to do is place the libenetjni.so & ENet.jar files into the code/ directory.

Load the package into your project manually via System.loadLibrary("enetjni"); and access normally.