plugins/org.eclipse.epp.installer.launcher/src/org/eclipse/epp/installer/launcher/SFXClassLoader.java

package org.eclipse.epp.installer.launcher;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.eclipse.epp.installer.archive.Archive;
import org.eclipse.epp.installer.archive.ArchiveEntry;


/**
 * <p>
 * Copyright (c) 2006, Instantiations, Inc.<br>
 * All Rights Reserved
 */
public class SFXClassLoader extends ClassLoader {
	private final static int BUFFER_SIZE = 4096;
	
	private Map libraryMap;
	private List classPath;

	public SFXClassLoader() {
		libraryMap = new HashMap();
		classPath = new ArrayList();
	}

	protected String findLibrary(String libname) {		
		String path = (String)libraryMap.get(libname);	
		if(path != null) {			
			return path;
		}
		else {			
			return super.findLibrary(libname);
		}
	}
	
	void addClassPath(Archive archive, String entry) {
		try {
			classPath.add(Archives.getSubArchive(archive, entry.split("!")));
		} catch (IOException e) {
			e.printStackTrace();
		} 
	}

	void mapLibrary(String libraryName, String path) {
		if(libraryMap.get(libraryName) != null) {
			System.err.println("warning: library already mapped, check INSTALLER.MF");
		}
		libraryMap.put(libraryName, path);
	}

	public InputStream getResourceAsStream(String name) {
		for(int i=0;i<classPath.size();i++) {
			Archive archive = (Archive) classPath.get(i);
			InputStream is = null;
			try {
				ArchiveEntry entry = archive.getEntry(name);
				if(entry != null) {
					is = archive.getInputStream(entry);
					return is;
				}
			} catch(IOException e) {
				e.printStackTrace();
			}
		}
		return super.getResourceAsStream(name);
	}

	protected Class findClass(String name) throws ClassNotFoundException {		
		for( int i = classPath.size() - 1; i >= 0; i-- ) {
			Archive archive = (Archive)classPath.get(i);
			String path = name.replace('.', '/') + ".class";
			InputStream is = null;
			try {
				ArchiveEntry entry = archive.getEntry(path);
				if(entry == null) continue;
				is = archive.getInputStream(entry);
				ByteArrayOutputStream bos = new ByteArrayOutputStream();
				byte[] buf = new byte[BUFFER_SIZE];
				int n;
				while ((n = is.read(buf)) != -1) {
					bos.write(buf, 0, n);
				}
				byte[] clazz = bos.toByteArray(); 
				return defineClass(name, clazz, 0, clazz.length); 
			} catch(IOException e) {
				e.printStackTrace();
			}
		}
		return super.findClass(name);
	}

	protected synchronized Class loadClass(String name, boolean resolve) throws ClassNotFoundException {
        // First, check if the class has already been loaded
        Class c = findLoadedClass(name);

        // if not loaded, search the local (child) resources
        if (c == null) {
           try {
              c = findClass(name);
           } catch(ClassNotFoundException cnfe) {
              // ignore
           }
        }

        // delegate to parent
        if (c == null) {
           if (getParent() != null) {
              c = getParent().loadClass(name);
           } else {
              c = getSystemClassLoader().loadClass(name);
           }
        }

        // Resolve the class, if required
        if (resolve) {
           resolveClass(c);
        }

        return c;
	}
}