com.github.frtu.simple.infra.jdk.SunJdkHelper Maven / Gradle / Ivy

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Provide a set of classes for infrastructure and bootstrap that have very few dependencies that you can embedded easily into any application

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package com.github.frtu.simple.infra.jdk;

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

public class SunJdkHelper {
    private static final org.slf4j.Logger logger = org.slf4j.LoggerFactory.getLogger(SunJdkHelper.class);

    private static final String JAVA_LIBRARY_PATH = "java.library.path";
    // is ; or : depending on Windows or Linux
    private static final char SYSTEM_PROP_SEPARATOR = File.pathSeparatorChar;

    public static void appendToJavaLibraryPath(File libraryPath) {
        String currentLibPath = System.getProperty(JAVA_LIBRARY_PATH);
        logger.debug("Currently {}={}", JAVA_LIBRARY_PATH, currentLibPath);

        StringBuilder targetLibPath = new StringBuilder();
        targetLibPath.append(libraryPath.getAbsolutePath());
        if (currentLibPath != null && !"".equals(currentLibPath)) {
            targetLibPath.append(SYSTEM_PROP_SEPARATOR);
            targetLibPath.append(currentLibPath);
        }

        logger.info("Setting new {} to '{}'", JAVA_LIBRARY_PATH, targetLibPath);
        System.setProperty(JAVA_LIBRARY_PATH, targetLibPath.toString());

        resetJavaLibraryPath();
    }

    /**
     * Delete the cache of "java.library.path". This will force the classloader to recheck the modified value the next time we load
     * libraries.
     * 
     * Attention HACK : This is specific to Sun JVM and may not function on other JVM or other version of JVM... Currently checked
     * with JDK 1.5.x & 1.6.x
     */
    private static void resetJavaLibraryPath() {
        synchronized (Runtime.getRuntime()) {
            try {
                Field field = ClassLoader.class.getDeclaredField("usr_paths");
                field.setAccessible(true);
                field.set(null, null);

                field = ClassLoader.class.getDeclaredField("sys_paths");
                field.setAccessible(true);
                field.set(null, null);
            } catch (NoSuchFieldException e) {
                throw new RuntimeException(e);
            } catch (IllegalAccessException e) {
                throw new RuntimeException(e);
            }
        }
    }
}