urlclassloader.java

gcc的组建

    Certificate[] getCertificates()
    {
      // We have to get the entry from the jar file again, because the
      // certificates will not be available until the entire entry has
      // been read.
      return ((JarEntry) ((JarURLLoader) loader).jarfile.getEntry(name))
        .getCertificates();
    }

    URL getURL()
    {
      try
        {
          return new URL(((JarURLLoader) loader).baseJarURL, name,
                         loader.classloader.getURLStreamHandler("jar"));
        }
      catch (MalformedURLException e)
        {
          InternalError ie = new InternalError();
          ie.initCause(e);
          throw ie;
        }
    }
  }

  /**
   * Loader for remote directories.
   */
  static final class RemoteURLLoader extends URLLoader
  {
    private final String protocol;

    RemoteURLLoader(URLClassLoader classloader, URL url)
    {
      super(classloader, url);
      protocol = url.getProtocol();
    }

    /**
     * Get a remote resource.
     * Returns null if no such resource exists.
     */
    Resource getResource(String name)
    {
      try
        {
          URL url =
            new URL(baseURL, name, classloader.getURLStreamHandler(protocol));
          URLConnection connection = url.openConnection();

          // Open the connection and check the stream
          // just to be sure it exists.
          int length = connection.getContentLength();
          InputStream stream = connection.getInputStream();

          // We can do some extra checking if it is a http request
          if (connection instanceof HttpURLConnection)
            {
              int response =
                ((HttpURLConnection) connection).getResponseCode();
              if (response / 100 != 2)
                return null;
            }

          if (stream != null)
            return new RemoteResource(this, name, url, stream, length);
          else
            return null;
        }
      catch (IOException ioe)
        {
          return null;
        }
    }
  }

  /**
   * A resource from some remote location.
   */
  static final class RemoteResource extends Resource
  {
    private final URL url;
    private final InputStream stream;
    private final int length;

    RemoteResource(RemoteURLLoader loader, String name, URL url,
                   InputStream stream, int length)
    {
      super(loader);
      this.url = url;
      this.stream = stream;
      this.length = length;
    }

    InputStream getInputStream() throws IOException
    {
      return stream;
    }

    public int getLength()
    {
      return length;
    }

    public URL getURL()
    {
      return url;
    }
  }

  /**
   * A <code>FileURLLoader</code> is a type of <code>URLLoader</code>
   * only loading from file url.
   */
  static final class FileURLLoader extends URLLoader
  {
    File dir; //the file for this file url

    FileURLLoader(URLClassLoader classloader, URL url)
    {
      super(classloader, url);
      dir = new File(baseURL.getFile());
    }

    /** get resource with the name "name" in the file url */
    Resource getResource(String name)
    {
      try 
 	{
 	  File file = new File(dir, name).getCanonicalFile();
 	  if (file.exists() && !file.isDirectory())
 	    return new FileResource(this, file);
 	}
      catch (IOException e)
 	{
 	  // Fall through...
 	}
      return null;
    }
  }

  static final class FileResource extends Resource
  {
    final File file;

    FileResource(FileURLLoader loader, File file)
    {
      super(loader);
      this.file = file;
    }

    InputStream getInputStream() throws IOException
    {
      return new FileInputStream(file);
    }

    public int getLength()
    {
      return (int) file.length();
    }

    public URL getURL()
    {
      try
        {
          return file.toURL();
        }
      catch (MalformedURLException e)
        {
          InternalError ie = new InternalError();
          ie.initCause(e);
          throw ie;
        }
    }
  }

  // Constructors

  /**
   * Creates a URLClassLoader that gets classes from the supplied URLs.
   * To determine if this classloader may be created the constructor of
   * the super class (<code>SecureClassLoader</code>) is called first, which
   * can throw a SecurityException. Then the supplied URLs are added
   * in the order given to the URLClassLoader which uses these URLs to
   * load classes and resources (after using the default parent ClassLoader).
   *
   * @param urls Locations that should be searched by this ClassLoader when
   * resolving Classes or Resources.
   * @exception SecurityException if the SecurityManager disallows the
   * creation of a ClassLoader.
   * @see SecureClassLoader
   */
  public URLClassLoader(URL[] urls) throws SecurityException
  {
    super();
    this.factory = null;
    this.securityContext = null;
    addURLs(urls);
  }

  /**
   * Creates a <code>URLClassLoader</code> that gets classes from the supplied
   * <code>URL</code>s.
   * To determine if this classloader may be created the constructor of
   * the super class (<code>SecureClassLoader</code>) is called first, which
   * can throw a SecurityException. Then the supplied URLs are added
   * in the order given to the URLClassLoader which uses these URLs to
   * load classes and resources (after using the supplied parent ClassLoader).
   * @param urls Locations that should be searched by this ClassLoader when
   * resolving Classes or Resources.
   * @param parent The parent class loader used before trying this class
   * loader.
   * @exception SecurityException if the SecurityManager disallows the
   * creation of a ClassLoader.
   * @exception SecurityException
   * @see SecureClassLoader
   */
  public URLClassLoader(URL[] urls, ClassLoader parent)
    throws SecurityException
  {
    super(parent);
    this.factory = null;
    this.securityContext = null;
    addURLs(urls);
  }

  // Package-private to avoid a trampoline constructor.
  /**
   * Package-private constructor used by the static
   * <code>newInstance(URL[])</code> method.  Creates an
   * <code>URLClassLoader</code> with the given parent but without any
   * <code>URL</code>s yet. This is used to bypass the normal security
   * check for creating classloaders, but remembers the security
   * context which will be used when defining classes.  The
   * <code>URL</code>s to load from must be added by the
   * <code>newInstance()</code> method in the security context of the
   * caller.
   *
   * @param securityContext the security context of the unprivileged code.
   */
  URLClassLoader(ClassLoader parent, AccessControlContext securityContext)
  {
    super(parent);
    this.factory = null;
    this.securityContext = securityContext;
  }

  /**
   * Creates a URLClassLoader that gets classes from the supplied URLs.
   * To determine if this classloader may be created the constructor of
   * the super class (<CODE>SecureClassLoader</CODE>) is called first, which
   * can throw a SecurityException. Then the supplied URLs are added
   * in the order given to the URLClassLoader which uses these URLs to
   * load classes and resources (after using the supplied parent ClassLoader).
   * It will use the supplied <CODE>URLStreamHandlerFactory</CODE> to get the
   * protocol handlers of the supplied URLs.
   * @param urls Locations that should be searched by this ClassLoader when
   * resolving Classes or Resources.
   * @param parent The parent class loader used before trying this class
   * loader.
   * @param factory Used to get the protocol handler for the URLs.
   * @exception SecurityException if the SecurityManager disallows the
   * creation of a ClassLoader.
   * @exception SecurityException
   * @see SecureClassLoader
   */
  public URLClassLoader(URL[] urls, ClassLoader parent,
                        URLStreamHandlerFactory factory)
    throws SecurityException
  {
    super(parent);
    this.securityContext = null;
    this.factory = factory;
    addURLs(urls);

    // If this factory is still not in factoryCache, add it,
    //   since we only support three protocols so far, 5 is enough
    //   for cache initial size
    synchronized (factoryCache)
      {
        if (factory != null && factoryCache.get(factory) == null)
          factoryCache.put(factory, new HashMap(5));
      }
  }

  // Methods

  /**
   * Adds a new location to the end of the internal URL store.
   * @param newUrl the location to add
   */
  protected void addURL(URL newUrl)
  {
    urls.add(newUrl);
    addURLImpl(newUrl);
  }

  private void addURLImpl(URL newUrl)
  {
    synchronized (this)
      {
        if (newUrl == null)
          return; // Silently ignore...

	// Reset the toString() value.
	thisString = null;

        // Check global cache to see if there're already url loader
        // for this url.
        URLLoader loader = (URLLoader) urlloaders.get(newUrl);
        if (loader == null)
          {
            String file = newUrl.getFile();
            String protocol = newUrl.getProtocol();

            // Check that it is not a directory
            if (! (file.endsWith("/") || file.endsWith(File.separator)))
              loader = new JarURLLoader(this, newUrl);
            else if ("file".equals(protocol))
              loader = new FileURLLoader(this, newUrl);
            else
              loader = new RemoteURLLoader(this, newUrl);

            // Cache it.
            urlloaders.put(newUrl, loader);
          }

	urlinfos.add(loader);

	Vector extraUrls = loader.getClassPath();
	if (extraUrls != null)
	  {
	    Iterator it = extraUrls.iterator();
	    while (it.hasNext())
	      {
		URL url = (URL)it.next();
		URLLoader extraLoader = (URLLoader) urlloaders.get(url);
		if (! urlinfos.contains (extraLoader))
		  addURLImpl(url);
	      }
	  }

      }
  }

  /**
   * Adds an array of new locations to the end of the internal URL
   * store.  Called from the the constructors. Should not call to the
   * protected addURL() method since that can be overridden and
   * subclasses are not yet in a good state at this point.
   * jboss 4.0.3 for example depends on this.
   *
   * @param newUrls the locations to add
   */
  private void addURLs(URL[] newUrls)
  {
    for (int i = 0; i < newUrls.length; i++)
      {
	urls.add(newUrls[i]);
	addURLImpl(newUrls[i]);
      }
  }

  /**
   * Look in both Attributes for a given value.  The first Attributes
   * object, if not null, has precedence.
   */
  private String getAttributeValue(Attributes.Name name, Attributes first,
				   Attributes second)
  {
    String result = null;
    if (first != null)
      result = first.getValue(name);
    if (result == null)
      result = second.getValue(name);
    return result;
  }

  /**
   * Defines a Package based on the given name and the supplied manifest
   * information. The manifest indicates the title, version and
   * vendor information of the specification and implementation and whether the
   * package is sealed. If the Manifest indicates that the package is sealed
   * then the Package will be sealed with respect to the supplied URL.
   *
   * @param name The name of the package
   * @param manifest The manifest describing the specification,
   * implementation and sealing details of the package
   * @param url the code source url to seal the package
   * @return the defined Package
   * @throws IllegalArgumentException If this package name already exists
   * in this class loader
   */
  protected Package definePackage(String name, Manifest manifest, URL url)
    throws IllegalArgumentException
  {
    // Compute the name of the package as it may appear in the
    // Manifest.
    StringBuffer xform = new StringBuffer(name);
    for (int i = xform.length () - 1; i >= 0; --i)
      if (xform.charAt(i) == '.')
	xform.setCharAt(i, '/');
    xform.append('/');
    String xformName = xform.toString();

    Attributes entryAttr = manifest.getAttributes(xformName);
    Attributes attr = manifest.getMainAttributes();

    String specTitle
      = getAttributeValue(Attributes.Name.SPECIFICATION_TITLE,