https://openjdk.java.net/ 
/*
 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.net;

import java.io.Closeable;
import java.io.File;
import java.io.FilePermission;
import java.io.IOException;
import java.io.InputStream;
import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.CodeSigner;
import java.security.CodeSource;
import java.security.Permission;
import java.security.PermissionCollection;
import java.security.PrivilegedAction;
import java.security.PrivilegedExceptionAction;
import java.security.SecureClassLoader;
import java.util.Enumeration;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.Objects;
import java.util.Set;
import java.util.WeakHashMap;
import java.util.jar.Attributes;
import java.util.jar.Attributes.Name;
import java.util.jar.JarFile;
import java.util.jar.Manifest;

import jdk.internal.loader.Resource;
import jdk.internal.loader.URLClassPath;
import jdk.internal.access.JavaNetURLClassLoaderAccess;
import jdk.internal.access.SharedSecrets;
import jdk.internal.perf.PerfCounter;
import sun.net.www.ParseUtil;
import sun.security.util.SecurityConstants;


This class loader is used to load classes and resources from a search path of URLs referring to both JAR files and directories. Any jar: scheme URL (see JarURLConnection) is assumed to refer to a JAR file. Any file: scheme URL that ends with a '/' is assumed to refer to a directory. Otherwise, the URL is assumed to refer to a JAR file which will be opened as needed. 

This class loader supports the loading of classes and resources from the
contents of a multi-release
JAR file that is referred to by a given URL.


The AccessControlContext of the thread that created the instance of
URLClassLoader will be used when subsequently loading classes and
resources.


The classes that are loaded are by default granted permission only to
access the URLs specified when the URLClassLoader was created.

Author: David Connelly
Since:  1.2
/**
 * This class loader is used to load classes and resources from a search
 * path of URLs referring to both JAR files and directories. Any {@code jar:}
 * scheme URL (see {@link java.net.JarURLConnection}) is assumed to refer to a
 * JAR file.  Any {@code file:} scheme URL that ends with a '/' is assumed to
 * refer to a directory. Otherwise, the URL is assumed to refer to a JAR file
 * which will be opened as needed.
 * <p>
 * This class loader supports the loading of classes and resources from the
 * contents of a <a href="../util/jar/JarFile.html#multirelease">multi-release</a>
 * JAR file that is referred to by a given URL.
 * <p>
 * The AccessControlContext of the thread that created the instance of
 * URLClassLoader will be used when subsequently loading classes and
 * resources.
 * <p>
 * The classes that are loaded are by default granted permission only to
 * access the URLs specified when the URLClassLoader was created.
 *
 * @author  David Connelly
 * @since   1.2
 */
public class URLClassLoader extends SecureClassLoader implements Closeable {
    /* The search path for classes and resources */
    private final URLClassPath ucp;

    /* The context to be used when loading classes and resources */
    private final AccessControlContext acc;

    
Constructs a new URLClassLoader for the given URLs. The URLs will be searched in the order specified for classes and resources after first searching in the specified parent class loader. Any jar: scheme URL is assumed to refer to a JAR file. Any file: scheme URL that ends with a '/' is assumed to refer to a directory. Otherwise, the URL is assumed to refer to a JAR file which will be downloaded and opened as needed. 
If there is a security manager, this method first calls the security manager's checkCreateClassLoader method to ensure creation of a class loader is allowed. 
Params:
  • urls – the URLs from which to load classes and resources
  • parent – the parent class loader for delegation
Throws:
  • SecurityException –  if a security manager exists and its checkCreateClassLoader method doesn't allow creation of a class loader.
  • NullPointerException – if urls or any of its elements is null.
See Also:
/**
     * Constructs a new URLClassLoader for the given URLs. The URLs will be
     * searched in the order specified for classes and resources after first
     * searching in the specified parent class loader.  Any {@code jar:}
     * scheme URL is assumed to refer to a JAR file.  Any {@code file:} scheme
     * URL that ends with a '/' is assumed to refer to a directory.  Otherwise,
     * the URL is assumed to refer to a JAR file which will be downloaded and
     * opened as needed.
     *
     * <p>If there is a security manager, this method first
     * calls the security manager's {@code checkCreateClassLoader} method
     * to ensure creation of a class loader is allowed.
     *
     * @param urls the URLs from which to load classes and resources
     * @param parent the parent class loader for delegation
     * @exception  SecurityException  if a security manager exists and its
     *             {@code checkCreateClassLoader} method doesn't allow
     *             creation of a class loader.
     * @exception  NullPointerException if {@code urls} or any of its
     *             elements is {@code null}.
     * @see SecurityManager#checkCreateClassLoader
     */
    public URLClassLoader(URL[] urls, ClassLoader parent) {
        super(parent);
        this.acc = AccessController.getContext();
        this.ucp = new URLClassPath(urls, acc);
    }

    URLClassLoader(String name, URL[] urls, ClassLoader parent,
                   AccessControlContext acc) {
        super(name, parent);
        this.acc = acc;
        this.ucp = new URLClassPath(urls, acc);
    }

    
Constructs a new URLClassLoader for the specified URLs using the default delegation parent ClassLoader. The URLs will be searched in the order specified for classes and resources after first searching in the parent class loader. Any URL that ends with a '/' is assumed to refer to a directory. Otherwise, the URL is assumed to refer to a JAR file which will be downloaded and opened as needed. 
If there is a security manager, this method first calls the security manager's checkCreateClassLoader method to ensure creation of a class loader is allowed. 
Params:
  • urls – the URLs from which to load classes and resources
Throws:
  • SecurityException –  if a security manager exists and its checkCreateClassLoader method doesn't allow creation of a class loader.
  • NullPointerException – if urls or any of its elements is null.
See Also:
/**
     * Constructs a new URLClassLoader for the specified URLs using the
     * default delegation parent {@code ClassLoader}. The URLs will
     * be searched in the order specified for classes and resources after
     * first searching in the parent class loader. Any URL that ends with
     * a '/' is assumed to refer to a directory. Otherwise, the URL is
     * assumed to refer to a JAR file which will be downloaded and opened
     * as needed.
     *
     * <p>If there is a security manager, this method first
     * calls the security manager's {@code checkCreateClassLoader} method
     * to ensure creation of a class loader is allowed.
     *
     * @param urls the URLs from which to load classes and resources
     *
     * @exception  SecurityException  if a security manager exists and its
     *             {@code checkCreateClassLoader} method doesn't allow
     *             creation of a class loader.
     * @exception  NullPointerException if {@code urls} or any of its
     *             elements is {@code null}.
     * @see SecurityManager#checkCreateClassLoader
     */
    public URLClassLoader(URL[] urls) {
        super();
        this.acc = AccessController.getContext();
        this.ucp = new URLClassPath(urls, acc);
    }

    URLClassLoader(URL[] urls, AccessControlContext acc) {
        super();
        this.acc = acc;
        this.ucp = new URLClassPath(urls, acc);
    }

    
Constructs a new URLClassLoader for the specified URLs, parent
class loader, and URLStreamHandlerFactory. The parent argument
will be used as the parent class loader for delegation. The
factory argument will be used as the stream handler factory to
obtain protocol handlers when creating new jar URLs.

If there is a security manager, this method first calls the security manager's checkCreateClassLoader method to ensure creation of a class loader is allowed. 
Params:
  • urls – the URLs from which to load classes and resources
  • parent – the parent class loader for delegation
  • factory – the URLStreamHandlerFactory to use when creating URLs
Throws:
  • SecurityException –  if a security manager exists and its checkCreateClassLoader method doesn't allow creation of a class loader.
  • NullPointerException – if urls or any of its elements is null.
See Also:
/**
     * Constructs a new URLClassLoader for the specified URLs, parent
     * class loader, and URLStreamHandlerFactory. The parent argument
     * will be used as the parent class loader for delegation. The
     * factory argument will be used as the stream handler factory to
     * obtain protocol handlers when creating new jar URLs.
     *
     * <p>If there is a security manager, this method first
     * calls the security manager's {@code checkCreateClassLoader} method
     * to ensure creation of a class loader is allowed.
     *
     * @param urls the URLs from which to load classes and resources
     * @param parent the parent class loader for delegation
     * @param factory the URLStreamHandlerFactory to use when creating URLs
     *
     * @exception  SecurityException  if a security manager exists and its
     *             {@code checkCreateClassLoader} method doesn't allow
     *             creation of a class loader.
     * @exception  NullPointerException if {@code urls} or any of its
     *             elements is {@code null}.
     * @see SecurityManager#checkCreateClassLoader
     */
    public URLClassLoader(URL[] urls, ClassLoader parent,
                          URLStreamHandlerFactory factory) {
        super(parent);
        this.acc = AccessController.getContext();
        this.ucp = new URLClassPath(urls, factory, acc);
    }


    
Constructs a new named URLClassLoader for the specified URLs. The URLs will be searched in the order specified for classes and resources after first searching in the specified parent class loader. Any URL that ends with a '/' is assumed to refer to a directory. Otherwise, the URL is assumed to refer to a JAR file which will be downloaded and opened as needed. 
Params:
  • name – class loader name; or null if not named
  • urls – the URLs from which to load classes and resources
  • parent – the parent class loader for delegation
Throws:
Since:9
@specJPMS
/**
     * Constructs a new named {@code URLClassLoader} for the specified URLs.
     * The URLs will be searched in the order specified for classes
     * and resources after first searching in the specified parent class loader.
     * Any URL that ends with a '/' is assumed to refer to a directory.
     * Otherwise, the URL is assumed to refer to a JAR file which will be
     * downloaded and opened as needed.
     *
     * @param  name class loader name; or {@code null} if not named
     * @param  urls the URLs from which to load classes and resources
     * @param  parent the parent class loader for delegation
     *
     * @throws IllegalArgumentException if the given name is empty.
     * @throws NullPointerException if {@code urls} or any of its
     *         elements is {@code null}.
     *
     * @throws SecurityException if a security manager exists and its
     *         {@link SecurityManager#checkCreateClassLoader()} method doesn't
     *         allow creation of a class loader.
     *
     * @since 9
     * @spec JPMS
     */
    public URLClassLoader(String name,
                          URL[] urls,
                          ClassLoader parent) {
        super(name, parent);
        this.acc = AccessController.getContext();
        this.ucp = new URLClassPath(urls, acc);
    }

    
Constructs a new named URLClassLoader for the specified URLs, parent class loader, and URLStreamHandlerFactory. The parent argument will be used as the parent class loader for delegation. The factory argument will be used as the stream handler factory to obtain protocol handlers when creating new jar URLs. 
Params:
  • name – class loader name; or null if not named
  • urls – the URLs from which to load classes and resources
  • parent – the parent class loader for delegation
  • factory – the URLStreamHandlerFactory to use when creating URLs
Throws:
Since:9
@specJPMS
/**
     * Constructs a new named {@code URLClassLoader} for the specified URLs,
     * parent class loader, and URLStreamHandlerFactory.
     * The parent argument will be used as the parent class loader for delegation.
     * The factory argument will be used as the stream handler factory to
     * obtain protocol handlers when creating new jar URLs.
     *
     * @param  name class loader name; or {@code null} if not named
     * @param  urls the URLs from which to load classes and resources
     * @param  parent the parent class loader for delegation
     * @param  factory the URLStreamHandlerFactory to use when creating URLs
     *
     * @throws IllegalArgumentException if the given name is empty.
     * @throws NullPointerException if {@code urls} or any of its
     *         elements is {@code null}.
     *
     * @throws SecurityException if a security manager exists and its
     *         {@code checkCreateClassLoader} method doesn't allow
     *         creation of a class loader.
     *
     * @since 9
     * @spec JPMS
     */
    public URLClassLoader(String name, URL[] urls, ClassLoader parent,
                          URLStreamHandlerFactory factory) {
        super(name, parent);
        this.acc = AccessController.getContext();
        this.ucp = new URLClassPath(urls, factory, acc);
    }

    /* A map (used as a set) to keep track of closeable local resources
     * (either JarFiles or FileInputStreams). We don't care about
     * Http resources since they don't need to be closed.
     *
     * If the resource is coming from a jar file
     * we keep a (weak) reference to the JarFile object which can
     * be closed if URLClassLoader.close() called. Due to jar file
     * caching there will typically be only one JarFile object
     * per underlying jar file.
     *
     * For file resources, which is probably a less common situation
     * we have to keep a weak reference to each stream.
     */

    private WeakHashMap<Closeable,Void>
        closeables = new WeakHashMap<>();

    
Returns an input stream for reading the specified resource.
If this loader is closed, then any resources opened by this method
will be closed.

 The search order is described in the documentation for ClassLoader.getResource(String). 


Params:
  • name – 
        The resource name
Throws:
Returns: An input stream for reading the resource, or null if the resource could not be found
Since: 1.7
/**
     * Returns an input stream for reading the specified resource.
     * If this loader is closed, then any resources opened by this method
     * will be closed.
     *
     * <p> The search order is described in the documentation for {@link
     * #getResource(String)}.  </p>
     *
     * @param  name
     *         The resource name
     *
     * @return  An input stream for reading the resource, or {@code null}
     *          if the resource could not be found
     *
     * @throws  NullPointerException If {@code name} is {@code null}
     *
     * @since  1.7
     */
    public InputStream getResourceAsStream(String name) {
        Objects.requireNonNull(name);
        URL url = getResource(name);
        try {
            if (url == null) {
                return null;
            }
            URLConnection urlc = url.openConnection();
            InputStream is = urlc.getInputStream();
            if (urlc instanceof JarURLConnection) {
                JarURLConnection juc = (JarURLConnection)urlc;
                JarFile jar = juc.getJarFile();
                synchronized (closeables) {
                    if (!closeables.containsKey(jar)) {
                        closeables.put(jar, null);
                    }
                }
            } else if (urlc instanceof sun.net.www.protocol.file.FileURLConnection) {
                synchronized (closeables) {
                    closeables.put(is, null);
                }
            }
            return is;
        } catch (IOException e) {
            return null;
        }
    }

   
Closes this URLClassLoader, so that it can no longer be used to load
new classes or resources that are defined by this loader.
Classes and resources defined by any of this loader's parents in the
delegation hierarchy are still accessible. Also, any classes or resources
that are already loaded, are still accessible.

 In the case of jar: and file: URLs, it also closes any files that were opened by it. If another thread is loading a class when the close method is invoked, then the result of that load is undefined. 
 The method makes a best effort attempt to close all opened files, by catching IOExceptions internally. Unchecked exceptions and errors are not caught. Calling close on an already closed loader has no effect. 
Throws:
  • IOException – if closing any file opened by this class loader
resulted in an IOException. Any such exceptions are caught internally.
If only one is caught, then it is re-thrown. If more than one exception
is caught, then the second and following exceptions are added
as suppressed exceptions of the first one caught, which is then re-thrown.
  • SecurityException – if a security manager is set, and it denies RuntimePermission("closeClassLoader")
Since:1.7
/**
    * Closes this URLClassLoader, so that it can no longer be used to load
    * new classes or resources that are defined by this loader.
    * Classes and resources defined by any of this loader's parents in the
    * delegation hierarchy are still accessible. Also, any classes or resources
    * that are already loaded, are still accessible.
    * <p>
    * In the case of jar: and file: URLs, it also closes any files
    * that were opened by it. If another thread is loading a
    * class when the {@code close} method is invoked, then the result of
    * that load is undefined.
    * <p>
    * The method makes a best effort attempt to close all opened files,
    * by catching {@link IOException}s internally. Unchecked exceptions
    * and errors are not caught. Calling close on an already closed
    * loader has no effect.
    *
    * @exception IOException if closing any file opened by this class loader
    * resulted in an IOException. Any such exceptions are caught internally.
    * If only one is caught, then it is re-thrown. If more than one exception
    * is caught, then the second and following exceptions are added
    * as suppressed exceptions of the first one caught, which is then re-thrown.
    *
    * @exception SecurityException if a security manager is set, and it denies
    *   {@link RuntimePermission}{@code ("closeClassLoader")}
    *
    * @since 1.7
    */
    public void close() throws IOException {
        SecurityManager security = System.getSecurityManager();
        if (security != null) {
            security.checkPermission(new RuntimePermission("closeClassLoader"));
        }
        List<IOException> errors = ucp.closeLoaders();

        // now close any remaining streams.

        synchronized (closeables) {
            Set<Closeable> keys = closeables.keySet();
            for (Closeable c : keys) {
                try {
                    c.close();
                } catch (IOException ioex) {
                    errors.add(ioex);
                }
            }
            closeables.clear();
        }

        if (errors.isEmpty()) {
            return;
        }

        IOException firstex = errors.remove(0);

        // Suppress any remaining exceptions

        for (IOException error: errors) {
            firstex.addSuppressed(error);
        }
        throw firstex;
    }

    
Appends the specified URL to the list of URLs to search for
classes and resources.

 If the URL specified is null or is already in the list of URLs, or if this loader is closed, then invoking this method has no effect. 
Params:
  • url – the URL to be added to the search path of URLs
/**
     * Appends the specified URL to the list of URLs to search for
     * classes and resources.
     * <p>
     * If the URL specified is {@code null} or is already in the
     * list of URLs, or if this loader is closed, then invoking this
     * method has no effect.
     *
     * @param url the URL to be added to the search path of URLs
     */
    protected void addURL(URL url) {
        ucp.addURL(url);
    }

    
Returns the search path of URLs for loading classes and resources.
This includes the original list of URLs specified to the constructor,
along with any URLs subsequently appended by the addURL() method.

Returns:the search path of URLs for loading classes and resources.
/**
     * Returns the search path of URLs for loading classes and resources.
     * This includes the original list of URLs specified to the constructor,
     * along with any URLs subsequently appended by the addURL() method.
     * @return the search path of URLs for loading classes and resources.
     */
    public URL[] getURLs() {
        return ucp.getURLs();
    }

    
Finds and loads the class with the specified name from the URL search
path. Any URLs referring to JAR files are loaded and opened as needed
until the class is found.

Params:
  • name – the name of the class
Throws:
Returns:the resulting class
/**
     * Finds and loads the class with the specified name from the URL search
     * path. Any URLs referring to JAR files are loaded and opened as needed
     * until the class is found.
     *
     * @param name the name of the class
     * @return the resulting class
     * @exception ClassNotFoundException if the class could not be found,
     *            or if the loader is closed.
     * @exception NullPointerException if {@code name} is {@code null}.
     */
    protected Class<?> findClass(final String name)
        throws ClassNotFoundException
    {
        final Class<?> result;
        try {
            result = AccessController.doPrivileged(
                new PrivilegedExceptionAction<>() {
                    public Class<?> run() throws ClassNotFoundException {
                        String path = name.replace('.', '/').concat(".class");
                        Resource res = ucp.getResource(path, false);
                        if (res != null) {
                            try {
                                return defineClass(name, res);
                            } catch (IOException e) {
                                throw new ClassNotFoundException(name, e);
                            }
                        } else {
                            return null;
                        }
                    }
                }, acc);
        } catch (java.security.PrivilegedActionException pae) {
            throw (ClassNotFoundException) pae.getException();
        }
        if (result == null) {
            throw new ClassNotFoundException(name);
        }
        return result;
    }

    /*
     * Retrieve the package using the specified package name.
     * If non-null, verify the package using the specified code
     * source and manifest.
     */
    private Package getAndVerifyPackage(String pkgname,
                                        Manifest man, URL url) {
        Package pkg = getDefinedPackage(pkgname);
        if (pkg != null) {
            // Package found, so check package sealing.
            if (pkg.isSealed()) {
                // Verify that code source URL is the same.
                if (!pkg.isSealed(url)) {
                    throw new SecurityException(
                        "sealing violation: package " + pkgname + " is sealed");
                }
            } else {
                // Make sure we are not attempting to seal the package
                // at this code source URL.
                if ((man != null) && isSealed(pkgname, man)) {
                    throw new SecurityException(
                        "sealing violation: can't seal package " + pkgname +
                        ": already loaded");
                }
            }
        }
        return pkg;
    }

    /*
     * Defines a Class using the class bytes obtained from the specified
     * Resource. The resulting Class must be resolved before it can be
     * used.
     */
    private Class<?> defineClass(String name, Resource res) throws IOException {
        long t0 = System.nanoTime();
        int i = name.lastIndexOf('.');
        URL url = res.getCodeSourceURL();
        if (i != -1) {
            String pkgname = name.substring(0, i);
            // Check if package already loaded.
            Manifest man = res.getManifest();
            if (getAndVerifyPackage(pkgname, man, url) == null) {
                try {
                    if (man != null) {
                        definePackage(pkgname, man, url);
                    } else {
                        definePackage(pkgname, null, null, null, null, null, null, null);
                    }
                } catch (IllegalArgumentException iae) {
                    // parallel-capable class loaders: re-verify in case of a
                    // race condition
                    if (getAndVerifyPackage(pkgname, man, url) == null) {
                        // Should never happen
                        throw new AssertionError("Cannot find package " +
                                                 pkgname);
                    }
                }
            }
        }
        // Now read the class bytes and define the class
        java.nio.ByteBuffer bb = res.getByteBuffer();
        if (bb != null) {
            // Use (direct) ByteBuffer:
            CodeSigner[] signers = res.getCodeSigners();
            CodeSource cs = new CodeSource(url, signers);
            PerfCounter.getReadClassBytesTime().addElapsedTimeFrom(t0);
            return defineClass(name, bb, cs);
        } else {
            byte[] b = res.getBytes();
            // must read certificates AFTER reading bytes.
            CodeSigner[] signers = res.getCodeSigners();
            CodeSource cs = new CodeSource(url, signers);
            PerfCounter.getReadClassBytesTime().addElapsedTimeFrom(t0);
            return defineClass(name, b, 0, b.length, cs);
        }
    }

    
Defines a new package by name in this URLClassLoader. The attributes contained in the specified Manifest will be used to obtain package version and sealing information. For sealed packages, the additional URL specifies the code source URL from which the package was loaded. 
Params:
  • name –  the package name
  • man –  the Manifest containing package version and sealing information
  • url –   the code source url for the package, or null if none
Throws:
Returns: the newly defined Package object
@revised9
@specJPMS
/**
     * Defines a new package by name in this {@code URLClassLoader}.
     * The attributes contained in the specified {@code Manifest}
     * will be used to obtain package version and sealing information.
     * For sealed packages, the additional URL specifies the code source URL
     * from which the package was loaded.
     *
     * @param name  the package name
     * @param man   the {@code Manifest} containing package version and sealing
     *              information
     * @param url   the code source url for the package, or null if none
     * @throws      IllegalArgumentException if the package name is
     *              already defined by this class loader
     * @return      the newly defined {@code Package} object
     *
     * @revised 9
     * @spec JPMS
     */
    protected Package definePackage(String name, Manifest man, URL url) {
        String specTitle = null, specVersion = null, specVendor = null;
        String implTitle = null, implVersion = null, implVendor = null;
        String sealed = null;
        URL sealBase = null;

        Attributes attr = SharedSecrets.javaUtilJarAccess()
                .getTrustedAttributes(man, name.replace('.', '/').concat("/"));
        if (attr != null) {
            specTitle   = attr.getValue(Name.SPECIFICATION_TITLE);
            specVersion = attr.getValue(Name.SPECIFICATION_VERSION);
            specVendor  = attr.getValue(Name.SPECIFICATION_VENDOR);
            implTitle   = attr.getValue(Name.IMPLEMENTATION_TITLE);
            implVersion = attr.getValue(Name.IMPLEMENTATION_VERSION);
            implVendor  = attr.getValue(Name.IMPLEMENTATION_VENDOR);
            sealed      = attr.getValue(Name.SEALED);
        }
        attr = man.getMainAttributes();
        if (attr != null) {
            if (specTitle == null) {
                specTitle = attr.getValue(Name.SPECIFICATION_TITLE);
            }
            if (specVersion == null) {
                specVersion = attr.getValue(Name.SPECIFICATION_VERSION);
            }
            if (specVendor == null) {
                specVendor = attr.getValue(Name.SPECIFICATION_VENDOR);
            }
            if (implTitle == null) {
                implTitle = attr.getValue(Name.IMPLEMENTATION_TITLE);
            }
            if (implVersion == null) {
                implVersion = attr.getValue(Name.IMPLEMENTATION_VERSION);
            }
            if (implVendor == null) {
                implVendor = attr.getValue(Name.IMPLEMENTATION_VENDOR);
            }
            if (sealed == null) {
                sealed = attr.getValue(Name.SEALED);
            }
        }
        if ("true".equalsIgnoreCase(sealed)) {
            sealBase = url;
        }
        return definePackage(name, specTitle, specVersion, specVendor,
                             implTitle, implVersion, implVendor, sealBase);
    }

    /*
     * Returns true if the specified package name is sealed according to the
     * given manifest.
     *
     * @throws SecurityException if the package name is untrusted in the manifest
     */
    private boolean isSealed(String name, Manifest man) {
        Attributes attr = SharedSecrets.javaUtilJarAccess()
                .getTrustedAttributes(man, name.replace('.', '/').concat("/"));
        String sealed = null;
        if (attr != null) {
            sealed = attr.getValue(Name.SEALED);
        }
        if (sealed == null) {
            if ((attr = man.getMainAttributes()) != null) {
                sealed = attr.getValue(Name.SEALED);
            }
        }
        return "true".equalsIgnoreCase(sealed);
    }

    
Finds the resource with the specified name on the URL search path.

Params:
  • name – the name of the resource
Returns:a URL for the resource, or null if the resource could not be found, or if the loader is closed.
/**
     * Finds the resource with the specified name on the URL search path.
     *
     * @param name the name of the resource
     * @return a {@code URL} for the resource, or {@code null}
     * if the resource could not be found, or if the loader is closed.
     */
    public URL findResource(final String name) {
        /*
         * The same restriction to finding classes applies to resources
         */
        URL url = AccessController.doPrivileged(
            new PrivilegedAction<>() {
                public URL run() {
                    return ucp.findResource(name, true);
                }
            }, acc);

        return url != null ? URLClassPath.checkURL(url) : null;
    }

    
Returns an Enumeration of URLs representing all of the resources
on the URL search path having the specified name.

Params:
  • name – the resource name
Throws:
Returns:An Enumeration of URLs. If the loader is closed, the Enumeration contains no elements.
/**
     * Returns an Enumeration of URLs representing all of the resources
     * on the URL search path having the specified name.
     *
     * @param name the resource name
     * @exception IOException if an I/O exception occurs
     * @return An {@code Enumeration} of {@code URL}s.
     *         If the loader is closed, the Enumeration contains no elements.
     */
    public Enumeration<URL> findResources(final String name)
        throws IOException
    {
        final Enumeration<URL> e = ucp.findResources(name, true);

        return new Enumeration<>() {
            private URL url = null;

            private boolean next() {
                if (url != null) {
                    return true;
                }
                do {
                    URL u = AccessController.doPrivileged(
                        new PrivilegedAction<>() {
                            public URL run() {
                                if (!e.hasMoreElements())
                                    return null;
                                return e.nextElement();
                            }
                        }, acc);
                    if (u == null)
                        break;
                    url = URLClassPath.checkURL(u);
                } while (url == null);
                return url != null;
            }

            public URL nextElement() {
                if (!next()) {
                    throw new NoSuchElementException();
                }
                URL u = url;
                url = null;
                return u;
            }

            public boolean hasMoreElements() {
                return next();
            }
        };
    }

    
Returns the permissions for the given codesource object.
The implementation of this method first calls super.getPermissions
and then adds permissions based on the URL of the codesource.


If the protocol of this URL is "jar", then the permission granted
is based on the permission that is required by the URL of the Jar
file.


If the protocol is "file" and there is an authority component, then
permission to connect to and accept connections from that authority
may be granted. If the protocol is "file"
and the path specifies a file, then permission to read that
file is granted. If protocol is "file" and the path is
a directory, permission is granted to read all files
and (recursively) all files and subdirectories contained in
that directory.


If the protocol is not "file", then permission
to connect to and accept connections from the URL's host is granted.

Params:
  • codesource – the codesource
Throws:
Returns:the permissions granted to the codesource
/**
     * Returns the permissions for the given codesource object.
     * The implementation of this method first calls super.getPermissions
     * and then adds permissions based on the URL of the codesource.
     * <p>
     * If the protocol of this URL is "jar", then the permission granted
     * is based on the permission that is required by the URL of the Jar
     * file.
     * <p>
     * If the protocol is "file" and there is an authority component, then
     * permission to connect to and accept connections from that authority
     * may be granted. If the protocol is "file"
     * and the path specifies a file, then permission to read that
     * file is granted. If protocol is "file" and the path is
     * a directory, permission is granted to read all files
     * and (recursively) all files and subdirectories contained in
     * that directory.
     * <p>
     * If the protocol is not "file", then permission
     * to connect to and accept connections from the URL's host is granted.
     * @param codesource the codesource
     * @exception NullPointerException if {@code codesource} is {@code null}.
     * @return the permissions granted to the codesource
     */
    protected PermissionCollection getPermissions(CodeSource codesource)
    {
        PermissionCollection perms = super.getPermissions(codesource);

        URL url = codesource.getLocation();

        Permission p;
        URLConnection urlConnection;

        try {
            urlConnection = url.openConnection();
            p = urlConnection.getPermission();
        } catch (java.io.IOException ioe) {
            p = null;
            urlConnection = null;
        }

        if (p instanceof FilePermission) {
            // if the permission has a separator char on the end,
            // it means the codebase is a directory, and we need
            // to add an additional permission to read recursively
            String path = p.getName();
            if (path.endsWith(File.separator)) {
                path += "-";
                p = new FilePermission(path, SecurityConstants.FILE_READ_ACTION);
            }
        } else if ((p == null) && (url.getProtocol().equals("file"))) {
            String path = url.getFile().replace('/', File.separatorChar);
            path = ParseUtil.decode(path);
            if (path.endsWith(File.separator))
                path += "-";
            p = new FilePermission(path, SecurityConstants.FILE_READ_ACTION);
        } else {
            /**
             * Not loading from a 'file:' URL so we want to give the class
             * permission to connect to and accept from the remote host
             * after we've made sure the host is the correct one and is valid.
             */
            URL locUrl = url;
            if (urlConnection instanceof JarURLConnection) {
                locUrl = ((JarURLConnection)urlConnection).getJarFileURL();
            }
            String host = locUrl.getHost();
            if (host != null && !host.isEmpty())
                p = new SocketPermission(host,
                                         SecurityConstants.SOCKET_CONNECT_ACCEPT_ACTION);
        }

        // make sure the person that created this class loader
        // would have this permission

        if (p != null) {
            final SecurityManager sm = System.getSecurityManager();
            if (sm != null) {
                final Permission fp = p;
                AccessController.doPrivileged(new PrivilegedAction<>() {
                    public Void run() throws SecurityException {
                        sm.checkPermission(fp);
                        return null;
                    }
                }, acc);
            }
            perms.add(p);
        }
        return perms;
    }

    
Creates a new instance of URLClassLoader for the specified URLs and parent class loader. If a security manager is installed, the loadClass method of the URLClassLoader returned by this method will invoke the SecurityManager.checkPackageAccess method before loading the class. 
Params:
  • urls – the URLs to search for classes and resources
  • parent – the parent class loader for delegation
Throws:
Returns:the resulting class loader
/**
     * Creates a new instance of URLClassLoader for the specified
     * URLs and parent class loader. If a security manager is
     * installed, the {@code loadClass} method of the URLClassLoader
     * returned by this method will invoke the
     * {@code SecurityManager.checkPackageAccess} method before
     * loading the class.
     *
     * @param urls the URLs to search for classes and resources
     * @param parent the parent class loader for delegation
     * @exception  NullPointerException if {@code urls} or any of its
     *             elements is {@code null}.
     * @return the resulting class loader
     */
    public static URLClassLoader newInstance(final URL[] urls,
                                             final ClassLoader parent) {
        // Save the caller's context
        final AccessControlContext acc = AccessController.getContext();
        // Need a privileged block to create the class loader
        URLClassLoader ucl = AccessController.doPrivileged(
            new PrivilegedAction<>() {
                public URLClassLoader run() {
                    return new FactoryURLClassLoader(null, urls, parent, acc);
                }
            });
        return ucl;
    }

    
Creates a new instance of URLClassLoader for the specified URLs and default parent class loader. If a security manager is installed, the loadClass method of the URLClassLoader returned by this method will invoke the SecurityManager.checkPackageAccess before loading the class. 
Params:
  • urls – the URLs to search for classes and resources
Throws:
Returns:the resulting class loader
/**
     * Creates a new instance of URLClassLoader for the specified
     * URLs and default parent class loader. If a security manager is
     * installed, the {@code loadClass} method of the URLClassLoader
     * returned by this method will invoke the
     * {@code SecurityManager.checkPackageAccess} before
     * loading the class.
     *
     * @param urls the URLs to search for classes and resources
     * @exception  NullPointerException if {@code urls} or any of its
     *             elements is {@code null}.
     * @return the resulting class loader
     */
    public static URLClassLoader newInstance(final URL[] urls) {
        // Save the caller's context
        final AccessControlContext acc = AccessController.getContext();
        // Need a privileged block to create the class loader
        URLClassLoader ucl = AccessController.doPrivileged(
            new PrivilegedAction<>() {
                public URLClassLoader run() {
                    return new FactoryURLClassLoader(urls, acc);
                }
            });
        return ucl;
    }

    static {
        SharedSecrets.setJavaNetURLClassLoaderAccess(
            new JavaNetURLClassLoaderAccess() {
                @Override
                public AccessControlContext getAccessControlContext(URLClassLoader u) {
                    return u.acc;
                }
            }
        );
        ClassLoader.registerAsParallelCapable();
    }
}

final class FactoryURLClassLoader extends URLClassLoader {

    static {
        ClassLoader.registerAsParallelCapable();
    }

    FactoryURLClassLoader(String name, URL[] urls, ClassLoader parent,
                          AccessControlContext acc) {
        super(name, urls, parent, acc);
    }

    FactoryURLClassLoader(URL[] urls, AccessControlContext acc) {
        super(urls, acc);
    }

    public final Class<?> loadClass(String name, boolean resolve)
        throws ClassNotFoundException
    {
        // First check if we have permission to access the package. This
        // should go away once we've added support for exported packages.
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            int i = name.lastIndexOf('.');
            if (i != -1) {
                sm.checkPackageAccess(name.substring(0, i));
            }
        }
        return super.loadClass(name, resolve);
    }
}