urlconnection.java

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  public Permission getPermission() throws IOException
  {
    // Subclasses may override this.
    return new AllPermission();
  }

  /**
   * Returns an InputStream for this connection.  As this default
   * implementation returns null, subclasses should override this method
   *
   * @return An InputStream for this connection
   *
   * @exception IOException If an error occurs
   * @exception UnknownServiceException If the protocol does not support input
   */
  public InputStream getInputStream() throws IOException
  {
    // Subclasses for specific protocols override this.
    throw new UnknownServiceException("Protocol " + url.getProtocol() +
			" does not support input.");
  }

  /**
   * Returns an OutputStream for this connection.  As this default
   * implementation returns null, subclasses should override this method
   *
   * @return An OutputStream for this connection
   *
   * @exception IOException If an error occurs
   * @exception UnknownServiceException If the protocol does not support output
   */
  public OutputStream getOutputStream() throws IOException
  {
    // Subclasses for specific protocols override this.
    throw new UnknownServiceException("Protocol " + url.getProtocol() +
			" does not support output.");
  }

  /**
   * The methods prints the value of this object as a String by calling the
   * toString() method of its associated URL.  Overrides Object.toString()
   * 
   * @return A String representation of this object
   */
  public String toString()
  {
    return this.getClass().getName() + ":" + url.toString();
  }

  /**
   * Returns the value of a flag indicating whether or not input is going
   * to be done for this connection.  This default to true unless the
   * doOutput flag is set to false, in which case this defaults to false.
   * 
   * @param input <code>true</code> if input is to be done,
   * <code>false</code> otherwise
   *
   * @exception IllegalStateException If already connected
   */
  public void setDoInput(boolean input)
  {
    if (connected)
      throw new IllegalStateException ("Already connected");

    doInput = input;
  }

  /**
   * Returns the value of a flag indicating whether or not input is going
   * to be done for this connection.  This default to true unless the
   * doOutput flag is set to false, in which case this defaults to false.
   *
   * @return true if input is to be done, false otherwise
   */
  public boolean getDoInput()
  {
    return doInput;
  }

  /**
   * Returns a boolean flag indicating whether or not output will be done
   * on this connection.  The default value is false, so this method can
   * be used to override the default
   *
   * @param output ture if output is to be done, false otherwise
   *
   * @exception IllegalStateException If already connected
   */
  public void setDoOutput(boolean output)
  {
    if (connected)
      throw new IllegalStateException ("Already connected");

    doOutput = output;
  }

  /**
   * Returns a boolean flag indicating whether or not output will be done
   * on this connection.  This defaults to false.
   *
   * @return true if output is to be done, false otherwise
   */
  public boolean getDoOutput()
  {
    return doOutput;
  }

  /**
   * Sets a boolean flag indicating whether or not user interaction is
   * allowed for this connection.  (For example, in order to prompt for
   * username and password info.
   *
   * @param allow true if user interaction should be allowed, false otherwise.
   *
   * @exception IllegalStateException If already connected
   */
  public void setAllowUserInteraction(boolean allow)
  {
    allowUserInteraction = allow;
  }

  /**
   * Returns a boolean flag indicating whether or not user interaction is
   * allowed for this connection.  (For example, in order to prompt for
   * username and password info.
   *
   * @return true if user interaction is allowed, false otherwise
   */
  public boolean getAllowUserInteraction()
  {
    return allowUserInteraction;
  }

  /**
   * Sets the default flag for whether or not interaction with a user
   * is allowed.  This will be used for all connections unless overridden
   *
   * @param allow true to allow user interaction, false otherwise
   */
  public static void setDefaultAllowUserInteraction(boolean allow)
  {
    defaultAllowUserInteraction = allow;
  }

  /**
   * Returns the default flag for whether or not interaction with a user
   * is allowed.  This will be used for all connections unless overridden
   *
   * @return true if user interaction is allowed, false otherwise
   */
  public static boolean getDefaultAllowUserInteraction()
  {
    return defaultAllowUserInteraction;
  }

  /**
   * Sets a boolean flag indicating whether or not caching will be used
   * (if possible) to store data downloaded via the connection.
   *
   * @param usecaches The new value
   *
   * @exception IllegalStateException If already connected
   */
  public void setUseCaches(boolean usecaches)
  {
    if (connected)
      throw new IllegalStateException ("Already connected");

    useCaches = usecaches;
  }

  /**
   * Returns a boolean flag indicating whether or not caching will be used
   * (if possible) to store data downloaded via the connection.
   *
   * @return true if caching should be used if possible, false otherwise
   */
  public boolean getUseCaches()
  {
    return useCaches;
  }

  /**
   * Sets 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
   * passed should  be 0 if this feature is to be disabled or the time expressed
   * as the number of seconds since midnight 1/1/1970 GMT otherwise.
   *
   * @param ifmodifiedsince The new value in milliseconds
   * since January 1, 1970 GMT
   *
   * @exception IllegalStateException If already connected
   */
  public void setIfModifiedSince(long ifmodifiedsince)
  {
    if (connected)
      throw new IllegalStateException ("Already connected");

    ifModifiedSince = ifmodifiedsince;
  }

  /**
   * 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 defaultusecaches)
  {
    defaultUseCaches = defaultusecaches;
  }

  /**
   * 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;
  }

  /**
   * Set's 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 fac)
  {
    if (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();

    factory = fac;
  }

  /**
   * 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 set 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 mgr precludes
    // setting the factory.
    SecurityManager s = System.getSecurityManager();
    if (s != null)
      s.checkSetFactory();

    fileNameMap = map;
  }
}