setupMatR.m

% Not sufficient that these classes are in the dynamic path
function setupMatR()

jpath = javaclasspath('-static');
[~,jars] = cellfun(@(x) fileparts(x),jpath,'uni',0);

if any(strcmp(jars,'REngine')) && any(strcmp(jars,'RserveEngine'))
   % Already in user's static javaclasspath
else
   path = fileparts(which('MatR'));
   
   % TODO, check existence, download otherwise
   javaaddpathstatic([path filesep 'lib/REngine.jar']);
   javaaddpathstatic([path filesep 'lib/RserveEngine.jar']);
end

function javaaddpathstatic(file, classname)
%JAVAADDPATHSTATIC Add an entry to the static classpath at run time
%
% javaaddpathstatic(file, classname)
%
% Adds the given file to the static classpath. This is in contrast to the
% regular javaaddpath, which adds a file to the dynamic classpath.
%
% Files added to the path will not show up in the output of
% javaclasspath(), but they will still actually be on there, and classes
% from it will be picked up.
%
% Caveats:
%  * This is a HACK and bound to be unsupported.
%  * You need to call this before attempting to reference any class in it,
%    or Matlab may "remember" that the symbols could not be resolved. Use
%    the optional classname input arg to let Matlab know this class exists.
%  * There is no way to remove the new path entry once it is added.

% Andrew Janke 20/3/2014 http://stackoverflow.com/questions/19625073/how-to-run-clojure-from-matlab/22524112#22524112

parms = javaArray('java.lang.Class', 1);
parms(1) = java.lang.Class.forName('java.net.URL');
loaderClass = java.lang.Class.forName('java.net.URLClassLoader');
addUrlMeth = loaderClass.getDeclaredMethod('addURL', parms);
addUrlMeth.setAccessible(1);

sysClassLoader = java.lang.ClassLoader.getSystemClassLoader();

argArray = javaArray('java.lang.Object', 1);
jFile = java.io.File(file);
argArray(1) = jFile.toURI().toURL();
addUrlMeth.invoke(sysClassLoader, argArray);

if nargin > 1
   % load the class into Matlab's memory (a no-args public constructor is expected for classname)
   eval(classname);
end