1 files changed, 48 insertions, 0 deletions
diff --git a/nailgun_launcher/NailgunLauncher.java b/nailgun_launcher/NailgunLauncher.java
new file mode 100644
index 0000000..a6858d9
--- /dev/null
+++ b/nailgun_launcher/NailgunLauncher.java
@@ -0,0 +1,48 @@
+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 it's classpath.
+The main method loads the given class from the given class math, 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){
+		try{
+			if(args.length < 3){
+				System.out.println("usage: <main class> <class path> <... args>");
+			} else {
+				URLClassLoader cl = new URLClassLoader( // TODO: cache this classloader, but invalidate on changes
+					Arrays.stream(
+						args[1].split(File.pathSeparator)
+					).filter( cp -> !(cp == "") ).map( cp -> {
+						try { return new URL("file:" + cp); }
+						catch(MalformedURLException e) { throw new RuntimeException(e); }
+					}).toArray(URL[]::new)
+				){
+					public String toString(){
+						String suffix = "";
+						if(getParent() != ClassLoader.getSystemClassLoader())
+							suffix = ", "+getParent();
+						return "URLClassLoader(" + Arrays.toString(getURLs()) + suffix +")";
+					}
+				};
+				cl  .loadClass( args[0] )
+					.getMethod( "main", String[].class )
+					.invoke(
+						null/* _cls.newInstance()*/,
+						(Object) Arrays.stream(args).skip(2).toArray( String[]::new )
+					);
+			}
+		} catch (Exception e) { throw new RuntimeException(e); }
+	}
+}