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/*******************************************************************************
 * Copyright (c) 2010-present Sonatype, Inc.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Stuart McCulloch (Sonatype, Inc.) - initial API and implementation
 *******************************************************************************/
package org.eclipse.sisu.space;

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.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import java.util.jar.JarFile;
import java.util.jar.JarInputStream;
import java.util.jar.Manifest;

import org.eclipse.sisu.inject.DeferredClass;

/**
 * {@link ClassSpace} backed by a strongly-referenced {@link ClassLoader} and a {@link URL} class path.
 */
public class URLClassSpace
    implements ClassSpace
{
    // ----------------------------------------------------------------------
    // Static initialization
    // ----------------------------------------------------------------------

    static
    {
        ClassLoader systemLoader;
        String classPath;
        try
        {
            systemLoader = ClassLoader.getSystemClassLoader();
            classPath = System.getProperty( "java.class.path", "." );
        }
        catch ( final RuntimeException e )
        {
            systemLoader = null;
            classPath = null;
        }
        catch ( final LinkageError e )
        {
            systemLoader = null;
            classPath = null;
        }
        SYSTEM_LOADER = systemLoader;
        SYSTEM_CLASSPATH = classPath;
    }

    // ----------------------------------------------------------------------
    // Constants
    // ----------------------------------------------------------------------

    private static final String MANIFEST_ENTRY = "META-INF/MANIFEST.MF";

    private static final URL[] NO_URLS = {};

    private static final Enumeration NO_ENTRIES = Collections.enumeration( Collections. emptySet() );

    private static final String[] EMPTY_CLASSPATH = {};

    private static final ClassLoader SYSTEM_LOADER;

    private static final String SYSTEM_CLASSPATH;

    // ----------------------------------------------------------------------
    // Implementation fields
    // ----------------------------------------------------------------------

    private final ClassLoader loader;

    private final String pathDetails;

    private URL[] classPath;

    // ----------------------------------------------------------------------
    // Constructors
    // ----------------------------------------------------------------------

    /**
     * Creates a {@link ClassSpace} backed by a {@link ClassLoader} and its default class path.
     * 

* For {@link URLClassLoader}s this is their expanded Class-Path; otherwise it is empty. * * @param loader The class loader to use when getting/finding resources */ public URLClassSpace( final ClassLoader loader ) { this.loader = loader; pathDetails = null; // compute class path on demand } /** * Creates a {@link ClassSpace} backed by a {@link ClassLoader} with a restricted class path. * * @param loader The class loader to use when getting resources * @param path The class path to use when finding resources * @see #getResources(String) * @see #findEntries(String, String, boolean) */ public URLClassSpace( final ClassLoader loader, final URL[] path ) { this.loader = loader; pathDetails = Arrays.toString( path ); if ( null != path && path.length > 0 ) { classPath = expandClassPath( path ); } else { classPath = NO_URLS; } } // ---------------------------------------------------------------------- // Public methods // ---------------------------------------------------------------------- public final Class loadClass( final String name ) { try { return loader.loadClass( name ); } catch ( final Exception e ) { throw new TypeNotPresentException( name, e ); } catch ( final LinkageError e ) { throw new TypeNotPresentException( name, e ); } } public final DeferredClass deferLoadClass( final String name ) { return new NamedClass( this, name ); } public final URL getResource( final String name ) { return loader.getResource( name ); } public final Enumeration getResources( final String name ) { try { final Enumeration resources = loader.getResources( name ); return null != resources ? resources : NO_ENTRIES; // NOSONAR } catch ( final IOException e ) { return NO_ENTRIES; } } public final Enumeration findEntries( final String path, final String glob, final boolean recurse ) { // short-circuit finding resources with fixed names from default system class-path if ( null != SYSTEM_LOADER && loader == SYSTEM_LOADER && null == pathDetails // NOSONAR && !recurse && null != glob && glob.indexOf( '*' ) < 0 ) { return getResources( ResourceEnumeration.normalizeSearchPath( path ) + glob ); } return new ResourceEnumeration( path, glob, recurse, getClassPath() ); } public final URL[] getURLs() { return getClassPath().clone(); } @Override public final int hashCode() { return loader.hashCode(); // the loader is the primary key } @Override public final boolean equals( final Object rhs ) { if ( this == rhs ) { return true; } if ( rhs instanceof URLClassSpace ) { return loader.equals( ( (URLClassSpace) rhs ).loader ); } return false; } @Override public final String toString() { return null == pathDetails ? loader.toString() : loader + "(" + pathDetails + ")"; } // ---------------------------------------------------------------------- // Implementation methods // ---------------------------------------------------------------------- /** * Returns the associated {@link URL} class path; this can either be explicit or implicit. */ private synchronized URL[] getClassPath() { if ( null == classPath ) { for ( ClassLoader l = loader; l != null; l = l.getParent() ) { if ( l instanceof URLClassLoader ) { // pick first class loader with non-empty class path final URL[] path = ( (URLClassLoader) l ).getURLs(); if ( null != path && path.length > 0 ) { classPath = expandClassPath( path ); break; } } else if ( null != SYSTEM_LOADER && l == SYSTEM_LOADER ) // NOSONAR { classPath = expandClassPath( getSystemClassPath() ); break; } } if ( null == classPath ) { classPath = NO_URLS; // no detectable Class-Path } } return classPath; } /** * Returns the system {@link URL} class path. */ private static URL[] getSystemClassPath() { final String[] paths = SYSTEM_CLASSPATH.split( File.pathSeparator ); final URL[] urls = new URL[paths.length]; for ( int i = 0; i < paths.length; i++ ) { try { urls[i] = new File( paths[i] ).toURI().toURL(); } catch ( final MalformedURLException e ) { urls[i] = null; // ignore malformed class-path entry } } return urls; } /** * Expands the given {@link URL} class path to include Class-Path entries from local manifests. * * @param classPath The URL class path * @return Expanded URL class path */ private static URL[] expandClassPath( final URL[] classPath ) { final List searchPath = new ArrayList(); Collections.addAll( searchPath, classPath ); final List expandedPath = new ArrayList(); final Set visited = new HashSet(); // search path may grow, so use index not iterator for ( int i = 0; i < searchPath.size(); i++ ) { final URL url = normalizeEntry( searchPath.get( i ) ); if ( null == url || !visited.add( url.toString() ) ) { continue; // already processed } expandedPath.add( url ); final String[] classPathEntries; try { classPathEntries = getClassPathEntries( url ); } catch ( final IOException e ) { continue; // missing manifest } for ( final String entry : classPathEntries ) { try { searchPath.add( new URL( url, entry ) ); } catch ( final MalformedURLException e ) // NOPMD { // invalid Class-Path entry } } } return expandedPath.toArray( new URL[expandedPath.size()] ); } /** * Normalizes the given class path entry by removing any extraneous "jar:"..."!/" padding. * * @param path The URL to normalize * @return Normalized class path entry */ private static URL normalizeEntry( final URL url ) { if ( null != url && "jar".equals( url.getProtocol() ) ) { final String path = url.getPath(); if ( path.endsWith( "!/" ) ) { try { return new URL( path.substring( 0, path.length() - 2 ) ); } catch ( final MalformedURLException e ) { // this shouldn't happen, hence illegal state throw new IllegalStateException( e.toString() ); } } } return url; } /** * Looks for Class-Path entries in the given jar or directory; returns empty array if none are found. * * @param url The jar or directory to inspect * @return Array of Class-Path entries */ private static String[] getClassPathEntries( final URL url ) throws IOException { final Manifest manifest; if ( url.getPath().endsWith( "/" ) ) { final InputStream in = Streams.open( new URL( url, MANIFEST_ENTRY ) ); try { manifest = new Manifest( in ); } finally { in.close(); } } else if ( "file".equals( url.getProtocol() ) ) { final JarFile jf = new JarFile( FileEntryIterator.toFile( url ) ); try { manifest = jf.getManifest(); } finally { jf.close(); } } else { final JarInputStream jin = new JarInputStream( Streams.open( url ) ); try { manifest = jin.getManifest(); } finally { jin.close(); } } if ( null != manifest ) { final String classPath = manifest.getMainAttributes().getValue( "Class-Path" ); if ( null != classPath ) { return classPath.split( " " ); } } return EMPTY_CLASSPATH; } }