url.java

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    if (hashAt >= 0)
      ref = spec.substring(hashAt + 1);

    hashCode = hashCode();			// Used for serialization.
  }

  /**
   * Test another URL for equality with this one.  This will be true only if
   * the argument is non-null and all of the fields in the URL's match 
   * exactly (ie, protocol, host, port, file, and ref).  Overrides
   * Object.equals(), implemented by calling the equals method of the handler.
   *
   * @param url The URL to compare with
   *
   * @return true if the URL is equal, false otherwise
   */
  public boolean equals(Object obj)
  {
    if (obj == null || ! (obj instanceof URL))
      return false;

    URL uObj = (URL) obj;

    return handler.equals (this, uObj);
  }

  /**
   * Returns the contents of this URL as an object by first opening a
   * connection, then calling the getContent() method against the connection
   *
   * @return A content object for this URL
   * @exception IOException If opening the connection or getting the
   * content fails.
   *
   * @since 1.3
   */
  public final Object getContent() throws IOException
  {
    return openConnection().getContent();
  }

  /**
   * Gets the contents of this URL
   *
   * @exception IOException If an error occurs
   */
  public final Object getContent (Class[] classes) throws IOException
  {
    // FIXME: implement this
    return getContent();
  }

  /**
   * Returns the file portion of the URL.
   * Defined as <code>path[?query]</code>.
   * Returns the empty string if there is no file portion.
   */
  public String getFile()
  {
    return file == null ? "" : file;
  }

  /**
   * Returns the path of the URL. This is the part of the file before any '?'
   * character.
   *
   * @since 1.3
   */
  public String getPath()
  {
    int quest = file.indexOf('?');
    return quest < 0 ? file : file.substring(0, quest);
  }

  /**
   * Returns the authority of the URL
   * 
   * @since 1.3
   */
  public String getAuthority()
  {
    return authority;
  }

  /**
   * Returns the host of the URL
   */
  public String getHost()
  {
    int at = (host == null) ? -1 : host.indexOf('@');
    return at < 0 ? host : host.substring(at + 1, host.length());
  }

  /**
   * Returns the port number of this URL or -1 if the default port number is
   * being used.
   *
   * @return The port number
   *
   * @see #getDefaultPort()
   */
  public int getPort()
  {
    return port;
  }

  /**
   * Returns the default port of the URL. If the StreamHandler for the URL
   * protocol does not define a default port it returns -1.
   */
  public int getDefaultPort()
  {
    return handler.getDefaultPort();
  }

  /**
   * Returns the protocol of the URL
   */
  public String getProtocol()
  {
    return protocol;
  }

  /**
   * Returns the ref (sometimes called the "# reference" or "anchor") portion
   * of the URL.
   *
   * @return The ref
   */
  public String getRef()
  {
    return ref;
  }

  /**
   * Returns the user information of the URL. This is the part of the host
   * name before the '@'.
   *
   * @return the user at a particular host or null when no user defined.
   */
  public String getUserInfo ()
  {
    int at = host.indexOf('@');
    return at < 0 ? null : host.substring(0, at);
  }

  /**
   * Returns the query of the URL. This is the part of the file before the
   * '?'.
   *
   * @ return the query part of the file, or null when there is no query part.
   */
  public String getQuery ()
  {
    int quest = file.indexOf('?');
    return quest < 0 ? null : file.substring(quest + 1, file.length());
  }

  /**
   * Returns a hashcode computed by the URLStreamHandler of this URL
   */
  public int hashCode()
  {
    if (hashCode != 0)
      return hashCode;		// Use cached value if available.
    else
      return handler.hashCode (this);
  }

  /**
   * Returns a URLConnection object that represents a connection to the remote
   * object referred to by the URL. The URLConnection is created by calling the
   * openConnection() method of the protocol handler
   *
   * @return A URLConnection for this URL
   * @exception IOException If an error occurs
   */
  public URLConnection openConnection() throws IOException
  {
    return handler.openConnection(this);
  }

  /**
   * Opens a connection to this URL and returns an InputStream for reading
   * from that connection
   *
   * @exception IOException If an error occurs
   */
  public final InputStream openStream() throws IOException
  {
    return openConnection().getInputStream();
  }

  /**
   * Tests whether or not another URL refers to the same "file" as this one.
   * This will be true if and only if the passed object is not null, is a
   * URL, and matches all fields but the ref (ie, protocol, host, port,
   * and file);
   *
   * @param url The URL object to test with
   *
   * @return true if URL matches this URL's file, false otherwise
   */
  public boolean sameFile(URL other)
  {
    return handler.sameFile(this, other);
  }

  /**
   * Sets the specified fields of the URL. This is not a public method so
   * that only URLStreamHandlers can modify URL fields. This might be called
   * by the <code>parseURL()</code> method in that class. URLs are otherwise
   * constant.
   *
   * @param protocol The protocol name for this URL
   * @param host The hostname or IP address for this URL
   * @param port The port number of this URL
   * @param file The "file" portion of this URL.
   * @param ref The anchor portion of this URL.
   */
  protected void set(String protocol, String host, int port, String file,
		     String ref)
  {
    // TBD: Theoretically, a poorly written StreamHandler could pass an
    // invalid protocol.  It will cause the handler to be set to null
    // thus overriding a valid handler.  Callers of this method should
    // be aware of this.
    this.handler = getURLStreamHandler(protocol);
    this.protocol = protocol.toLowerCase();
    this.authority = null;
    this.port = port;
    this.host = host;
    this.file = file;
    this.ref = ref;
    hashCode = hashCode();			// Used for serialization.
  }

  /**
   * Sets the specified fields of the URL. This is not a public method so
   * that only URLStreamHandlers can modify URL fields. URLs are otherwise
   * constant.
   *
   * @since 1.3
   */
  protected void set(String protocol, String host, int port,
		     String authority, String userInfo,
		     String path, String query, String ref)
  {
    // TBD: Theoretically, a poorly written StreamHandler could pass an
    // invalid protocol.  It will cause the handler to be set to null
    // thus overriding a valid handler.  Callers of this method should
    // be aware of this.
    this.handler = getURLStreamHandler(protocol);
    this.protocol = protocol.toLowerCase();
    if (userInfo == null)
      this.host = host;
    else
      this.host = userInfo + "@" + host;
    this.port = port;
    if (query == null)
      this.file = path;
    else
      this.file = path + "?" + query;
    this.ref = ref;
    hashCode = hashCode();			// Used for serialization.
  }

  /**
   * Sets the URLStreamHandlerFactory for this class.  This factory is
   * responsible for returning the appropriate protocol handler for
   * a given URL.
   *
   * @param fac The URLStreamHandlerFactory class to use
   *
   * @exception Error If the factory is alread set.
   * @exception SecurityException If a security manager exists and its
   * checkSetFactory method doesn't allow the operation
   */
  public static synchronized void
	setURLStreamHandlerFactory(URLStreamHandlerFactory fac)
  {
    if (factory != null)
      throw new Error("URLStreamHandlerFactory already set");

    // Throw an exception if an extant security mgr precludes
    // setting the factory.
    SecurityManager s = System.getSecurityManager();
    if (s != null)
      s.checkSetFactory();
    factory = fac;
  }

  /**
   * Returns a String representing this URL.  The String returned is
   * created by calling the protocol handler's toExternalForm() method.
   *
   * @return A string for this URL
   */
  public String toExternalForm()
  {
    // Identical to toString().
    return handler.toExternalForm(this);
  }

  /**
   * Returns a String representing this URL.  Identical to toExternalForm().
   * The value returned is created by the protocol handler's 
   * toExternalForm method.  Overrides Object.toString()
   *
   * @return A string for this URL
   */
  public String toString()
  {
    // Identical to toExternalForm().
    return handler.toExternalForm(this);
  }

  private static synchronized URLStreamHandler
    getURLStreamHandler(String protocol)
  {
    URLStreamHandler handler;

    // See if a handler has been cached for this protocol.
    if ((handler = (URLStreamHandler) handlers.get(protocol)) != null)
      return handler;

    // If a non-default factory has been set, use it to find the protocol.
    if (factory != null)
      handler = factory.createURLStreamHandler(protocol);
    else if (protocol.equals ("core"))
      {
 	handler = new gnu.gcj.protocol.core.Handler ();
      }
    else if (protocol.equals ("file"))
      {
	// This is an interesting case.  It's tempting to think that we
	// could call Class.forName ("gnu.gcj.protocol.file.Handler") to
	// get the appropriate class.  Unfortunately, if we do that the
	// program will never terminate, because getURLStreamHandler is
	// eventually called by Class.forName.
	//
	// Treating "file" as a special case is the minimum that will
	// fix this problem.  If other protocols are required in a
	// statically linked application they will need to be handled in
	// the same way as "file".
	handler = new gnu.gcj.protocol.file.Handler ();
      }

    // Non-default factory may have returned null or a factory wasn't set.
    // Use the default search algorithm to find a handler for this protocol.
    if (handler == null)
      {
	// Get the list of packages to check and append our default handler
	// to it, along with the JDK specified default as a last resort.
	// Except in very unusual environments the JDK specified one shouldn't
	// ever be needed (or available).
	String propVal = System.getProperty("java.protocol.handler.pkgs");
	propVal = (propVal == null) ? "" : (propVal + "|");
	propVal = propVal + "gnu.gcj.protocol|sun.net.www.protocol";

	StringTokenizer pkgPrefix = new StringTokenizer(propVal, "|");
	do
	  {
	    String facName = pkgPrefix.nextToken() + "." + protocol +
				".Handler";
	    try
	      {
		handler =
		  (URLStreamHandler) Class.forName(facName).newInstance();
	      }
	    catch (Exception e)
	      {
		// Can't instantiate; handler still null, go on to next element.
	      }
	  } while ((handler == null ||
		    ! (handler instanceof URLStreamHandler)) &&
		   pkgPrefix.hasMoreTokens());
      }

    // Update the hashtable with the new protocol handler.
    if (handler != null)
      if (handler instanceof URLStreamHandler)
	handlers.put(protocol, handler);
      else
	handler = null;

    return handler;
  }

  private void readObject(ObjectInputStream ois)
    throws IOException, ClassNotFoundException
  {
    ois.defaultReadObject();
    this.handler = getURLStreamHandler(protocol);
    if (this.handler == null)
      throw new IOException("Handler for protocol " + protocol + " not found");
  }

  private void writeObject(ObjectOutputStream oos) throws IOException
  {
    oos.defaultWriteObject();
  }
}