urlstreamhandler.java

gcc的组建

      {
	// 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
   *
   * @return True if both URLs point to the same file, false otherwise.
   *
   * @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)
      return false;
    int p1 = url1.getPort();
    if (p1 == -1)
      p1 = url1.ph.getDefaultPort();
    int p2 = url2.getPort();
    if (p2 == -1)
      p2 = url2.ph.getDefaultPort();
    if (p1 != p2)
      return false;
    String s1;
    String 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
   *
   * @return True if both given URLs are equal, false otherwise.
   */
  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.
   *
   * @param url1 The first URL.
   * @param url2 The second URL.
   *
   * @return True if both URLs contain the same host.
   */
  protected boolean hostsEqual(URL url1, URL url2)
  {
    InetAddress addr1 = getHostAddress(url1);
    InetAddress addr2 = getHostAddress(url2);

    if (addr1 != null && addr2 != null)
      return addr1.equals(addr2);

    String host1 = url1.getHost();
    String host2 = url2.getHost();

    if (host1 != null && host2 != null)
      return host1.equalsIgnoreCase(host2);

    return host1 == null && host2 == null;
  }

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

    if (hostname.equals(""))
      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.
   *
   * @return The default port number.
   */
  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.
   *
   * @param url The URL to calc the hashcode for.
   *
   * @return The hashcode for the given URL.
   */
  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
   *
   * @return A string representation of the url
   */
  protected String toExternalForm(URL url)
  {
    String protocol;
    String file;
    String ref;
    String authority;

    protocol = url.getProtocol();
    authority = url.getAuthority();
    if (authority == null)
      authority = "";
    
    file = url.getFile();
    ref = url.getRef();

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

    if (protocol.length() > 0)
      {
	sb.append(protocol);
	sb.append(":");
      }
    
    // If we have superfluous leading slashes (that means, at least 2)
    // we always add the authority component ("//" + host) to
    // avoid ambiguity. Otherwise we would generate an URL like
    // proto://home/foo
    // where we meant: 
    // host: <empty> - file: //home/foo
    // but URL spec says it is:
    // host: home - file: /foo
    if (authority.length() != 0 || file.startsWith("//") )
      sb.append("//").append(authority).append(file);
    else
      sb.append(file);

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

    return sb.toString();
  }
}