OSGiFileLocator.java

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package org.jruby.embed.osgi.utils;

import java.io.File;
import java.io.IOException;
import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLConnection;

import org.osgi.framework.Bundle;
import org.osgi.framework.BundleContext;
import org.osgi.framework.BundleException;
import org.osgi.framework.FrameworkUtil;

/**
 * Helper methods for the Ruby Runtime.
 * 
 * @author hmalphettes
 */
public class OSGiFileLocator {
    
    public static final String JRUBY_SYMBOLIC_NAME = "org.jruby.jruby";
        
    public static File getFileInBundle(String symbolicName, String path) throws IOException {
        Bundle bundle = getBundle(symbolicName);
        if (bundle == null) {
            throw new IOException("Unable to find the bundle " + symbolicName);
        }
        return getFileInBundle(bundle, path);
    }
    public static File getFileInBundle(Bundle bundle, String path) throws IOException {
        URL url = null;
        try {
            url = getFileURL(bundle.getEntry(path));
            return new File(url.getFile());
        } catch (NullPointerException ne) {
            throw new IOException("Unable to find the " + path + " folder in the bundle '" 
                    + bundle.getSymbolicName() + "'; is the org.jruby.jruby bundle unzipped? ");
        } catch (Exception e) {
            IOException exception = new IOException("Unable to find the " + path + 
                    " folder in the bundle '" + bundle.getSymbolicName() + "'");
            exception.initCause(e); // Should be safe since IOException(String) should call super(String).
            throw exception;
        }
    }

    /**
     * @param symbolicName
     * @return The bundle with this symbolic name
     */
    public static Bundle getBundle(String symbolicName) {
        BundleContext bc = FrameworkUtil.getBundle(OSGiFileLocator.class).getBundleContext();
        if (bc == null) {
            //if the bundle was not activatged then let's activate it.
            try {
                FrameworkUtil.getBundle(OSGiFileLocator.class).start();
            } catch (BundleException e) {
                throw new IllegalStateException("Could not start the bundle "
                    + FrameworkUtil.getBundle(OSGiFileLocator.class).getSymbolicName());
            }
            bc = FrameworkUtil.getBundle(OSGiFileLocator.class).getBundleContext();
            if (bc == null) {
                //this should never happen
                throw new IllegalStateException("The bundle "
                    + FrameworkUtil.getBundle(OSGiFileLocator.class).getSymbolicName()
                    + " is not activated.");
            }
        }
        for (Bundle b : FrameworkUtil.getBundle(OSGiFileLocator.class).getBundleContext().getBundles()) {
            if (b.getSymbolicName().equals(symbolicName)) {
                return b;
            }
        }
        return null;
    }
    
    //introspection on equinox to invoke the getLocalURL method on BundleURLConnection
    private static Method BUNDLE_URL_CONNECTION_getLocalURL = null;
    private static Method BUNDLE_URL_CONNECTION_getFileURL = null;
    /**
     * Only useful for equinox: on felix we get the file:// or jar:// url already.
     * Other OSGi implementations have not been tested
     * <p>
     * Get a URL to the bundle entry that uses a common protocol (i.e. file:
     * jar: or http: etc.).  
     * </p>
     * @return a URL to the bundle entry that uses a common protocol
     */
    public static URL getLocalURL(URL url) {
        if ("bundleresource".equals(url.getProtocol()) || "bundleentry".equals(url.getProtocol())) {
            try {
                URLConnection conn = url.openConnection();
                if (BUNDLE_URL_CONNECTION_getLocalURL == null && 
                        conn.getClass().getName().equals(
                                "org.eclipse.osgi.framework.internal.core.BundleURLConnection")) {
                    BUNDLE_URL_CONNECTION_getLocalURL = conn.getClass().getMethod("getLocalURL");
                    BUNDLE_URL_CONNECTION_getLocalURL.setAccessible(true);
                }
                if (BUNDLE_URL_CONNECTION_getLocalURL != null) {
                    return (URL)BUNDLE_URL_CONNECTION_getLocalURL.invoke(conn);
                }
            } catch (Throwable t) {
                t.printStackTrace();
            }
        }
        return url;
    }
    /**
     * Only useful for equinox: on felix we get the file:// url already.
     * Other OSGi implementations have not been tested
     * <p>
     * Get a URL to the content of the bundle entry that uses the file: protocol.
     * The content of the bundle entry may be downloaded or extracted to the local
     * file system in order to create a file: URL.
     * @return a URL to the content of the bundle entry that uses the file: protocol
     * </p>
     */
    public static URL getFileURL(URL url)
    {
        if ("bundleresource".equals(url.getProtocol()) || "bundleentry".equals(url.getProtocol()))
        {
            try
            {
                URLConnection conn = url.openConnection();
                if (BUNDLE_URL_CONNECTION_getFileURL == null && 
                        conn.getClass().getName().equals(
                                "org.eclipse.osgi.framework.internal.core.BundleURLConnection"))
                {
                    BUNDLE_URL_CONNECTION_getFileURL = conn.getClass().getMethod("getFileURL");
                    BUNDLE_URL_CONNECTION_getFileURL.setAccessible(true);
                }
                if (BUNDLE_URL_CONNECTION_getFileURL != null)
                {
                    return (URL)BUNDLE_URL_CONNECTION_getFileURL.invoke(conn);
                }
            }
            catch (Throwable t)
            {
                t.printStackTrace();
            }
        }
        return url;
    }
    
}