url.java

gcc的组建

  /**
   * This method parses a String representation of a URL within the
   * context of an existing URL.  Principally this means that any
   * fields not present the URL are inheritied from the context URL.
   * This allows relative URL's to be easily constructed.  If the
   * context argument is null, then a complete URL must be specified
   * in the URL string.  If the protocol parsed out of the URL is
   * different from the context URL's protocol, then then URL String
   * is also expected to be a complete URL.
   *
   * @param context The context on which to parse the specification
   * @param spec The string to parse an URL
   *
   * @exception MalformedURLException If a protocol handler cannot be found
   * for the URL cannot be parsed
   */
  public URL(URL context, String spec) throws MalformedURLException
  {
    this(context, spec, (URLStreamHandler) null);
  }

  /**
   * Creates an URL from given arguments
   * This method parses a String representation of a URL within the
   * context of an existing URL.  Principally this means that any fields
   * not present the URL are inheritied from the context URL.  This allows
   * relative URL's to be easily constructed.  If the context argument is
   * null, then a complete URL must be specified in the URL string.
   * If the protocol parsed out of the URL is different
   * from the context URL's protocol, then then URL String is also
   * expected to be a complete URL.
   * <p>
   * Additionally, this method allows the caller to specify a protocol handler
   * to use instead of  the default.  If this handler is specified, the caller
   * must have the "specifyStreamHandler" permission
   * (see <code>NetPermission</code>) or a <code>SecurityException</code>
   * will be thrown.
   *
   * @param context The context in which to parse the specification
   * @param spec The string to parse as an URL
   * @param ph The stream handler for the URL
   *
   * @exception MalformedURLException If a protocol handler cannot be found
   * or the URL cannot be parsed
   * @exception SecurityException If the <code>SecurityManager</code> exists
   * and does not allow the caller to specify its own protocol handler.
   *
   * @since 1.2
   */
  public URL(URL context, String spec, URLStreamHandler ph)
    throws MalformedURLException
  {
    /* A protocol is defined by the doc as the substring before a ':'
     * as long as the ':' occurs before any '/'.
     *
     * If context is null, then spec must be an absolute URL.
     *
     * The relative URL need not specify all the components of a URL.
     * If the protocol, host name, or port number is missing, the value
     * is inherited from the context.  A bare file component is appended
     * to the context's file.  The optional anchor is not inherited.
     */

    // If this is an absolute URL, then ignore context completely.
    // An absolute URL must have chars prior to "://" but cannot have a colon
    // right after the "://".  The second colon is for an optional port value
    // and implies that the host from the context is used if available.
    int colon;
    int slash = spec.indexOf('/');
    if ((colon = spec.indexOf("://", 1)) > 0
	&& ((colon < slash || slash < 0))
        && ! spec.regionMatches(colon, "://:", 0, 4))
      context = null;

    if ((colon = spec.indexOf(':')) > 0
        && (colon < slash || slash < 0))
      {
	// Protocol specified in spec string.
	protocol = spec.substring(0, colon).toLowerCase();
	if (context != null && context.protocol.equals(protocol))
	  {
	    // The 1.2 doc specifically says these are copied to the new URL.
	    host = context.host;
	    port = context.port;
            userInfo = context.userInfo;
	    authority = context.authority;
	  }
      }
    else if (context != null)
      {
	// Protocol NOT specified in spec string.
	// Use context fields (except ref) as a foundation for relative URLs.
	colon = -1;
	protocol = context.protocol;
	host = context.host;
	port = context.port;
        userInfo = context.userInfo;
	if (spec.indexOf(":/", 1) < 0)
	  {
	    file = context.file;
	    if (file == null || file.length() == 0)
	      file = "/";
	  }
	authority = context.authority;
      }
    else // Protocol NOT specified in spec. and no context available.
      throw new MalformedURLException("Absolute URL required with null"
				      + " context: " + spec);

    protocol = protocol.trim();

    if (ph != null)
      {
	SecurityManager s = System.getSecurityManager();
	if (s != null)
	  s.checkPermission(new NetPermission("specifyStreamHandler"));

	this.ph = ph;
      }
    else
      this.ph = getURLStreamHandler(protocol);

    if (this.ph == null)
      throw new MalformedURLException("Protocol handler not found: "
                                      + protocol);

    // JDK 1.2 doc for parseURL specifically states that any '#' ref
    // is to be excluded by passing the 'limit' as the indexOf the '#'
    // if one exists, otherwise pass the end of the string.
    int hashAt = spec.indexOf('#', colon + 1);

    try
      {
	this.ph.parseURL(this, spec, colon + 1,
	                 hashAt < 0 ? spec.length() : hashAt);
      }
    catch (URLParseError e)
      {
	throw new MalformedURLException(e.getMessage());
      }

    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 obj The URL to compare with
   *
   * @return true if the URL is equal, false otherwise
   */
  public boolean equals(Object obj)
  {
    if (! (obj instanceof URL))
      return false;

    return ph.equals(this, (URL) obj);
  }

  /**
   * 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 Object getContent() throws IOException
  {
    return openConnection().getContent();
  }

  /**
   * Gets the contents of this URL
   *
   * @param classes The allow classes for the content object.
   *
   * @return a context object for this URL.
   *
   * @exception IOException If an error occurs
   */
  public 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.
   *
   * @return The filename specified in this URL, or an empty string if empty.
   */
  public String getFile()
  {
    return file == null ? "" : file;
  }

  /**
   * Returns the path of the URL. This is the part of the file before any '?'
   * character.
   *
   * @return The path specified in this URL, or null if empty.
   *
   * @since 1.3
   */
  public String getPath()
  {
    // The spec says we need to return an empty string, but some
    // applications depends on receiving null when the path is empty.
    if (file == null)
      return null;
    int quest = file.indexOf('?');
    return quest < 0 ? getFile() : file.substring(0, quest);
  }

  /**
   * Returns the authority of the URL
   *
   * @return The authority specified in this URL.
   *
   * @since 1.3
   */
  public String getAuthority()
  {
    return authority;
  }

  /**
   * Returns the host of the URL
   *
   * @return The host specified in this 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.
   *
   * @return The default port of the current protocol.
   */
  public int getDefaultPort()
  {
    return ph.getDefaultPort();
  }

  /**
   * Returns the protocol of the URL
   *
   * @return The specified protocol.
   */
  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()
  {
    if (userInfo != null)
      return userInfo;
    int at = (host == null) ? -1 : 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 == null) ? -1 : file.indexOf('?');
    return quest < 0 ? null : file.substring(quest + 1, file.length());
  }

  /**
   * Returns a hashcode computed by the URLStreamHandler of this URL
   *
   * @return The hashcode for this URL.
   */