libjava/gnu/gcj/runtime/VMClassLoader.java

   1 /* Copyright (C) 1999, 2001, 2002, 2003  Free Software Foundation
   2
   3    This file is part of libgcj.
   4
   5 This software is copyrighted work licensed under the terms of the
   6 Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
   7 details.  */
   8
   9 /* Author: Kresten Krab Thorup <krab@gnu.org>  */
  10
  11 package gnu.gcj.runtime;
  12
  13 import java.io.*;
  14 import java.util.StringTokenizer;
  15 import java.util.HashSet;
  16 import java.net.URL;
  17
  18 public final class VMClassLoader extends java.net.URLClassLoader
  19 {
  20   private VMClassLoader ()
  21   {
  22     super (init());
  23     String p
  24       = System.getProperty ("gnu.gcj.runtime.VMClassLoader.library_control",
  25                             "");
  26     if ("never".equals(p))
  27       lib_control = LIB_NEVER;
  28     else if ("cache".equals(p))
  29       lib_control = LIB_CACHE;
  30     else if ("full".equals(p))
  31       {
  32         // In case we ever want to change the default.
  33         lib_control = LIB_FULL;
  34       }
  35     else
  36       lib_control = LIB_FULL;
  37   }
  38
  39   private static URL[] init()
  40   {
  41     StringTokenizer st
  42         = new StringTokenizer (System.getProperty ("java.class.path", "."),
  43                                System.getProperty ("path.separator", ":"));
  44
  45     java.util.Vector p = new java.util.Vector();
  46     while (st.hasMoreElements ())
  47       {
  48         String e = st.nextToken ();
  49         try
  50           {
  51             if (!e.endsWith (File.separator) && new File (e).isDirectory ())
  52               p.addElement (new URL("file", "", -1, e + File.separator));
  53             else
  54               p.addElement (new URL("file", "", -1, e));
  55           }
  56         catch (java.net.MalformedURLException x)
  57           {
  58             /* Ignore this path element */
  59           }
  60       }
  61     // Add core:/ to the end of the java.class.path so any resources
  62     // compiled into this executable may be found.
  63     try
  64       {
  65         p.addElement (new URL("core", "", -1, "/"));
  66       }
  67     catch (java.net.MalformedURLException x)
  68       {
  69         // This should never happen.
  70       }
  71
  72     URL[] urls = new URL[p.size()];
  73     p.copyInto (urls);
  74     return urls;
  75   }
  76
  77   /** This is overridden to search the internal hash table, which
  78    * will only search existing linked-in classes.   This will make
  79    * the default implementation of loadClass (in ClassLoader) work right.
  80    * The implementation of this method is in java/lang/natClassLoader.cc.
  81    */
  82   protected native Class findClass(String name)
  83     throws java.lang.ClassNotFoundException;
  84
  85   // This keeps track of shared libraries we've already tried to load.
  86   private HashSet tried_libraries = new HashSet();
  87
  88   // Holds one of the LIB_* constants; used to determine how shared
  89   // library loads are done.
  90   private int lib_control;
  91
  92   // The only VMClassLoader that can exist.
  93   static VMClassLoader instance = new VMClassLoader();
  94
  95   private static final int LIB_FULL = 0;
  96   private static final int LIB_CACHE = 1;
  97   private static final int LIB_NEVER = 2;
  98 }