ClassLoaderUtil.java

/**
 * CopyRight by Chinamobile
 * 
 * ClassLoaderUtil.java
 */
package com.chinamobile.bcbsp.util;

import java.io.File;
import java.io.PrintStream;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.List;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import sun.misc.Launcher;

/**
 * ClassLoaderUtil
 * 
 * Offer static methods to add file or path to the system's classpath.
 * 
 * @author 
 * @version 
 */
public class ClassLoaderUtil {
    private static Field classes;
    private static final Log LOG = LogFactory.getLog(ClassLoaderUtil.class);
    private static Method addURL;
    static {
        try {
            classes = ClassLoader.class.getDeclaredField("classes");
            addURL = URLClassLoader.class.getDeclaredMethod("addURL",
                    new Class[] { URL.class });
        } catch (Exception e) {
            e.printStackTrace();
        }
        classes.setAccessible(true);
        addURL.setAccessible(true);
    }

    private static URLClassLoader system = (URLClassLoader) getSystemClassLoader();

    private static URLClassLoader ext = (URLClassLoader) getExtClassLoader();

    public static ClassLoader getSystemClassLoader() {
        return ClassLoader.getSystemClassLoader();
    }

    public static ClassLoader getExtClassLoader() {
        return getSystemClassLoader().getParent();
    }

    @SuppressWarnings("unchecked")
    public static List getClassesLoadedBySystemClassLoader() {
        return getClassesLoadedByClassLoader(getSystemClassLoader());
    }

    @SuppressWarnings("unchecked")
    public static List getClassesLoadedByExtClassLoader() {
        return getClassesLoadedByClassLoader(getExtClassLoader());
    }

    @SuppressWarnings("unchecked")
    public static List getClassesLoadedByClassLoader(ClassLoader cl) {
        try {
            return (List) classes.get(cl);
        } catch (Exception e) {
            LOG.error("[getClassesLoadedByClassLoader]", e);
        }
        return null;
    }

    public static URL[] getBootstrapURLs() {
        return Launcher.getBootstrapClassPath().getURLs();
    }

    public static URL[] getSystemURLs() {
        return system.getURLs();
    }

    public static URL[] getExtURLs() {
        return ext.getURLs();
    }

    private static void list(PrintStream ps, URL[] classPath) {
        for (int i = 0; i < classPath.length; i++) {
            ps.println(classPath[i]);
        }
    }

    public static void listBootstrapClassPath() {
        listBootstrapClassPath(System.out);
    }

    public static void listBootstrapClassPath(PrintStream ps) {
        ps.println("BootstrapClassPath:");
        list(ps, getBootstrapClassPath());
    }

    public static void listSystemClassPath() {
        listSystemClassPath(System.out);
    }

    public static void listSystemClassPath(PrintStream ps) {
        ps.println("SystemClassPath:");
        list(ps, getSystemClassPath());
    }

    public static void listExtClassPath() {
        listExtClassPath(System.out);
    }

    public static void listExtClassPath(PrintStream ps) {
        ps.println("ExtClassPath:");
        list(ps, getExtClassPath());
    }

    public static URL[] getBootstrapClassPath() {
        return getBootstrapURLs();
    }

    public static URL[] getSystemClassPath() {
        return getSystemURLs();
    }

    public static URL[] getExtClassPath() {
        return getExtURLs();
    }

    public static void addURL2SystemClassLoader(URL url) {
        try {
            addURL.invoke(system, new Object[] { url });
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public static void addURL2ExtClassLoader(URL url) {
        try {
            addURL.invoke(ext, new Object[] { url });
        } catch (Exception e) {
            LOG.error("[addURL2ExtClassLoader]", e);
        }
    }

    public static void addClassPath(String path) {
        addClassPath(new File(path));
    }

    public static void addExtClassPath(String path) {
        addExtClassPath(new File(path));
    }

    public static void addClassPath(File dirOrJar) {
        try {
            addURL2SystemClassLoader(dirOrJar.toURI().toURL());
        } catch (MalformedURLException e) {
            LOG.error("[addClassPath]", e);
        }
    }

    public static void addExtClassPath(File dirOrJar) {
        try {
            addURL2ExtClassLoader(dirOrJar.toURI().toURL());
        } catch (MalformedURLException e) {
            LOG.error("[addExtClassPath]", e);
        }
    }
}