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URL and URLStreamHandler merge with Classpath


Hi,

The following merges URL and URLStreamHandler with GNU Classpath.
It does not yet merge the actual URL handlers (URL.getStreamHandler() is
still different). No (Mauve) regressions or new successes on the libgcj
side, but on the Classpath (+ Kissme) side there were some improvements.

2002-11-21  Mark Wielaard  <mark@klomp.org>

        * java/net/URL.java: Merge with Classpath (partly).
        * java/net/URLStreamHandler: Merge with Classpath.

OK to commit?

Cheers,

Mark
Index: java/net/URL.java
===================================================================
RCS file: /cvs/gcc/gcc/libjava/java/net/URL.java,v
retrieving revision 1.15
diff -u -r1.15 URL.java
--- java/net/URL.java	1 Nov 2002 06:35:14 -0000	1.15
+++ java/net/URL.java	22 Nov 2002 02:28:26 -0000
@@ -1,56 +1,180 @@
-// URL.java - A Uniform Resource Locator.
+/* URL.java -- Uniform Resource Locator Class
+   Copyright (C) 1998, 1999, 2000, 2002 Free Software Foundation, Inc.
 
-/* Copyright (C) 1999, 2000, 2002  Free Software Foundation
+This file is part of GNU Classpath.
 
-   This file is part of libgcj.
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+ 
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+02111-1307 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
 
-This software is copyrighted work licensed under the terms of the
-Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
-details.  */
 
 package java.net;
 
-import java.io.*;
+import java.io.InputStream;
+import java.io.IOException;
+import java.io.Serializable;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
 import java.util.Hashtable;
 import java.util.StringTokenizer;
 
-/**
- * @author Warren Levy <warrenl@cygnus.com>
- * @date March 4, 1999.
- */
 
-/**
+/*
  * Written using on-line Java Platform 1.2 API Specification, as well
  * as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
  * Status:  Believed complete and correct.
  */
 
+/**
+  * This final class represents an Internet Uniform Resource Locator (URL).
+  * For details on the syntax of URL's and what they can be used for,
+  * refer to RFC 1738, available from <a 
+  * href="http://ds.internic.net/rfcs/rfc1738.txt";>http://ds.internic.net/rfcs/rfc1738.txt</a>
+  * <p>
+  * There are a great many protocols supported by URL's such as "http",
+  * "ftp", and "file".  This object can handle any arbitrary URL for which
+  * a URLStreamHandler object can be written.  Default protocol handlers
+  * are provided for the "http" and "ftp" protocols.  Additional protocols
+  * handler implementations may be provided in the future.  In any case,
+  * an application or applet can install its own protocol handlers that
+  * can be "chained" with other protocol hanlders in the system to extend
+  * the base functionality provided with this class. (Note, however, that
+  * unsigned applets cannot access properties by default or install their
+  * own protocol handlers).
+  * <p>
+  * This chaining is done via the system property java.protocol.handler.pkgs
+  * If this property is set, it is assumed to be a "|" separated list of
+  * package names in which to attempt locating protocol handlers.  The
+  * protocol handler is searched for by appending the string 
+  * ".<protocol>.Handler" to each packed in the list until a hander is found.
+  * If a protocol handler is not found in this list of packages, or if the
+  * property does not exist, then the default protocol handler of
+  * "gnu.java.net.<protocol>.Handler" is tried.  If this is
+  * unsuccessful, a MalformedURLException is thrown.
+  * <p>
+  * All of the constructor methods of URL attempt to load a protocol
+  * handler and so any needed protocol handlers must be installed when
+  * the URL is constructed.
+  * <p>
+  * Here is an example of how URL searches for protocol handlers.  Assume
+  * the value of java.protocol.handler.pkgs is "com.foo|com.bar" and the
+  * URL is "news://comp.lang.java.programmer";.  URL would looking the 
+  * following places for protocol handlers:
+  * <p><pre>
+  * com.foo.news.Handler
+  * com.bar.news.Handler
+  * gnu.java.net.news.Handler
+  * </pre><p>
+  * If the protocol handler is not found in any of those locations, a
+  * MalformedURLException would be thrown.
+  * <p>
+  * Please note that a protocol handler must be a subclass of
+  * URLStreamHandler.
+  *
+  * @author Aaron M. Renn (arenn@urbanophile.com)
+  * @author Warren Levy <warrenl@cygnus.com>
+  *
+  * @see URLStreamHandler
+  */
 public final class URL implements Serializable
 {
+  /**
+   * The name of the protocol for this URL.
+   * The protocol is always stored in lower case.
+   */
   private String protocol;
+
+  /**
+   * The "authority" portion of the URL.
+   */
   private String authority;
-  private String userInfo;
+
+  /**
+   * The hostname or IP address of this protocol.
+   * This includes a possible user. For example <code>joe@some.host.net</code>.
+   */
   private String host;
+
+  /**
+   * The port number of this protocol or -1 if the port number used is
+   * the default for this protocol.
+   */
   private int port = -1;	// Initialize for constructor using context.
+
+  /**
+   * The "file" portion of the URL. It is defined as <code>path[?query]</code>.
+   */
   private String file;
-  private String query;
+
+  /**
+   * The anchor portion of the URL.
+   */
   private String ref;
+
+  /**
+   * This is the hashCode for this URL
+   */
   private int hashCode = 0;
+
+  /**
+   * The protocol handler in use for this URL
+   */
   transient private URLStreamHandler handler;
+
+  /**
+   * This a table where we cache protocol handlers to avoid the overhead
+   * of looking them up each time.
+   */
   private static Hashtable handlers = new Hashtable();
+
+  /**
+   * If an application installs its own protocol handler factory, this is
+   * where we keep track of it.
+   */
   private static URLStreamHandlerFactory factory;
 
   private static final long serialVersionUID = -7627629688361524110L;
 
   /**
-   * Creates an URL object from the given arguments
-   *
-   * @param protocol The protocol of the URL
-   * @param host The host of the URL
-   * @param port The port of the URL
-   * @param file The file of the URL
+   * Constructs a URL and loads a protocol handler for the values passed as
+   * arguments.
+   * 
+   * @param protocol The protocol for this URL ("http", "ftp", etc)
+   * @param host The hostname or IP address to connect to
+   * @param port The port number to use, or -1 to use the protocol's
+   * default port
+   * @param file The "file" portion of the URL.
    *
-   * @exception MalformedURLException If an error occurs
+   * @exception MalformedURLException If a protocol handler cannot be loaded or
+   * a parse error occurs.
    */
   public URL(String protocol, String host, int port, String file)
     throws MalformedURLException
@@ -59,13 +183,15 @@
   }
 
   /**
-   * Creates an URL object from the given arguments
+   * Constructs a URL and loads a protocol handler for the values passed in
+   * as arugments.  Uses the default port for the protocol.
    *
-   * @param protocol The protocol of the URL
-   * @param host The host of the URL
-   * @param file The file of the URL
+   * @param protocol The protocol for this URL ("http", "ftp", etc)
+   * @param host The hostname or IP address for this URL
+   * @param file The "file" portion of this URL.
    *
-   * @exception MalformedURLException If an error occurs
+   * @exception MalformedURLException If a protocol handler cannot be loaded or
+   * a parse error occurs.
    */
   public URL(String protocol, String host, String file)
     throws MalformedURLException
@@ -73,19 +199,26 @@
     this(protocol, host, -1, file, null);
   }
 
+
   /**
-   * Creates an URL object from the given arguments
-   *
-   * @param protocol The protocol of the URL
-   * @param host The host of the URL
-   * @param port The port of the URL
-   * @param file The file of the URL
-   * @param handler The stream handler for the URL
-   *
-   * @exception MalformedURLException If an error occurs
-   * @exception SecurityException If  a security manager exists and its
-   * checkPermission method doesn't allow specifying a stream handler
-   * explicitly
+   * This method initializes a new instance of <code>URL</code> with the
+   * specified protocol, host, port, and file.  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 protocol The protocol for this URL ("http", "ftp", etc)
+   * @param host The hostname or IP address to connect to
+   * @param port The port number to use, or -1 to use the protocol's default
+   * port
+   * @param file The "file" portion of the URL.
+   * @param handler The protocol handler to use with this URL.
+   *
+   * @exception MalformedURLException If no protocol handler can be loaded
+   * for the specified protocol.
+   * @exception SecurityException If the <code>SecurityManager</code> exists
+   * and does not allow the caller to specify its own protocol handler.
    *
    * @since 1.2
    */
@@ -94,18 +227,18 @@
   {
     if (protocol == null)
       throw new MalformedURLException("null protocol");
-    this.protocol = protocol;
+    this.protocol = protocol.toLowerCase();
 
     if (handler != null)
       {
-	SecurityManager s = System.getSecurityManager ();
+	SecurityManager s = System.getSecurityManager();
 	if (s != null)
 	  s.checkPermission (new NetPermission ("specifyStreamHandler"));
 
         this.handler = handler;
       }
     else
-      this.handler = setURLStreamHandler(protocol);
+      this.handler = getURLStreamHandler(protocol);
 
     if (this.handler == null)
       throw new MalformedURLException (
@@ -113,9 +246,7 @@
 
     this.host = host;
     this.port = port;
-    this.userInfo = null;
     this.authority = null;
-    this.query = null;
 
     int hashAt = file.indexOf('#');
     if (hashAt < 0)
@@ -132,24 +263,37 @@
   }
 
   /**
-   * Creates an URL object from the given arguments
-   * 
-   * @param spec The string to parse an URL
+   * Initializes a URL from a complete string specification such as
+   * "http://www.urbanophile.com/arenn/";.  First the protocol name is parsed
+   * out of the string.  Then a handler is located for that protocol and
+   * the parseURL() method of that protocol handler is used to parse the
+   * remaining fields.
    *
-   * @exception MalformedURLException If an error occurs
+   * @param spec The complete String representation of a URL
+   *
+   * @exception MalformedURLException If a protocol handler cannot be found
+   * or the URL cannot be parsed
    */
   public URL(String spec) throws MalformedURLException
   {
     this((URL) null, spec, (URLStreamHandler) null);
   }
 
-  /**
-   * Creates an URL object from the 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.
+   *
    * @param context The context on which to parse the specification
    * @param spec The string to parse an URL
    *
-   * @exception MalformedURLException If an error occurs
+   * @exception MalformedURLException If a protocol handler cannot be found 
+   * for the URL cannot be parsed
    */
   public URL(URL context, String spec) throws MalformedURLException
   {
@@ -158,16 +302,30 @@
 
   /**
    * 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 handler The stream handler for the URL
    *
-   * @exception MalformedURLException If an error occurs
-   * @exception SecurityException If  a security manager exists and its
-   * checkPermission method doesn't allow specifying a stream handler
-   * explicitly
-   * 
+   * @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 handler)
@@ -198,16 +356,14 @@
 	(colon < (slash = spec.indexOf('/')) || slash < 0))
       {
 	// Protocol specified in spec string.
-	protocol = spec.substring(0, colon);
+	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;
 	    file = context.file;
-	    userInfo = context.userInfo;
 	    authority = context.authority;
-	    query = context.query;
 	  }
       }
     else if (context != null)
@@ -219,9 +375,7 @@
 	host = context.host;
 	port = context.port;
 	file = context.file;
-        userInfo = context.userInfo;
         authority = context.authority;
-        query = context.query;
       }
     else	// Protocol NOT specified in spec. and no context available.
       throw new
@@ -236,7 +390,7 @@
         this.handler = handler;
       }
     else
-      this.handler = setURLStreamHandler(protocol);
+      this.handler = getURLStreamHandler(protocol);
 
     if (this.handler == null)
       throw new MalformedURLException("Protocol handler not found: "
@@ -255,7 +409,14 @@
   }
 
   /**
-   * Checks if two URLs are equal
+   * 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 url The URL to compare with
+   *
+   * @return true if the URL is equal, false otherwise
    */
   public boolean equals(Object obj)
   {
@@ -268,9 +429,12 @@
   }
 
   /**
-   * Gets the contents of this URL
+   * Returns the contents of this URL as an object by first opening a
+   * connection, then calling the getContent() method against the connection
    *
-   * @exception IOException If an error occurs
+   * @return A content object for this URL
+   * @exception IOException If opening the connection or getting the
+   * content fails.
    *
    * @since 1.3
    */
@@ -291,15 +455,18 @@
   }
 
   /**
-   * Returns the file of the URL
+   * Returns the file portion of the URL.
+   * Defined as <code>path[?query]</code>.
+   * Returns the empty string if there is no file portion.
    */
   public String getFile()
   {
-    return file;
+    return file == null ? "" : file;
   }
 
   /**
-   * Returns the path of the URL
+   * Returns the path of the URL. This is the part of the file before any '?'
+   * character.
    *
    * @since 1.3
    */
@@ -324,11 +491,17 @@
    */
   public String getHost()
   {
-    return host;
+    int at = (host == null) ? -1 : host.indexOf('@');
+    return at < 0 ? host : host.substring(at + 1, host.length());
   }
 
   /**
-   * Returns of port of the URL
+   * 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()
   {
@@ -336,11 +509,12 @@
   }
 
   /**
-   * Returns the default port of the URL
+   * Returns the default port of the URL. If the StreamHandler for the URL
+   * protocol does not define a default port it returns -1.
    */
   public int getDefaultPort()
   {
-    return 0;
+    return handler.getDefaultPort();
   }
 
   /**
@@ -351,13 +525,22 @@
     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
+   * 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 ()
   {
@@ -366,11 +549,15 @@
   }
 
   /**
-   * Returns the query of the URL
+   * 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 ()
   {
-    return query;
+    int quest = file.indexOf('?');
+    return quest < 0 ? null : file.substring(quest + 1, file.length());
   }
 
   /**
@@ -378,20 +565,6 @@
    */
   public int hashCode()
   {
-    // JCL book says this is computed using (only) the hashcodes of the 
-    // protocol, host and file fields.  Empirical evidence indicates this
-    // is probably XOR in JDK 1.1.  In JDK 1.2 it seems to be a sum including
-    // the port.
-    //
-    // JDK 1.2 online doc infers that host could be null because it
-    // explicitly states that file cannot be null but is silent on host.
-    // A simple example with protocol "http" (hashcode 3213448), host null,
-    // file "/" (hashcode 47) produced a hashcode (3213494) which appeared
-    // to be the sum of the two hashcodes plus the port.  Another example
-    // using "/index.html" for file bore this out; as well as "#" for file
-    // (which was reduced to "" with a hashcode of zero).  A "" host also
-    // causes the port number and the two hashcodes to be summed.
-
     if (hashCode != 0)
       return hashCode;		// Use cached value if available.
     else
@@ -400,8 +573,10 @@
 
   /**
    * Returns a URLConnection object that represents a connection to the remote
-   * object referred to by the URL
+   * object referred to by the URL. The URLConnection is created by calling the
+   * openConnection() method of the protocol handler
    *
+   * @return A URLConnection for this URL
    * @exception IOException If an error occurs
    */
   public URLConnection openConnection() throws IOException
@@ -420,6 +595,16 @@
     return openConnection().getInputStream();
   }
 
+  /**
+   * Tests whether or not another URL refers to the same "file" as this one.
+   * This will be true if and only if the passed object is not null, is a
+   * URL, and matches all fields but the ref (ie, protocol, host, port,
+   * and file);
+   *
+   * @param url The URL object to test with
+   *
+   * @return true if URL matches this URL's file, false otherwise
+   */
   public boolean sameFile(URL other)
   {
     return handler.sameFile(this, other);
@@ -427,8 +612,15 @@
 
   /**
    * Sets the specified fields of the URL. This is not a public method so
-   * that only URLStreamHandlers can modify URL fields. URLs are otherwise
-   * constant
+   * that only URLStreamHandlers can modify URL fields. This might be called
+   * by the <code>parseURL()</code> method in that class. URLs are otherwise
+   * constant.
+   *
+   * @param protocol The protocol name for this URL
+   * @param host The hostname or IP address for this URL
+   * @param port The port number of this URL
+   * @param file The "file" portion of this URL.
+   * @param ref The anchor portion of this URL.
    */
   protected void set(String protocol, String host, int port, String file,
 		     String ref)
@@ -437,14 +629,12 @@
     // invalid protocol.  It will cause the handler to be set to null
     // thus overriding a valid handler.  Callers of this method should
     // be aware of this.
-    this.handler = setURLStreamHandler(protocol);
-    this.protocol = protocol;
+    this.handler = getURLStreamHandler(protocol);
+    this.protocol = protocol.toLowerCase();
     this.authority = null;
-    this.userInfo = null;
     this.port = port;
     this.host = host;
     this.file = file;
-    this.query = null;
     this.ref = ref;
     hashCode = hashCode();			// Used for serialization.
   }
@@ -452,7 +642,7 @@
   /**
    * Sets the specified fields of the URL. This is not a public method so
    * that only URLStreamHandlers can modify URL fields. URLs are otherwise
-   * constant
+   * constant.
    *
    * @since 1.3
    */
@@ -464,8 +654,8 @@
     // invalid protocol.  It will cause the handler to be set to null
     // thus overriding a valid handler.  Callers of this method should
     // be aware of this.
-    this.handler = setURLStreamHandler(protocol);
-    this.protocol = protocol;
+    this.handler = getURLStreamHandler(protocol);
+    this.protocol = protocol.toLowerCase();
     if (userInfo == null)
       this.host = host;
     else
@@ -480,9 +670,13 @@
   }
 
   /**
-   * Sets an application's URLStreamHandlerFactory
+   * Sets the URLStreamHandlerFactory for this class.  This factory is
+   * responsible for returning the appropriate protocol handler for
+   * a given URL.
+   *
+   * @param fac The URLStreamHandlerFactory class to use
    *
-   * @exception Error If the application has already set a factory
+   * @exception Error If the factory is alread set.
    * @exception SecurityException If a security manager exists and its
    * checkSetFactory method doesn't allow the operation
    */
@@ -500,19 +694,33 @@
     factory = fac;
   }
 
+  /**
+   * Returns a String representing this URL.  The String returned is
+   * created by calling the protocol handler's toExternalForm() method.
+   *
+   * @return A string for this URL
+   */
   public String toExternalForm()
   {
     // Identical to toString().
     return handler.toExternalForm(this);
   }
 
+  /**
+   * Returns a String representing this URL.  Identical to toExternalForm().
+   * The value returned is created by the protocol handler's 
+   * toExternalForm method.  Overrides Object.toString()
+   *
+   * @return A string for this URL
+   */
   public String toString()
   {
     // Identical to toExternalForm().
     return handler.toExternalForm(this);
   }
 
-  private URLStreamHandler setURLStreamHandler(String protocol)
+  private static synchronized URLStreamHandler
+    getURLStreamHandler(String protocol)
   {
     URLStreamHandler handler;
 
@@ -532,7 +740,7 @@
 	// This is an interesting case.  It's tempting to think that we
 	// could call Class.forName ("gnu.gcj.protocol.file.Handler") to
 	// get the appropriate class.  Unfortunately, if we do that the
-	// program will never terminate, because setURLStreamHandler is
+	// program will never terminate, because getURLStreamHandler is
 	// eventually called by Class.forName.
 	//
 	// Treating "file" as a special case is the minimum that will
@@ -587,7 +795,7 @@
     throws IOException, ClassNotFoundException
   {
     ois.defaultReadObject();
-    this.handler = setURLStreamHandler(protocol);
+    this.handler = getURLStreamHandler(protocol);
     if (this.handler == null)
       throw new IOException("Handler for protocol " + protocol + " not found");
   }
Index: java/net/URLStreamHandler.java
===================================================================
RCS file: /cvs/gcc/gcc/libjava/java/net/URLStreamHandler.java,v
retrieving revision 1.12
diff -u -r1.12 URLStreamHandler.java
--- java/net/URLStreamHandler.java	21 Oct 2002 04:53:50 -0000	1.12
+++ java/net/URLStreamHandler.java	22 Nov 2002 02:28:26 -0000
@@ -1,28 +1,78 @@
-// URLStreamHandler.java - Superclass of all stream protocol handlers.
+/* URLStreamHandler.java -- Abstract superclass for all protocol handlers
+   Copyright (C) 1998, 1999, 2002 Free Software Foundation, Inc.
 
-/* Copyright (C) 1999, 2002  Free Software Foundation
+This file is part of GNU Classpath.
 
-   This file is part of libgcj.
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+ 
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+02111-1307 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
 
-This software is copyrighted work licensed under the terms of the
-Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
-details.  */
 
 package java.net;
 
 import java.io.IOException;
 
-/**
- * @author Warren Levy <warrenl@cygnus.com>
- * @date March 4, 1999.
- */
-
-/**
+/*
  * Written using on-line Java Platform 1.2 API Specification, as well
  * as "The Java Class Libraries", 2nd edition (Addison-Wesley, 1998).
  * Status:  Believed complete and correct.
  */
 
+/**
+ * This class is the superclass of all URL protocol handlers.  The URL
+ * class loads the appropriate protocol handler to establish a connection
+ * to a (possibly) remote service (eg, "http", "ftp") and to do protocol
+ * specific parsing of URL's.  Refer to the URL class documentation for
+ * details on how that class locates and loads protocol handlers.
+ * <p>
+ * A protocol handler implementation should override the openConnection()
+ * method, and optionally override the parseURL() and toExternalForm()
+ * methods if necessary. (The default implementations will parse/write all
+ * URL's in the same form as http URL's).  A protocol  specific subclass 
+ * of URLConnection will most likely need to be created as well.
+ * <p>
+ * Note that the instance methods in this class are called as if they
+ * were static methods.  That is, a URL object to act on is passed with
+ * every call rather than the caller assuming the URL is stored in an
+ * instance variable of the "this" object.
+ * <p>
+ * The methods in this class are protected and accessible only to subclasses.
+ * URLStreamConnection objects are intended for use by the URL class only,
+ * not by other classes (unless those classes are implementing protocols).
+ *
+ * @author Aaron M. Renn (arenn@urbanophile.com)
+ * @author Warren Levy (warrenl@cygnus.com)
+ * 
+ * @see URL
+ */
 public abstract class URLStreamHandler
 {
   /**
@@ -33,8 +83,15 @@
   }
 
   /**
-   * Opens a connection to the object referenced by the URL argument.
-   * This method should be overridden by a subclass.
+   * Returns a URLConnection for the passed in URL.  Note that this should
+   * not actually create the connection to the (possibly) remote host, but
+   * rather simply return a URLConnection object.  The connect() method of
+   * URL connection is used to establish the actual connection, possibly
+   * after the caller sets up various connection options.
+   *
+   * @param url The URL to get a connection object for
+   *
+   * @return A URLConnection object for the given URL
    *
    * @exception IOException If an error occurs
    */
@@ -42,28 +99,33 @@
     throws IOException;
 
   /**
-   * Pasrses the given URL
-   *
-   * @param u The URL to parse
-   * @param spec The specification to use
-   * @param start The character index at which to begin parsing. This is just
-   * past the ':' (if there is one) that specifies the determination of the
-   * protocol name
-   * @param limit The character position to stop parsing at. This is the end
-   * of the string or the position of the "#" character, if present. All
-   * information after the sharp sign indicates an anchor
-   */
-  protected void parseURL(URL u, String spec, int start, int limit)
-  {
-    String host = u.getHost();
-    int port = u.getPort();
-    String file = u.getFile();
+   * This method parses the string passed in as a URL and set's the
+   * instance data fields in the URL object passed in to the various values
+   * parsed out of the string.  The start parameter is the position to start
+   * scanning the string.  This is usually the position after the ":" which
+   * terminates the protocol name.  The end parameter is the position to
+   * stop scanning.  This will be either the end of the String, or the
+   * position of the "#" character, which separates the "file" portion of
+   * the URL from the "anchor" portion.
+   * <p>
+   * This method assumes URL's are formatted like http protocol URL's, so 
+   * subclasses that implement protocols with URL's the follow a different 
+   * syntax should override this method.  The lone exception is that if
+   * the protocol name set in the URL is "file", this method will accept
+   * a an empty hostname (i.e., "file:///"), which is legal for that protocol
+   *
+   * @param url The URL object in which to store the results
+   * @param spec The String-ized URL to parse
+   * @param start The position in the string to start scanning from
+   * @param end The position in the string to stop scanning
+   */
+  protected void parseURL(URL url, String spec, int start, int end)
+  {
+    String host = url.getHost();
+    int port = url.getPort();
+    String file = url.getFile();
+    String ref = url.getRef();
     
-    /* TBD: The JDK 1.2 doc specifically says that limit is the position
-     * to stop parsing at and that it will be either the end of the string
-     * or the position of '#'; thus the doc infers that this method does
-     * not set the ref.
-     */
     if (spec.regionMatches (start, "//", 0, 2))
       {
 	int hostEnd;
@@ -74,7 +136,7 @@
 	if (slash >= 0) 
 	  hostEnd = slash;
         else
-	  hostEnd = limit;
+	  hostEnd = end;
 
 	host = spec.substring (start, hostEnd);
 	
@@ -103,28 +165,46 @@
     else if (host == null) 
       host = "";
 
-    if (start < limit && spec.charAt(start) == '/') 
-      {
-	// This is an absolute path name; ignore any file context.
-	file = spec.substring(start, limit);
-      } 
-    else if (file == null || file.length() <= 0)
+    if (file == null || file.length() == 0
+	|| (start < end && spec.charAt(start) == '/')) 
       {
 	// No file context available; just spec for file.
-	file = spec.substring(start, limit);
-      }
-    else if (start < limit)
+	// Or this is an absolute path name; ignore any file context.
+	file = spec.substring(start, end);
+	ref = null;
+      } 
+    else if (start < end)
       {
 	// Context is available, but only override it if there is a new file.
 	file = file.substring(0, file.lastIndexOf('/'))
-		+ '/' + spec.substring(start, limit);
+		+ '/' + spec.substring(start, end);
+	ref = null;
+      }
+
+    if (ref == null)
+      {
+	// Normally there should be no '#' in the file part,
+	// but we are nice.
+	int hash = file.indexOf('#');
+	if (hash != -1)
+	  {
+	    ref = file.substring(hash + 1, file.length());
+	    file = file.substring(0, hash);
+	  }
       }
 
-    u.set(u.getProtocol(), host, port, file, u.getRef());
+    // XXX - Classpath used to call PlatformHelper.toCanonicalForm() on
+    // the file part. It seems like overhead, but supposedly there is some
+    // benefit in windows based systems (it also lowercased the string).
+
+    setURL(url, url.getProtocol(), host, port, file, ref);
   }
   
   private static String canonicalizeFilename(String file)
   {
+    // XXX - GNU Classpath has an implementation that might be more appropriate
+    // for Windows based systems (gnu.java.io.PlatformHelper.toCanonicalForm)
+
     int index;
 
     // Replace "/./" with "/".  This probably isn't very efficient in
@@ -179,7 +259,8 @@
   }
 
   /**
-   * Sets the fields of the URL argument to the indicated values
+   * 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
@@ -317,38 +398,53 @@
   }
 
   /**
-   * Converts an URL of a specific protocol to a string
+   * 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 u The URL to convert
+   * @param url The URL object to convert
    */
   protected String toExternalForm(URL u)
   {
-    String resStr, host, file, ref;
+    String protocol, host, file, ref;
     int port;
 
-    resStr = u.getProtocol() + ":";
+    protocol = u.getProtocol();
+
+    // JDK 1.2 online doc infers that host could be null because it
+    // explicitly states that file cannot be null, but is silent on host.
     host = u.getHost();
+    if (host == null)
+      host = "";
+
     port = u.getPort();
     file = u.getFile();
     ref = u.getRef();
 
-    // JDK 1.2 online doc infers that host could be null because it
-    // explicitly states that file cannot be null, but is silent on host.
-    //
+    // Guess a reasonable size for the string buffer so we have to resize
+    // at most once.
+    int size = protocol.length() + host.length() + file.length() + 24;
+    StringBuffer sb = new StringBuffer(size);
+
+    sb.append(protocol);
+    sb.append(':');
+
+    if (host.length() != 0)
+      sb.append("//").append(host);
+
     // Note that this produces different results from JDK 1.2 as JDK 1.2
     // ignores a non-default port if host is null or "".  That is inconsistent
     // with the spec since the result of this method is spec'ed so it can be
     // used to construct a new URL that is equivalent to the original.
-    if (host == null)
-      host = "";
-    if (port >= 0 || ! (host.length() == 0))
-      resStr = resStr + "//" + host + (port < 0 ? "" : ":" + port);
+    boolean port_needed = port >= 0 && port != getDefaultPort();
+    if (port_needed)
+      sb.append(':').append(port);
 
-    resStr = resStr + file;
+    sb.append(file);
 
     if (ref != null)
-      resStr = resStr + "#" + ref;
+      sb.append('#').append(ref);
 
-    return resStr;
+    return sb.toString();
   }
 }

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