Source for gnu.java.net.protocol.jar.Handler

   1: /* gnu.java.net.protocol.jar.Handler - jar protocol handler for java.net
   2:    Copyright (C) 1999, 2002, 2003, 2005 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10:  
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package gnu.java.net.protocol.jar;
  40: 
  41: import gnu.java.net.URLParseError;
  42: 
  43: import java.io.IOException;
  44: import java.net.MalformedURLException;
  45: import java.net.URL;
  46: import java.net.URLConnection;
  47: import java.net.URLStreamHandler;
  48: 
  49: /**
  50:  * @author Kresten Krab Thorup (krab@gnu.org)
  51:  */
  52: public class Handler extends URLStreamHandler
  53: {
  54:   /**
  55:    * A do nothing constructor
  56:    */
  57:   public Handler()
  58:   {
  59:   }
  60: 
  61:   /**
  62:    * This method returs a new JarURLConnection for the specified URL
  63:    *
  64:    * @param url The URL to return a connection for
  65:    *
  66:    * @return The URLConnection
  67:    *
  68:    * @exception IOException If an error occurs
  69:    */
  70:   protected URLConnection openConnection(URL url) throws IOException
  71:   {
  72:     return new Connection(url);
  73:   }
  74: 
  75:   /**
  76:    * This method overrides URLStreamHandler's for parsing url of protocol "jar"
  77:    *
  78:    * @param url The URL object in which to store the results
  79:    * @param url_string The String-ized URL to parse
  80:    * @param start The position in the string to start scanning from
  81:    * @param end The position in the string to stop scanning
  82:    */
  83:   protected void parseURL (URL url, String url_string, int start, int end)
  84:   {
  85:     // This method does not throw an exception or return a value.  Thus our
  86:     // strategy when we encounter an error in parsing is to return without
  87:     // doing anything.
  88:     String file = url.getFile();
  89:     
  90:     if (!file.equals(""))
  91:       { //has context url
  92:     url_string = url_string.substring (start, end);
  93:         if (url_string.startsWith("/"))
  94:           { //url string is an absolute path
  95:             int idx = file.lastIndexOf ("!/");
  96:         
  97:         if (idx < 0)
  98:           throw new URLParseError("no !/ in spec");
  99:         
 100:         file = file.substring (0, idx + 1) + url_string;
 101:           }
 102:         else if (url_string.length() > 0)
 103:           {
 104:             int idx = file.lastIndexOf ("/");
 105:             if (idx == -1) //context path is weird
 106:               file = "/" + url_string; 
 107:             else if (idx == (file.length() - 1))
 108:               //just concatenate two parts
 109:               file = file + url_string;
 110:             else
 111:               // according to Java API Documentation, here is a little different 
 112:               // with URLStreamHandler.parseURL
 113:               // but JDK seems doesn't handle it well
 114:               file = file.substring(0, idx + 1) + url_string;
 115:           }
 116:         
 117:         setURL (url, "jar", url.getHost(), url.getPort(), file, null);
 118:         return;
 119:       }
 120: 
 121:     // Bunches of things should be true.  Make sure.
 122:     if (end < start)
 123:       return;
 124:     if (end - start < 2)
 125:       return;
 126:     if (start > url_string.length())
 127:       return;
 128:     
 129:     // Skip remains of protocol
 130:     url_string = url_string.substring (start, end);
 131: 
 132:     int jar_stop;
 133:     if ((jar_stop = url_string.indexOf("!/")) < 0)
 134:       throw new URLParseError("no !/ in spec");
 135: 
 136:     try
 137:       {
 138:     new URL(url_string.substring (0, jar_stop));
 139:       }
 140:     catch (MalformedURLException e)
 141:       {
 142:     throw new URLParseError("invalid inner URL: " + e.getMessage());
 143:       }
 144:     
 145:     if (!url.getProtocol().equals ("jar") )
 146:       throw new URLParseError("unexpected protocol " + url.getProtocol());
 147:         
 148:     setURL (url, "jar", url.getHost(), url.getPort(), url_string, null);
 149:   }
 150: 
 151:   /**
 152:    * This method converts a Jar URL object into a String.
 153:    *
 154:    * @param url The URL object to convert
 155:    */
 156:   protected String toExternalForm (URL url)
 157:   {
 158:     String file = url.getFile();
 159:     String ref = url.getRef();
 160: 
 161:     // return "jar:" + file;
 162:     // Performance!!: 
 163:     //  Do the concatenation manually to avoid resize StringBuffer's 
 164:     //  internal buffer.  The length of ref is not taken into consideration
 165:     //  as it's a rare path.
 166:     StringBuffer sb = new StringBuffer (file.length() + 5);
 167:     sb.append ("jar:");
 168:     sb.append (file);
 169:     if (ref != null)
 170:       sb.append('#').append(ref);
 171:     return sb.toString();
 172:   }
 173: }