com.qwazr.classloader.ClassLoaderManager Maven / Gradle / Ivy

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/**
 * Copyright 2016 Emmanuel Keller / QWAZR
 * 
 * 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.qwazr.classloader;

import com.qwazr.server.GenericServer;
import com.qwazr.utils.ClassLoaderUtils;
import com.qwazr.utils.IOUtils;

import java.io.Closeable;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.ArrayList;
import java.util.List;

public class ClassLoaderManager {

	public final File javaResourceDirectory;
	public final File javaClassesDirectory;
	public final File javaLibrariesDirectory;

	private final ClassLoader mainThreadClassLoader;
	private final Thread mainThread;

	private volatile ClassLoader classLoader;
	private volatile ClassFactory classFactory;

	public ClassLoaderManager(final File dataDirectory, final Thread mainThread) throws MalformedURLException {
		this.mainThread = mainThread == null ? Thread.currentThread() : mainThread;
		this.classFactory = ClassFactory.DefaultFactory.INSTANCE;
		this.mainThreadClassLoader = this.mainThread.getContextClassLoader();
		if (dataDirectory == null) {
			this.javaResourceDirectory = null;
			this.javaClassesDirectory = null;
			this.javaLibrariesDirectory = null;
		} else {
			this.javaResourceDirectory = new File(dataDirectory, "src/main/resources");
			this.javaClassesDirectory = new File(dataDirectory, "target/classes");
			this.javaLibrariesDirectory = new File(dataDirectory, "lib");
		}
		reload();
	}

	public ClassLoaderManager(final GenericServer.Builder builder, final Thread mainThread)
			throws MalformedURLException {
		this(builder == null ? null : builder.getConfiguration().dataDirectory, mainThread);
		if (builder != null)
			builder.contextAttribute(this);
	}

	public synchronized void reload() throws MalformedURLException {
		final ClassLoader oldClassLoader = classLoader;
		final List urlList = new ArrayList<>();
		if (javaResourceDirectory != null && javaResourceDirectory.exists())
			urlList.add(javaResourceDirectory.toURI().toURL());
		if (javaClassesDirectory != null && javaClassesDirectory.exists())
			urlList.add(javaClassesDirectory.toURI().toURL());
		if (javaLibrariesDirectory != null && javaLibrariesDirectory.exists())
			urlList.add(javaLibrariesDirectory.toURI().toURL());
		if (urlList.isEmpty()) {
			classLoader = mainThreadClassLoader;
			return;
		}
		final URL[] urls = urlList.toArray(new URL[urlList.size()]);
		final URLClassLoader newClassLoader = new URLClassLoader(urls, mainThreadClassLoader);
		mainThread.setContextClassLoader(newClassLoader);
		classLoader = newClassLoader;
		if (oldClassLoader != null && oldClassLoader != mainThreadClassLoader && oldClassLoader instanceof Closeable)
			IOUtils.close((Closeable) oldClassLoader);
	}

	final public void register(final ClassFactory classFactory) {
		this.classFactory = classFactory == null ? ClassFactory.DefaultFactory.INSTANCE : classFactory;
	}

	final public  T newInstance(final Class clazz) throws ReflectiveOperationException {
		return clazz == null ? null : classFactory.newInstance(clazz);
	}

	final public  T newInstance(final String className, final String[] classPrefixes)
			throws IOException, ReflectiveOperationException {
		return newInstance(ClassLoaderUtils.findClass(classLoader, className, classPrefixes));
	}

	final public  T newInstance(final String className) throws IOException, ReflectiveOperationException {
		return newInstance(ClassLoaderUtils.findClass(classLoader, className));
	}

	final public  Class findClass(final String className) throws ClassNotFoundException {
		return ClassLoaderUtils.findClass(classLoader, className);
	}

	final public InputStream getResourceAsStream(final String name) {
		return ClassLoaderUtils.getResourceAsStream(classLoader, name);
	}

	final public ClassLoader getClassLoader() {
		return classLoader;
	}

}