return parent;
}
+ /**
+ * Returns the system classloader. The system classloader (also called
+ * the application classloader) is the classloader that was used to
+ * load the application classes on the classpath (given by the system
+ * property <code>java.class.path</code>. This is set as the context
+ * class loader for a thread. The system property
+ * <code>java.system.class.loader</code>, if defined, is taken to be the
+ * name of the class to use as the system class loader, which must have
+ * a public constructor which takes a ClassLoader as a parent; otherwise this
+ * uses gnu.java.lang.SystemClassLoader.
+ *
+ * <p>Note that this is different from the bootstrap classloader that
+ * actually loads all the real "system" classes (the bootstrap classloader
+ * is the parent of the returned system classloader).
+ *
+ * <p>A security check will be performed for
+ * <code>RuntimePermission("getClassLoader")</code> if the calling class
+ * is not a parent of the system class loader.
+ *
+ * @return the system class loader
+ * @throws SecurityException if the security check fails
+ * @throws IllegalStateException if this is called recursively
+ * @throws Error if <code>java.system.class.loader</code> fails to load
+ * @since 1.2
+ */
public static ClassLoader getSystemClassLoader ()
{
return gnu.gcj.runtime.VMClassLoader.instance;
return c;
}
- /** Find a class. This should be overridden by subclasses; the
- * default implementation throws ClassNotFoundException.
+ /**
+ * Called for every class name that is needed but has not yet been
+ * defined by this classloader or one of its parents. It is called by
+ * <code>loadClass()</code> after both <code>findLoadedClass()</code> and
+ * <code>parent.loadClass()</code> couldn't provide the requested class.
*
- * @param name Name of the class to find.
- * @return The class found.
- * @exception java.lang.ClassNotFoundException
+ * <p>The default implementation throws a
+ * <code>ClassNotFoundException</code>. Subclasses should override this
+ * method. An implementation of this method in a subclass should get the
+ * class bytes of the class (if it can find them), if the package of the
+ * requested class doesn't exist it should define the package and finally
+ * it should call define the actual class. It does not have to resolve the
+ * class. It should look something like the following:<br>
+ *
+ * <pre>
+ * // Get the bytes that describe the requested class
+ * byte[] classBytes = classLoaderSpecificWayToFindClassBytes(name);
+ * // Get the package name
+ * int lastDot = name.lastIndexOf('.');
+ * if (lastDot != -1)
+ * {
+ * String packageName = name.substring(0, lastDot);
+ * // Look if the package already exists
+ * if (getPackage(pkg) == null)
+ * {
+ * // define the package
+ * definePackage(packageName, ...);
+ * }
+ * }
+ * // Define and return the class
+ * return defineClass(name, classBytes, 0, classBytes.length);
+ * </pre>
+ *
+ * <p><code>loadClass()</code> makes sure that the <code>Class</code>
+ * returned by <code>findClass()</code> will later be returned by
+ * <code>findLoadedClass()</code> when the same class name is requested.
+ *
+ * @param name class name to find (including the package name)
+ * @return the requested Class
+ * @throws ClassNotFoundException when the class can not be found
* @since 1.2
- */
+ */
protected Class findClass (String name)
throws ClassNotFoundException
{
return defineClass (null, data, off, len, defaultProtectionDomain);
}
+ /**
+ * Helper to define a class using a string of bytes without a
+ * ProtectionDomain. Subclasses should call this method from their
+ * <code>findClass()</code> implementation. The name should use '.'
+ * separators, and discard the trailing ".class". The default protection
+ * domain has the permissions of
+ * <code>Policy.getPolicy().getPermissions(new CodeSource(null, null))<code>.
+ *
+ * @param name the name to give the class, or null if unknown
+ * @param data the data representing the classfile, in classfile format
+ * @param offset the offset into the data where the classfile starts
+ * @param len the length of the classfile data in the array
+ * @return the class that was defined
+ * @throws ClassFormatError if data is not in proper classfile format
+ * @throws IndexOutOfBoundsException if offset or len is negative, or
+ * offset + len exceeds data
+ * @throws SecurityException if name starts with "java."
+ * @since 1.1
+ */
protected final Class defineClass(String name, byte[] data, int off, int len)
throws ClassFormatError
{
return gnu.gcj.runtime.VMClassLoader.instance.loadClass (name);
}
- /*
- * Does currently nothing. FIXME.
- */
- protected final void setSigners(Class claz, Object[] signers) {
- /* claz.setSigners (signers); */
+ /**
+ * Helper to set the signers of a class. This should be called after
+ * defining the class.
+ *
+ * @param c the Class to set signers of
+ * @param signers the signers to set
+ * @since 1.1
+ */
+ protected final void setSigners(Class c, Object[] signers)
+ {
+ /*
+ * Does currently nothing. FIXME.
+ */
}
/**
*/
protected final native Class findLoadedClass(String name);
+
+ /**
+ * Get a resource using the system classloader.
+ *
+ * @param name the name of the resource relative to the system classloader
+ * @return an input stream for the resource, or null
+ * @since 1.1
+ */
public static InputStream getSystemResourceAsStream(String name) {
return getSystemClassLoader().getResourceAsStream (name);
}
+ /**
+ * Get the URL to a resource using the system classloader.
+ *
+ * @param name the name of the resource relative to the system classloader
+ * @return the URL to the resource
+ * @since 1.1
+ */
public static URL getSystemResource(String name) {
return getSystemClassLoader().getResource (name);
}
+ /**
+ * Get an Enumeration of URLs to resources with a given name using the
+ * the system classloader. The enumeration firsts lists the resources with
+ * the given name that can be found by the bootstrap classloader followed
+ * by the resources with the given name that can be found on the classpath.
+ *
+ * @param name the name of the resource relative to the system classloader
+ * @return an Enumeration of URLs to the resources
+ * @throws IOException if I/O errors occur in the process
+ * @since 1.2
+ */
+ public static Enumeration getSystemResources(String name) throws IOException
+ {
+ return getSystemClassLoader().getResources(name);
+ }
+
/**
* Return an InputStream representing the resource name.
* This is essentially like
*/
public InputStream getResourceAsStream(String name)
{
- try {
- URL res = getResource (name);
- if (res == null) return null;
- return res.openStream ();
- } catch (java.io.IOException x) {
- return null;
- }
+ try
+ {
+ URL res = getResource (name);
+ if (res == null)
+ return null;
+ return res.openStream ();
+ }
+ catch (java.io.IOException x)
+ {
+ return null;
+ }
}
/**
return findResource (name);
}
+ /**
+ * Called whenever a resource is needed that could not be provided by
+ * one of the parents of this classloader. It is called by
+ * <code>getResource()</code> after <code>parent.getResource()</code>
+ * couldn't provide the requested resource.
+ *
+ * <p>The default implementation always returns null. Subclasses should
+ * override this method when they can provide a way to return a URL
+ * to a named resource.
+ *
+ * @param name the name of the resource to be found
+ * @return a URL to the named resource or null when not found
+ * @since 1.2
+ */
protected URL findResource (String name)
{
// Default to returning null. Derived classes implement this.
return null;
}
- public final Enumeration getResources (String name) throws IOException
+ /**
+ * Returns an Enumeration of all resources with a given name that can
+ * be found by this classloader and its parents. Certain classloaders
+ * (such as the URLClassLoader when given multiple jar files) can have
+ * multiple resources with the same name that come from multiple locations.
+ * It can also occur that a parent classloader offers a resource with a
+ * certain name and the child classloader also offers a resource with that
+ * same name. <code>getResource() only offers the first resource (of the
+ * parent) with a given name. This method lists all resources with the
+ * same name. The name should use '/' as path separators.
+ *
+ * <p>The Enumeration is created by first calling <code>getResources()</code>
+ * on the parent classloader and then calling <code>findResources()</code>
+ * on this classloader.
+ *
+ * @param name the resource name
+ * @return an enumaration of all resources found
+ * @throws IOException if I/O errors occur in the process
+ * @since 1.2
+ */
+ public final Enumeration getResources(String name) throws IOException
{
// The rules say search the parent class if non-null,
// otherwise search the built-in class loader (assumed to be
return findResources (name);
}
- protected Enumeration findResources (String name) throws IOException
+ /**
+ * Called whenever all locations of a named resource are needed.
+ * It is called by <code>getResources()</code> after it has called
+ * <code>parent.getResources()</code>. The results are combined by
+ * the <code>getResources()</code> method.
+ *
+ * <p>The default implementation always returns an empty Enumeration.
+ * Subclasses should override it when they can provide an Enumeration of
+ * URLs (possibly just one element) to the named resource.
+ * The first URL of the Enumeration should be the same as the one
+ * returned by <code>findResource</code>.
+ *
+ * @param name the name of the resource to be found
+ * @return a possibly empty Enumeration of URLs to the named resource
+ * @throws IOException if I/O errors occur in the process
+ * @since 1.2
+ */
+ protected Enumeration findResources(String name) throws IOException
{
- // Default to returning null. Derived classes implement this.
- return null;
+ return Collections.enumeration(Collections.EMPTY_LIST);
}
/**
projects / gcc.git / commitdiff