Classloading problems. Loading from a ZIP.

[DrEinsteinium]

Hey guys, I am working on WikiLinkLib, a small zip library of class files implementing my Plugin interface. I am making it so this zip file will not load with all other mods, but my mod will load it AFTER it downloads and updates (if needed). To achieve this I am trying to use a classloader that loads all classes from a zip but I am getting an annoying error. I have tried everything I can think of but for some reason I can not figure it out.

 

Here is my LibraryHandler class. This class essentially pulls the class files from the ZIP archive and sends them to the class loading method inside of my PluginManager.

 

public class LibraryHandler
{
public static void loadLibClasses(File dir)
{
	try
	{
		ZipEntry entry = null;
		File file = new File(dir.getCanonicalFile() + File.separator + "WikiLinkLib.zip");
		final FileInputStream fileIO = new FileInputStream(file);
		final ZipInputStream zipIO = new ZipInputStream(fileIO);

		while(true)
		{
			entry = zipIO.getNextEntry();

			if(entry == null)
			{
				fileIO.close();
				break;
			}

			final String entryName = entry.getName();
			final File entryFile = new File(entryName);
			final String pluginName = entryFile.getName();
			final ClassLoader loader = WikiLink.class.getClassLoader();

			if(!entry.isDirectory() && pluginName.startsWith("Plugin") && pluginName.endsWith(".class"))
			{					
				PluginManager.initWikiLinkLib(loader, pluginName, entryFile.getPath().replace(File.separator, "."));
			}
		}
	}
	catch(Exception e)
	{
		e.printStackTrace();
	}
}
}

 

Here is the method in my PluginManager that loads(or is supposed to) the classes.

 

    private static void addPlugin(final ClassLoader classLoader, final String pluginName, final String packageName)
    {
        if (pluginName.equals("PluginManager.class") || pluginName.equals("Plugin.class"))
        {
            return;
        }

        final String pluginClassName = packageName.replace(".class", "");

        try
        {
            final Class<?> pluginClass = classLoader.loadClass(pluginClassName);
            
            if (pluginClass != null)
            {
                Class<?> clz = pluginClass;
                boolean isPlugin = false;

                do
                {
                    for (final Class<?> i : clz.getInterfaces())
                        if (i == Plugin.class)
                        {
                            isPlugin = true;
                            break;
                        }

                    clz = clz.getSuperclass();
                }
                while (clz != null && !isPlugin);

                if (!isPlugin)
                {
                    return;
                }

                final Plugin plugin = (Plugin) pluginClass.newInstance();
                
                if (plugin != null)
                {
                    INSTANCE.plugins.add(plugin);

                    if (plugin instanceof IFuelHandler)
                    {
                        GameRegistry.registerFuelHandler((IFuelHandler) plugin);
                    }
                }
            }
        }
        catch (final Exception ex)
        {
        WikiLink.LogHelper.info("Cannot load class " + pluginClassName);
        ex.printStackTrace();
        }
    }

 

For the ClassLoader I am using the ClassLoader of my main mod file WikiLink. This will essentially just call the ClassLoader for Forge. I am not sure if this is how it is supposed to work but I don't know any other way.

 

Here is the stacktrace: http://pastebin.com/jaFkbDWK

The only Plugin file in my ZIP archive is co.einsteinium.wikilinklib.plg.PluginMinecraftWiki.class

 

If there is anyone that can enlighten me on classloading w/ forge then I would really appreciate it. This is the first time I've really ever messed with classloading so I am a bit new.

 

Thanks in advance,

 

Dr. E.

[mnn]

...

The only Plugin file in my ZIP archive is co.einsteinium.wikilinklib.plg.PluginMinecraftWiki.class

...

 

Do you have the class file in correct directory structure (

co/einsteinium/wikilinklib/plg/PluginMinecraftWiki.class

)?

[DrEinsteinium]

I think that is where my problem lies. I am loading from a zip file located in ./mods/WikiLink/ which means these classes are not loaded into the classpath at all. I don't know how to load them or even how to get the correct directory. All I am doing is mainly guesswork.

[mnn]

Probably the simplest solution would be to follow this answer.

[GotoLink]

With

final ClassLoader loader = WikiLink.class.getClassLoader();

You get net.minecraft.launchwrapper.LaunchClassLoader, thus reading Minecraft.jar.

You might want cpw.mods.fml.common.Loader instead.

[DrEinsteinium]

None of these solutions are working and I have no idea why.  I have essentially exhausted all of the tutorials I can find with no luck. Does anyone have any other ideas?

[mnn]

I think even using the other FML loader you still need to add zips/jars to the classpath. I'm curious why the urlclassloader isn't working (the snippet in the answer expects jar/zip file, not a directory - that can be otained e.g.

new File("dirPath").listFiles()

).

 

Do you have good path? Do you have properly organized insides of the jar/zip?