name.martingeisse.esdk.simulation.lwjgl.NativeLibraryHelper.java Source code

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Here is the source code for name.martingeisse.esdk.simulation.lwjgl.NativeLibraryHelper.java

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/**
 * Copyright (c) 2010 Martin Geisse
 *
 * This file is distributed under the terms of the MIT license.
 */

package name.martingeisse.esdk.simulation.lwjgl;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.lang.reflect.Field;

import name.martingeisse.esdk.simulation.OperatingSystemSelector;

import org.apache.commons.io.FileUtils;
import org.apache.log4j.Logger;

/**
 * Helper class that extracts LWJGL native libraries to a temporary folder
 * because Java is too stupid to load native libraries from inside a
 * JAR file.
 */
public final class NativeLibraryHelper {

    /**
     * the logger
     */
    private static Logger logger = Logger.getLogger(NativeLibraryHelper.class);

    /**
     * the resourcePath
     */
    private static String resourcePath;

    /**
     * the tempFolder
     */
    private static File tempFolder;

    /**
     * Extracts LWJGL libraries to a folder and 
     * @throws Exception on errors
     */
    public static void prepareNativeLibraries() throws Exception {

        // Unfortunately, Java is also too stupid to create a temp directory...
        tempFolder = File.createTempFile("miner-launcher-", "");
        deleteRecursively(tempFolder);
        tempFolder.mkdir();
        logger.debug("temp: " + tempFolder.getAbsolutePath());

        // detect which set of native libraries to load, then extract the files
        resourcePath = OperatingSystemSelector.getHostOs().getNativeLibraryPath();
        logger.debug("native library path: " + resourcePath);
        for (String fileName : OperatingSystemSelector.getHostOs().getNativeLibraryFileNames()) {
            extractFile(fileName);
        }

        // make Java use our libraries
        System.setProperty("java.library.path", tempFolder.getAbsolutePath());
        final Field fieldSysPath = ClassLoader.class.getDeclaredField("sys_paths");
        fieldSysPath.setAccessible(true);
        fieldSysPath.set(null, null);

    }

    /**
     * 
     */
    private static void deleteRecursively(File file) throws IOException {
        if (file.isDirectory()) {
            for (File sub : file.listFiles()) {
                deleteRecursively(sub);
            }
        }
        file.delete();
    }

    /**
     * 
     */
    private static void extractFile(String name) throws IOException {
        String fullResourceName = resourcePath + name;
        try (InputStream inputStream = NativeLibraryHelper.class.getClassLoader()
                .getResourceAsStream(fullResourceName)) {
            if (inputStream == null) {
                throw new RuntimeException("resource not found: " + fullResourceName);
            }
            FileUtils.copyInputStreamToFile(inputStream, new File(tempFolder, name));
        }
    }

}