Brainstorm/Foundation Web Server/src/com/foundation/web/application/ServerClassLoader.java

package com.foundation.web.application;

import java.io.*;
import java.net.URL;
import java.net.URLConnection;
import java.net.URLStreamHandler;
import java.util.zip.*;
import java.util.jar.*;

/**
 * Used to load the view component builders only.
 */
public class ServerClassLoader extends ClassLoader {
	private File[] jars = null;
/**
 * ServerClassLoader constructor.
 * @param jars The java.io.File objects for each jar loadable.
 */
public ServerClassLoader(File[] jars) throws IOException {
	super();
	this.jars = jars;
	
	for(int index = 0; index < jars.length; index++) {
		File jar = jars[index];
		
		if(!jar.exists() || !jar.canRead()) {
			throw new IOException("Cannot find or access the jar: " + jar.getCanonicalPath());
		}//if//
		else if(!jar.getPath().toLowerCase().endsWith(".jar")) {
			throw new IOException("The passed file is not a jar: " + jar.getCanonicalPath());
		}//else if//
	}//for//
}//ServerClassLoader()//
/* (non-Javadoc)
 * @see java.lang.ClassLoader#findResource(java.lang.String)
 */
protected URL findResource(String name) {
	URL result = null;
	
	name = name.replace('\\', '/');
	
	while(name.charAt(0) == '/') {
		name = name.substring(1);
	}//while//
	
	for(int index = 0; result == null && index < jars.length; index++) {
		result = findResource(jars[index], name);
	}//for//
	
	return result;
}//findResource()//
/**
 * Finds the given class by searching the given file or directory.
 * @param file The file or directory to search.
 * @param classFileName The name of the class to find.
 */
private URL findResource(File file, String name) {
	URL result = null;
	
	if(file.exists()) {
		boolean cleanup = true;

		try {
			JarFile jar = new JarFile(file, false, JarFile.OPEN_READ);
			
			try {
				JarEntry entry = jar.getJarEntry(name);
				
				if(entry != null) {
					/*
					final JarFile jf = jar;
					final JarEntry je = entry;
					
					cleanup = false;
					result = new URL("", null, 0, name, new URLStreamHandler() {
						protected URLConnection openConnection(URL u) throws IOException {
							return new URLConnection(u) {
								public void connect() throws IOException {
								}//connect()//
								public InputStream getInputStream() throws IOException {
									return jf.getInputStream(je);
								}//getInputStream()//
								public void finalize() {
									try {jf.close();} catch(IOException e) {e.printStackTrace();}
								}//finalize()//
							};
						}//openConnection()//
					});
					*/

					final File jFile = file;
					final String jeName = name;
					
					result = new URL("", null, 0, name, new URLStreamHandler() {
						protected URLConnection openConnection(URL u) throws IOException {
							return new URLConnection(u) {
								public void connect() throws IOException {
								}//connect()//
								public InputStream getInputStream() throws IOException {
									return new InputStream() {
										JarFile _jar = new JarFile(jFile, false, JarFile.OPEN_READ);
										JarEntry _entry = _jar.getJarEntry(jeName);
										InputStream _in = _jar.getInputStream(_entry);
										
										public int read() throws IOException {
											return _in.read();
										}//read()//
										public int available() throws IOException {
											return _in.available();
										}//available()//
										public synchronized void mark(int readlimit) {
											_in.mark(readlimit);
										}//mark()//
										public boolean markSupported() {
											return _in.markSupported();
										}//markSupported()//
										public int read(byte[] b, int off, int len) throws IOException {
											return _in.read(b, off, len);
										}//read()//
										public int read(byte[] b) throws IOException {
											return _in.read(b);
										}//read()//
										public synchronized void reset() throws IOException {
											_in.reset();
										}//reset()//
										public long skip(long n) throws IOException {
											return _in.skip(n);
										}//skip()//
										public void close() throws IOException {
											try {_jar.close();} catch(IOException e) {e.printStackTrace();}
											super.close();
										}//close()//
									};
								}//getInputStream()//
							};
						}//openConnection()//
					});
				}//if//
			}//try//
			finally {
				if(cleanup && jar != null) {
					jar.close();
				}//if//
			}//finally//
		}//try//
		catch(IOException e) {
			throw new RuntimeException(e);
		}//catch//
	}//if//
	
	return result;
}//findResource()//
/* (non-Javadoc)
 * @see java.lang.ClassLoader#findClass(java.lang.String)
 */
protected Class findClass(String className) throws ClassNotFoundException {
	Class type = null;
	String classFileName = className.replace('.', '/') + ".class";
	
	//Debug.log("ServerClassLoader - Looking the for class: " + className);
	/*
	try {
		type = super.findClass(className);
	}//try//
	catch(ClassNotFoundException e) {
		//Ignore.//
	}//catch//
	*/
	for(int index = 0; type == null && index < jars.length; index++) {
		type = findClass(jars[index], className, classFileName);
	}//for//
	
	if(type == null) {
		throw new ClassNotFoundException("Couldn't find the class: " + className);
	}//if//
	
	return type;
}//findClass()//
/**
 * Finds the given class by searching the given file or directory.
 * @param file The file or directory to search.
 * @param classFileName The name of the class to find.
 */
private Class findClass(File file, String className, String classFileName) throws ClassNotFoundException {
	Class type = null;
	
	if(file.exists()) {
		byte[] bytes = null;

		try {
			JarFile jar = new JarFile(file, false, JarFile.OPEN_READ);
			
			try {
				JarEntry entry = jar.getJarEntry(classFileName);
				
				if(entry != null) {
					InputStream in = jar.getInputStream(entry);
					int approximateSize = in.available();
					int readCount = 0;
					//TODO: Can this be optimized?  Maybe smaller buffer.. maybe use a native buffer (nio)?
					byte[] buffer = new byte[1000];
					ByteArrayOutputStream bout = new ByteArrayOutputStream(approximateSize);
					
					//Read all the bytes into an in-memory buffer.//
					while(readCount != -1) {
						bout.write(buffer, 0, readCount);
						readCount = in.read(buffer);
					}//while//
					
					bytes = bout.toByteArray();
					in.close();
				}//if//
			}//try//
			finally {
				if(jar != null) {
					jar.close();
				}//if//
			}//finally//
			
			if(bytes != null) {
				type = defineClass(className, bytes, 0, bytes.length);
			}//if//
		}//try//
		catch(IOException e) {
			throw new RuntimeException(e);
		}//catch//
	}//if//
	
	return type;
}//findClass()//
}//ServerClassLoader//