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package cbt;
import java.io.*;
import java.lang.reflect.*;
import java.net.*;
import java.nio.*;
import java.nio.file.*;
import java.util.*;
import java.util.concurrent.ConcurrentHashMap;
/**
* This launcher allows to use Nailgun without loading anything else permanenetly into its
* classpath except for the launcher itself. That's why it is written in Java without
* dependencies outside the JDK.
*
* The main method loads the given class from the given class path, calls it's main
* methods passing in the additional arguments.
*/
public class NailgunLauncher{
/**
* Persistent cache for caching classloaders for the JVM life time. Can be used as needed by user
* code to improve startup time.
*/
public static ConcurrentHashMap<String,ClassLoader> classLoaderCache =
new ConcurrentHashMap<String,ClassLoader>();
public static void main(String[] args) throws ClassNotFoundException,
NoSuchMethodException,
IllegalAccessException,
InvocationTargetException,
MalformedURLException {
if (args.length < 3) {
System.out.println("usage: <main class> <class path> <... args>");
} else {
// TODO: cache this classloader, but invalidate on changes
String[] cp = args[1].split(File.pathSeparator);
URL[] urls = new URL[cp.length];
for(int i = 0; i < cp.length; i++){ urls[i] = new URL("file:"+cp[i]); }
String[] newArgs = new String[cp.length - 2];
for(int i = 2; i < cp.length; i++){ newArgs[i] = args[i]; }
new URLClassLoader( urls )
.loadClass(args[0])
.getMethod("main", String[].class)
.invoke( null/* _cls.newInstance()*/, (Object) newArgs );
}
}
}
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