Source for gnu.java.net.loader.Resource

   1: /* Resource.java -- a resource for URLLoader
   2:    Copyright (C) 2006 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.loader;
  40: 
  41: 
  42: import java.io.IOException;
  43: import java.io.InputStream;
  44: import java.net.URL;
  45: import java.security.CodeSource;
  46: import java.security.cert.Certificate;
  47: 
  48: /**
  49:  * A <code>Resource</code> represents a resource in some
  50:  * <code>URLLoader</code>. It also contains all information (e.g.,
  51:  * <code>URL</code>, <code>CodeSource</code>, <code>Manifest</code> and
  52:  * <code>InputStream</code>) that is necessary for loading resources
  53:  * and creating classes from a <code>URL</code>.
  54:  */
  55: public abstract class Resource
  56: {
  57:   final URLLoader loader;
  58: 
  59:   public Resource(URLLoader loader)
  60:   {
  61:     this.loader = loader;
  62:   }
  63: 
  64:   /**
  65:    * Returns the non-null <code>CodeSource</code> associated with
  66:    * this resource.
  67:    */
  68:   public CodeSource getCodeSource()
  69:   {
  70:     Certificate[] certs = getCertificates();
  71:     if (certs == null)
  72:       return loader.noCertCodeSource;
  73:     else
  74:       return new CodeSource(loader.baseURL, certs);
  75:   }
  76: 
  77:   /**
  78:    * Returns <code>Certificates</code> associated with this
  79:    * resource, or null when there are none.
  80:    */
  81:   public Certificate[] getCertificates()
  82:   {
  83:     return null;
  84:   }
  85: 
  86:   /**
  87:    * Return the URLLoader for this resource.
  88:    */
  89:   public final URLLoader getLoader()
  90:   {
  91:     return loader;
  92:   }
  93: 
  94:   /**
  95:    * Return a <code>URL</code> that can be used to access this resource.
  96:    */
  97:   public abstract URL getURL();
  98: 
  99:   /**
 100:    * Returns the size of this <code>Resource</code> in bytes or
 101:    * <code>-1</code> when unknown.
 102:    */
 103:   public abstract int getLength();
 104: 
 105:   /**
 106:    * Returns the non-null <code>InputStream</code> through which
 107:    * this resource can be loaded.
 108:    */
 109:   public abstract InputStream getInputStream() throws IOException;
 110: }