How can I use the janino compiler to compile a simple java source from string to bytecode in byte array?
I have so far been trying to make sense of the janino documentation here (under SimpleCompiler) and here on how to go about compiling one single java source into one single class in bytecode format but I don't think I am doing it right.
So far my naive approach looks like this:
private void testJanino() {
String cn = "Arne";
SimpleCompiler sc = new SimpleCompiler();
try {
sc.cook("public class Arne{ public float doWork(){return 42.0f;}}");
InputStream is = sc.getClassLoader().getResourceAsStream(cn);
if (null != is) {
int len = is.available();
byte[] ar = new byte[len];
System.out.println("SZ:" + len);
int r = is.read(ar);
System.out.println("READ:" + r);
} else {
System.out.println("NO IS");
}
} catch (CompileException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
Output is NO IS suggesting that I am trying to use it incorrectly.
So what should I be doing instead?
EDIT: I have been going at this non-stop and I just cant seem to get what I want. Here is an attempt to use the janino UnitCompiler class:
private String mClassName = "Arnulf";
private String mCode = "public class " + mClassName + "{ public float doWork(){return 42.0f;}}";
private void testJanino2() {
try {
InputStream is = new ByteArrayInputStream(mCode.getBytes(StandardCharsets.UTF_8));
Scanner s = new Scanner(mClassName, is);
Parser p = new Parser(s);
Java.CompilationUnit compilationUnit = p.parseCompilationUnit();
IClassLoader iClassLoader = new LOLClassLoader(null);
UnitCompiler uc = new UnitCompiler(compilationUnit, iClassLoader);
uc.compileUnit(false, false, false);
} catch (CompileException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
Where LOLClassLoader is a simple "log everything, do nothing" kind of class that extends IClassLoader.
This ends up in a nullpointer like this:
java.lang.NullPointerException
at org.codehaus.janino.UnitCompiler.compile2(UnitCompiler.java:429)
at org.codehaus.janino.UnitCompiler.compile2(UnitCompiler.java:393)
at org.codehaus.janino.UnitCompiler.access$400(UnitCompiler.java:185)
at org.codehaus.janino.UnitCompiler$2.visitPackageMemberClassDeclaration(UnitCompiler.java:347)
at org.codehaus.janino.Java$PackageMemberClassDeclaration.accept(Java.java:1139)
at org.codehaus.janino.UnitCompiler.compile(UnitCompiler.java:354)
at org.codehaus.janino.UnitCompiler.compileUnit(UnitCompiler.java:322)
at com.mypackage.backend.MyServlet.testJanino2(MyServlet.java:60)
at com.mypackage.backend.MyServlet.doPost(MyServlet.java:208)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:511)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1166)
at com.google.appengine.api.socket.dev.DevSocketFilter.doFilter(DevSocketFilter.java:74)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.ResponseRewriterFilter.doFilter(ResponseRewriterFilter.java:127)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.HeaderVerificationFilter.doFilter(HeaderVerificationFilter.java:34)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.api.blobstore.dev.ServeBlobFilter.doFilter(ServeBlobFilter.java:63)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.apphosting.utils.servlet.TransactionCleanupFilter.doFilter(TransactionCleanupFilter.java:43)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.StaticFileFilter.doFilter(StaticFileFilter.java:125)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectRequest(DevAppServerModulesFilter.java:366)
at com.google.appengine.tools.development.DevAppServerModulesFilter.doDirectModuleRequest(DevAppServerModulesFilter.java:349)
at com.google.appengine.tools.development.DevAppServerModulesFilter.doFilter(DevAppServerModulesFilter.java:116)
at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1157)
at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:388)
at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:182)
at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:765)
at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:418)
at com.google.appengine.tools.development.DevAppEngineWebAppContext.handle(DevAppEngineWebAppContext.java:98)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at com.google.appengine.tools.development.JettyContainerService$ApiProxyHandler.handle(JettyContainerService.java:491)
at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:152)
at org.mortbay.jetty.Server.handle(Server.java:326)
at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:542)
at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:938)
at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:755)
at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:218)
at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:404)
at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:409)
at org.mortbay.thread.QueuedThreadPool$PoolThread.run(QueuedThreadPool.java:582)
Any help or tips are welcomed at this point.
Thanks!
