urlstreamhandler.java

俄罗斯高人Mamaich的Pocket gcc编译器（运行在PocketPC上）的全部源代码。

    // Process "/../" correctly.  This probably isn't very efficient in
    // the general case, but it's probably not bad most of the time.
    while ((index = file.indexOf("/../")) >= 0)
      {
	// Strip of the previous directory - if it exists.
	int previous = file.lastIndexOf('/', index - 1);
	if (previous >= 0)
	  file = file.substring(0, previous) + file.substring(index + 3);
	else
	  break;
      }
    return file; 
  }

  /**
   * Compares two URLs, excluding the fragment component
   *
   * @param url1 The first url
   * @param url2 The second url to compare with the first
   * 
   * @specnote Now protected
   */
  protected boolean sameFile(URL url1, URL url2)
  {
    if (url1 == url2)
      return true;
    // This comparison is very conservative.  It assumes that any
    // field can be null.
    if (url1 == null || url2 == null || url1.getPort() != url2.getPort())
      return false;
    String s1, s2;
    s1 = url1.getProtocol();
    s2 = url2.getProtocol();
    if (s1 != s2 && (s1 == null || ! s1.equals(s2)))
      return false;
    s1 = url1.getHost();
    s2 = url2.getHost();
    if (s1 != s2 && (s1 == null || ! s1.equals(s2)))
      return false;
    s1 = canonicalizeFilename(url1.getFile());
    s2 = canonicalizeFilename(url2.getFile());
    if (s1 != s2 && (s1 == null || ! s1.equals(s2)))
      return false;
    return true;
  }

  /**
   * This methods sets the instance variables representing the various fields
   * of the URL to the values passed in.
   *
   * @param u The URL to modify
   * @param protocol The protocol to set
   * @param host The host name to et
   * @param port The port number to set
   * @param file The filename to set
   * @param ref The reference
   *
   * @exception SecurityException If the protocol handler of the URL is
   * different from this one
   *
   * @deprecated 1.2 Please use
   * #setURL(URL,String,String,int,String,String,String,String);
   */
  protected void setURL(URL u, String protocol, String host, int port,
			String file, String ref)
  {
    u.set(protocol, host, port, file, ref);
  }

  /**
   * Sets the fields of the URL argument to the indicated values
   *
   * @param u The URL to modify
   * @param protocol The protocol to set
   * @param host The host name to set
   * @param port The port number to set
   * @param authority The authority to set
   * @param userInfo The user information to set
   * @param path The path/filename to set
   * @param query The query part to set
   * @param ref The reference
   *
   * @exception SecurityException If the protocol handler of the URL is
   * different from this one
   */
  protected void setURL(URL u, String protocol, String host, int port,
			String authority, String userInfo, String path,
			String query, String ref)
  {
    u.set(protocol, host, port, authority, userInfo, path, query, ref);
  }

  /**
   * Provides the default equals calculation. May be overidden by handlers for
   * other protocols that have different requirements for equals(). This method
   * requires that none of its arguments is null. This is guaranteed by the
   * fact that it is only called by java.net.URL class.
   *
   * @param url1 An URL object
   * @param url2 An URL object
   */
  protected boolean equals (URL url1, URL url2)
  {
    // This comparison is very conservative.  It assumes that any
    // field can be null.
    return (url1.getPort () == url2.getPort ()
	    && ((url1.getProtocol () == null && url2.getProtocol () == null)
		|| (url1.getProtocol () != null
			&& url1.getProtocol ().equals (url2.getProtocol ())))
	    && ((url1.getUserInfo () == null && url2.getUserInfo () == null)
                || (url1.getUserInfo () != null
			&& url1.getUserInfo ().equals(url2.getUserInfo ())))
	    && ((url1.getAuthority () == null && url2.getAuthority () == null)
                || (url1.getAuthority () != null
			&& url1.getAuthority ().equals(url2.getAuthority ())))
	    && ((url1.getHost () == null && url2.getHost () == null)
		|| (url1.getHost () != null
			&& url1.getHost ().equals(url2.getHost ())))
	    && ((url1.getPath () == null && url2.getPath () == null)
		|| (url1.getPath () != null
			&& url1.getPath ().equals (url2.getPath ())))
	    && ((url1.getQuery () == null && url2.getQuery () == null)
                || (url1.getQuery () != null
			&& url1.getQuery ().equals(url2.getQuery ())))
	    && ((url1.getRef () == null && url2.getRef () == null)
		|| (url1.getRef () != null
			&& url1.getRef ().equals(url2.getRef ()))));
  }

  /**
   * Compares the host components of two URLs.
   *
   * @exception UnknownHostException If an unknown host is found
   */
  protected boolean hostsEqual (URL url1, URL url2)
    throws UnknownHostException
  {
    InetAddress addr1 = InetAddress.getByName (url1.getHost ());
    InetAddress addr2 = InetAddress.getByName (url2.getHost ());

    return addr1.equals (addr2);
  }

  /**
   * Get the IP address of our host. An empty host field or a DNS failure will
   * result in a null return.
   */
  protected InetAddress getHostAddress (URL url)
  {
    String hostname = url.getHost ();

    if (hostname == "")
      return null;
    
    try
      {
        return InetAddress.getByName (hostname);
      }
    catch (UnknownHostException e)
      {
	return null;
      }
  }

  /**
   * Returns the default port for a URL parsed by this handler. This method is
   * meant to be overidden by handlers with default port numbers.
   */
  protected int getDefaultPort ()
  {
    return -1;
  }

  /**
   * Provides the default hash calculation. May be overidden by handlers for
   * other protocols that have different requirements for hashCode calculation.
   */
  protected int hashCode (URL url)
  {
    return url.getProtocol ().hashCode () +
           ((url.getHost () == null) ? 0 : url.getHost ().hashCode ()) +
	   url.getFile ().hashCode() +
	   url.getPort ();
  }

  /**
   * This method converts a URL object into a String.  This method creates
   * Strings in the mold of http URL's, so protocol handlers which use URL's
   * that have a different syntax should override this method
   *
   * @param url The URL object to convert
   */
  protected String toExternalForm(URL u)
  {
    String protocol, host, file, ref;
    int port;

    protocol = u.getProtocol();

    // JDK 1.2 online doc infers that host could be null because it
    // explicitly states that file cannot be null, but is silent on host.
    host = u.getHost();
    if (host == null)
      host = "";

    port = u.getPort();
    file = u.getFile();
    ref = u.getRef();

    // Guess a reasonable size for the string buffer so we have to resize
    // at most once.
    int size = protocol.length() + host.length() + file.length() + 24;
    StringBuffer sb = new StringBuffer(size);

    sb.append(protocol);
    sb.append(':');

    if (host.length() != 0)
      sb.append("//").append(host);

    // Note that this produces different results from JDK 1.2 as JDK 1.2
    // ignores a non-default port if host is null or "".  That is inconsistent
    // with the spec since the result of this method is spec'ed so it can be
    // used to construct a new URL that is equivalent to the original.
    boolean port_needed = port > 0 && port != getDefaultPort();
    if (port_needed)
      sb.append(':').append(port);

    sb.append(file);

    if (ref != null)
      sb.append('#').append(ref);

    return sb.toString();
  }
}