libjava/java/lang/Class.java

   1 // Class.java - Representation of a Java class.
   2
   3 /* Copyright (C) 1998, 1999, 2000  Red Hat, Inc.
   4
   5    This file is part of libgcj.
   6
   7 This software is copyrighted work licensed under the terms of the
   8 Libgcj License.  Please consult the file "LIBGCJ_LICENSE" for
   9 details.  */
  10
  11 package java.lang;
  12 import java.io.Serializable;
  13 import java.io.InputStream;
  14 import java.lang.reflect.*;
  15
  16 /**
  17  * @author Tom Tromey <tromey@cygnus.com>
  18  * @date October 1, 1998
  19  */
  20
  21 /* Written using "Java Class Libraries", 2nd edition, ISBN 0-201-31002-3
  22  * "The Java Language Specification", ISBN 0-201-63451-1
  23  * plus online API docs for JDK 1.2 beta from http://www.javasoft.com.
  24  * plus gcj compiler sources (to determine object layout)
  25  * Status:  Sufficient for our purposes, but some methods missing
  26  * and some not implemented.
  27  */
  28
  29 public final class Class implements Serializable
  30 {
  31   public static native Class forName (String className)
  32     throws ClassNotFoundException;
  33   public native Class[] getClasses ();
  34   public native ClassLoader getClassLoader ();
  35   public native Class getComponentType ();
  36
  37   public native Constructor getConstructor (Class[] parameterTypes)
  38     throws NoSuchMethodException, SecurityException;
  39
  40   // This is used to implement getConstructors and
  41   // getDeclaredConstructors.
  42   private native Constructor[] _getConstructors (boolean declared)
  43     throws SecurityException;
  44
  45   public Constructor[] getConstructors () throws SecurityException
  46   {
  47     return _getConstructors (false);
  48   }
  49
  50   public native Constructor getDeclaredConstructor (Class[] parameterTypes)
  51     throws NoSuchMethodException, SecurityException;
  52
  53   public native Class[] getDeclaredClasses () throws SecurityException;
  54
  55   public Constructor[] getDeclaredConstructors () throws SecurityException
  56   {
  57     return _getConstructors (true);
  58   }
  59
  60   public native Field getDeclaredField (String fieldName)
  61     throws NoSuchFieldException, SecurityException;
  62   public native Field[] getDeclaredFields () throws SecurityException;
  63   public native Method getDeclaredMethod (String methodName,
  64                                           Class[] parameterTypes)
  65     throws NoSuchMethodException, SecurityException;
  66   public native Method[] getDeclaredMethods () throws SecurityException;
  67
  68   // This is marked as unimplemented in the JCL book.
  69   public native Class getDeclaringClass ();
  70
  71   private native Field getField (String fieldName, int hash)
  72     throws NoSuchFieldException, SecurityException;
  73
  74   public Field getField (String fieldName)
  75     throws NoSuchFieldException, SecurityException
  76   {
  77     SecurityManager s = System.getSecurityManager();
  78     if (s != null)
  79       s.checkMemberAccess (this, java.lang.reflect.Member.DECLARED);
  80     Field fld = getField(fieldName, fieldName.hashCode());
  81     if (fld == null)
  82       throw new NoSuchFieldException(fieldName);
  83     return fld;
  84   }
  85
  86   private native Field[] _getFields (Field[] result, int offset);
  87   public native Field[] getFields () throws SecurityException;
  88
  89   public native Class[] getInterfaces ();
  90
  91   private final native void getSignature (StringBuffer buffer);
  92   private static final native String getSignature (Class[] parameterTypes,
  93                                                    boolean is_construtor);
  94
  95   public native Method getMethod (String methodName, Class[] parameterTypes)
  96     throws NoSuchMethodException, SecurityException;
  97   private native int _getMethods (Method[] result, int offset);
  98   public native Method[] getMethods () throws SecurityException;
  99
 100   public native int getModifiers ();
 101   public native String getName ();
 102
 103   public java.net.URL getResource (String resourceName)
 104   {
 105     String name = resourcePath (resourceName);
 106     ClassLoader loader = getClassLoader ();
 107     if (loader == null)
 108       return ClassLoader.getSystemResource (name);
 109     else
 110       return loader.getResource (name);
 111   }
 112
 113   public java.io.InputStream getResourceAsStream (String resourceName)
 114   {
 115     String name = resourcePath (resourceName);
 116     ClassLoader loader = getClassLoader ();
 117     if (loader == null)
 118       return ClassLoader.getSystemResourceAsStream (name);
 119     else
 120       return loader.getResourceAsStream (name);
 121   }
 122
 123   private String resourcePath (String resourceName)
 124   {
 125     if (resourceName.startsWith ("/"))
 126       return resourceName.substring (1);
 127
 128     Class c = this;
 129     while (c.isArray ())
 130       c = c.getComponentType ();
 131
 132     String packageName = c.getName ().replace ('.', '/');
 133     int end = packageName.lastIndexOf ('/');
 134     if (end == -1)
 135       return resourceName;
 136     else
 137       return packageName.substring (0, end+1) + resourceName;
 138   }
 139
 140   // FIXME: implement.  Requires java.security.
 141   public Object[] getSigners ()
 142   {
 143     return null;
 144   }
 145
 146   public native Class getSuperclass ();
 147   public native boolean isArray ();
 148   public native boolean isAssignableFrom (Class cls);
 149   public native boolean isInstance (Object obj);
 150   public native boolean isInterface ();
 151   public native boolean isPrimitive ();
 152   public native Object newInstance ()
 153     throws InstantiationException, IllegalAccessException;
 154
 155   public String toString ()
 156   {
 157     if (isPrimitive ())
 158       return getName ();
 159     return (isInterface () ? "interface " : "class ") + getName ();
 160   }
 161
 162   // Don't allow new classes to be made.
 163   private Class ()
 164   {
 165   }
 166
 167   // Do a security check.
 168   private void checkMemberAccess (int flags)
 169   {
 170     SecurityManager sm = System.getSecurityManager();
 171     if (sm != null)
 172       sm.checkMemberAccess(this, flags);
 173   }
 174
 175   // FIXME: this method exists only because we cannot catch Java
 176   // exceptions from C++ code.  This is a helper for initializeClass.
 177   private Throwable hackTrampoline (int what, Throwable old_exception)
 178     {
 179       Throwable new_val = null;
 180       try
 181         {
 182           if (what == 0)
 183             initializeClass ();
 184           else if (what == 1)
 185             hackRunInitializers ();
 186           else if (what == 2)
 187             new_val = new ExceptionInInitializerError (old_exception);
 188         }
 189       catch (Throwable t)
 190         {
 191           new_val = t;
 192         }
 193       return new_val;
 194     }
 195
 196   // FIXME: this is a hack to let us run the class initializers.  We
 197   // could do it inline in initializeClass() if we could catch Java
 198   // exceptions from C++.
 199   private native void hackRunInitializers ();
 200
 201   // Initialize the class.
 202   private native void initializeClass ();
 203
 204   // finalization
 205   protected native void finalize ();
 206 }