urlconnection.java

gcc的组建

  }

  /**
   * Returns the ifModified since instance variable.  If this value is non
   * zero and the underlying protocol supports it, the actual document will
   * not be fetched unless it has been modified since this time.  The value
   * returned will be 0 if this feature is disabled or the time expressed
   * as the number of seconds since midnight 1/1/1970 GMT otherwise
   *
   * @return The ifModifiedSince value
   */
  public long getIfModifiedSince()
  {
    return ifModifiedSince;
  }

  /**
   * Returns the default value used to determine whether or not caching
   * of documents will be done when possible.
   *
   * @return true if caches will be used, false otherwise
   */
  public boolean getDefaultUseCaches()
  {
    return defaultUseCaches;
  }

  /**
   * Sets the default value used to determine whether or not caching
   * of documents will be done when possible.
   *
   * @param use true to use caches if possible by default, false otherwise
   */
  public void setDefaultUseCaches(boolean use)
  {
    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)
  {
    return getFileNameMap().getContentTypeFor(filename.toLowerCase());
  }

  /**
   * 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
  {
    return "application/octet-stream";
  }

  /**
   * 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 synchronized FileNameMap getFileNameMap()
  {
    // Delayed initialization.
    if (fileNameMap == null)
      fileNameMap = new MimeTypeMapper();

    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 synchronized 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;

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

    // Then try our default class.
    try
      {
	String typeClass = contentType.replace('/', '.');

	// Deal with "Content-Type: text/html; charset=ISO-8859-1".
	int parameterBegin = typeClass.indexOf(';');
	if (parameterBegin >= 1)
	  typeClass = typeClass.substring(0, parameterBegin);

	Class cls = Class.forName("gnu.java.net.content." + typeClass);
	Object obj = cls.newInstance();

	if (obj instanceof ContentHandler)
	  {
	    handler = (ContentHandler) obj;
	    return handler;
	  }
      }
    catch (ClassNotFoundException e)
      {
	// Ignore.
      }
    catch (InstantiationException e)
      {
	// Ignore.
      }
    catch (IllegalAccessException e)
      {
	// Ignore.
      }

    return handler;
  }
  
  // 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;
  }
}