urlconnection.java

gcc的组建

    defaultUseCaches = use;
  }

  /**
   * Sets the value of the named request property
   *
   * @param key The name of the property
   * @param value The value of the property
   *
   * @exception IllegalStateException If already connected
   * @exception NullPointerException If key is null
   *
   * @see URLConnection#getRequestProperty(String key)
   * @see URLConnection#addRequestProperty(String key, String value)
   *
   * @since 1.4
   */
  public void setRequestProperty(String key, String value)
  {
    if (connected)
      throw new IllegalStateException("Already connected");

    if (key == null)
      throw new NullPointerException("key is null");

    // Do nothing unless overridden by subclasses that support setting
    // header fields in the request.
  }

  /**
   * Adds a new request property by a key/value pair.
   * This method does not overwrite existing properties with the same key.
   *
   * @param key Key of the property to add
   * @param value Value of the Property to add
   *
   * @exception IllegalStateException If already connected
   * @exception NullPointerException If key is null
   *
   * @see URLConnection#getRequestProperty(String key)
   * @see URLConnection#setRequestProperty(String key, String value)
   *
   * @since 1.4
   */
  public void addRequestProperty(String key, String value)
  {
    if (connected)
      throw new IllegalStateException("Already connected");

    if (key == null)
      throw new NullPointerException("key is null");

    // Do nothing unless overridden by subclasses that support adding
    // header fields in the request.
  }

  /**
   * Returns the value of the named request property.
   *
   * @param key The name of the property
   *
   * @return Value of the property
   *
   * @exception IllegalStateException If already connected
   *
   * @see URLConnection#setRequestProperty(String key, String value)
   * @see URLConnection#addRequestProperty(String key, String value)
   */
  public String getRequestProperty(String key)
  {
    if (connected)
      throw new IllegalStateException("Already connected");

    // Overridden by subclasses that support reading header fields from the
    // request.
    return null;
  }

  /**
   * Returns an unmodifiable Map containing the request properties.
   *
   * @return The map of properties
   *
   * @exception IllegalStateException If already connected
   *
   * @since 1.4
   */
  public Map getRequestProperties()
  {
    if (connected)
      throw new IllegalStateException("Already connected");

    // Overridden by subclasses that support reading header fields from the
    // request.
    return Collections.EMPTY_MAP;
  }

  /**
   * Sets the default value of a request property.  This will be used
   * for all connections unless the value of the property is manually
   * overridden.
   *
   * @param key The request property name the default is being set for
   * @param value The value to set the default to
   *
   * @deprecated 1.3 The method setRequestProperty should be used instead.
   * This method does nothing now.
   *
   * @see URLConnection#setRequestProperty(String key, String value)
   */
  public static void setDefaultRequestProperty(String key, String value)
  {
    // This method does nothing since JDK 1.3.
  }

  /**
   * Returns the default value of a request property.  This will be used
   * for all connections unless the value of the property is manually
   * overridden.
   *
   * @param key The request property to return the default value of
   *
   * @return The value of the default property or null if not available
   *
   * @deprecated 1.3 The method getRequestProperty should be used instead.
   * This method does nothing now.
   *
   * @see URLConnection#getRequestProperty(String key)
   */
  public static String getDefaultRequestProperty(String key)
  {
    // This method does nothing since JDK 1.3.
    return null;
  }

  /**
   * Sets the ContentHandlerFactory for an application.  This can be called
   * once and only once.  If it is called again, then an Error is thrown.
   * Unlike for other set factory methods, this one does not do a security
   * check prior to setting the factory.
   *
   * @param factory The ContentHandlerFactory for this application
   *
   * @exception Error If the factory has already been defined
   * @exception SecurityException If a security manager exists and its
   * checkSetFactory method doesn't allow the operation
   */
  public static synchronized void setContentHandlerFactory(ContentHandlerFactory factory)
  {
    if (URLConnection.factory != null)
      throw new Error("ContentHandlerFactory already set");

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

    URLConnection.factory = factory;
  }

  /**
   * Returns the MIME type of a file based on the name of the file.  This
   * works by searching for the file's extension in a list of file extensions
   * and returning the MIME type associated with it.  If no type is found,
   * then a MIME type of "application/octet-stream" will be returned.
   *
   * @param filename The filename to determine the MIME type for
   *
   * @return The MIME type String
   *
   * @specnote public since JDK 1.4
   */
  public static String guessContentTypeFromName(String filename)
  {
    int dot = filename.lastIndexOf(".");
    
    if (dot != -1)
      {
	if (dot == filename.length())
	  return "application/octet-stream";
	else
	  filename = filename.substring(dot + 1);
      }
    
    String type = MimeTypes.getMimeTypeFromExtension(filename);
    
    if (type == null)
      return"application/octet-stream";

    return type;
  }

  /**
   * Returns the MIME type of a stream based on the first few characters
   * at the beginning of the stream.  This routine can be used to determine
   * the MIME type if a server is believed to be returning an incorrect
   * MIME type.  This method returns "application/octet-stream" if it
   * cannot determine the MIME type.
   * <p>
   * NOTE: Overriding MIME types sent from the server can be obnoxious
   * to user's.  See Internet Exploder 4 if you don't believe me.
   *
   * @param is The InputStream to determine the MIME type from
   *
   * @return The MIME type
   *
   * @exception IOException If an error occurs
   */
  public static String guessContentTypeFromStream(InputStream is)
    throws IOException
  {
    is.mark(1024);
    // FIXME: Implement this. Use system mimetype informations (like "file").
    is.reset();
    return null;
  }

  /**
   * This method returns the <code>FileNameMap</code> object being used
   * to decode MIME types by file extension.
   *
   * @return The <code>FileNameMap</code>.
   *
   * @since 1.2
   */
  public static FileNameMap getFileNameMap()
  {
    return fileNameMap;
  }

  /**
   * This method sets the <code>FileNameMap</code> object being used
   * to decode MIME types by file extension.
   *
   * @param map The <code>FileNameMap</code>.
   *
   * @exception SecurityException If a security manager exists and its
   * checkSetFactory method doesn't allow the operation
   *
   * @since 1.2
   */
  public static void setFileNameMap(FileNameMap map)
  {
    // Throw an exception if an extant security manager precludes
    // setting the factory.
    SecurityManager s = System.getSecurityManager();
    if (s != null)
      s.checkSetFactory();

    fileNameMap = map;
  }

  private ContentHandler getContentHandler(String contentType)
  {
    // No content type so just handle it as the default.
    if (contentType == null || contentType.equals(""))
      return null;

    ContentHandler handler = null;

    // See if a handler has been cached for this content type.
    // For efficiency, if a content type has been searched for but not
    // found, it will be in the hash table but as the contentType String
    // instead of a ContentHandler.
    {
      Object cachedHandler;
      if ((cachedHandler = handlers.get(contentType)) != null)
	{
	  if (cachedHandler instanceof ContentHandler)
	    return (ContentHandler)cachedHandler;
	  else
	    return null;
	}
    }

    // If a non-default factory has been set, use it.
    if (factory != null)
      handler = factory.createContentHandler(contentType);

    // Now try default factory. Using this factory to instantiate built-in
    // content handlers is preferable  
    if (handler == null)
      handler = defaultFactory.createContentHandler(contentType);

    // User-set factory has not returned a handler. Use the default search 
    // algorithm.
    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.content.handler.pkgs");
	propVal = (propVal == null) ? "" : (propVal + "|");
	propVal = propVal + "gnu.java.net.content|sun.net.www.content";

	// Replace the '/' character in the content type with '.' and
	// all other non-alphabetic, non-numeric characters with '_'.
	char[] cArray = contentType.toCharArray();
	for (int i = 0; i < cArray.length; i++)
	  {
	    if (cArray[i] == '/')
	      cArray[i] = '.';
	    else if (! ((cArray[i] >= 'A' && cArray[i] <= 'Z') || 
			(cArray[i] >= 'a' && cArray[i] <= 'z') ||
			(cArray[i] >= '0' && cArray[i] <= '9')))
	      cArray[i] = '_';
	  }
	String contentClass = new String(cArray);

	// See if a class of this content type exists in any of the packages.
	StringTokenizer pkgPrefix = new StringTokenizer(propVal, "|");
	do
	  {
	    String facName = pkgPrefix.nextToken() + "." + contentClass;
	    try
	      {
		handler =
		  (ContentHandler) Class.forName(facName).newInstance();
	      }
	    catch (Exception e)
	      {
		// Can't instantiate; handler still null, go on to next element.
	      }
	  } while ((handler == null ||
		    ! (handler instanceof ContentHandler)) &&
		   pkgPrefix.hasMoreTokens());
      }

    // Update the hashtable with the new content handler.
    if (handler instanceof ContentHandler)
      {
	handlers.put(contentType, handler);
	return handler;
      }

    // For efficiency on subsequent searches, put a dummy entry in the hash
    // table for content types that don't have a non-default ContentHandler.
    handlers.put(contentType, contentType);
    return null;
  }
  
  // We don't put these in a static initializer, because it creates problems
  // with initializer co-dependency: SimpleDateFormat's constructors eventually 
  // depend on URLConnection (via the java.text.*Symbols classes).
  private static synchronized void initializeDateFormats()
  {
    if (dateformats_initialized)
      return;

    Locale locale = new Locale("En", "Us", "Unix");
    dateFormats = new SimpleDateFormat[3];
    dateFormats[0] =
      new SimpleDateFormat("EEE, dd MMM yyyy hh:mm:ss 'GMT'", locale);
    dateFormats[1] =
      new SimpleDateFormat("EEEE, dd-MMM-yy hh:mm:ss 'GMT'", locale);
    dateFormats[2] = new SimpleDateFormat("EEE MMM d hh:mm:ss yyyy", locale);
    dateformats_initialized = true;
  }
}