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/*  Copyright 1999 Vince Via [email protected]
    Licensed under the Apache License, Version 2.0 (the "License");
    you may not use this file except in compliance with the License.
    You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0
    Unless required by applicable law or agreed to in writing, software
    distributed under the License is distributed on an "AS IS" BASIS,
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    See the License for the specific language governing permissions and
    limitations under the License.
*/
package com.viaoa.util;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;

public class OAClassLoader extends ClassLoader {

	private final String className;
	private Class clazz;

	public OAClassLoader(String className) {
		this.className = className;
	}

	public Class loadClass(String className) throws ClassNotFoundException {
		if (!this.className.equals(className)) {
			return findSystemClass(className);
		}
		if (clazz != null) {
			return clazz;
		}

		String cn = className.replace('.', '/');
		InputStream is = ClassLoader.getSystemResourceAsStream(cn + ".class");
		if (is == null) {
			throw new ClassNotFoundException("could not load class as resource using OAClassLoader");
		}
		ByteArrayOutputStream baos = new ByteArrayOutputStream();
		for (;;) {
			int x;
			try {
				x = is.read();
			} catch (IOException e) {
				throw new ClassNotFoundException("IO exception while reading " + className + ".class", e);
			}
			if (x < 0) {
				break;
			}
			baos.write(x);
		}
		byte[] bs = baos.toByteArray();

		clazz = super.defineClass(className, bs, 0, bs.length);

		return clazz;
	}

	// test using Jar, or directory
	public static void main(String[] args) throws Exception {

		String cname = "com.viaoa.util.Test";

		OAClassLoader test = new OAClassLoader(cname);
		Class c = test.loadClass(cname);
		TestInterface t = (TestInterface) c.newInstance();
		t.test();
		System.out.println("Done");
	}

}