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ClassLoader.java (getSystemClassLoader, [...]): Add javadoc from classpath.

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2002-08-07  Bryce McKinlay  <bryce@waitaki.otago.ac.nz>

	* java/lang/ClassLoader.java (getSystemClassLoader, findClass,
	defineClass, setSigners, getSystemResource, getSystemResourceAsStream,
	findResource, getResources, findResources): Add javadoc from classpath.
	(getSystemResources): Implemented.

From-SVN: r56092
This commit is contained in:
Bryce McKinlay 2002-08-07 05:28:24 +00:00 committed by Bryce McKinlay
parent af34e51e35
commit 6ee4402c61
2 changed files with 200 additions and 22 deletions
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7
libjava/ChangeLog
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@ -1,3 +1,10 @@
2002-08-07 Bryce McKinlay <bryce@waitaki.otago.ac.nz>
* java/lang/ClassLoader.java (getSystemClassLoader, findClass,
defineClass, setSigners, getSystemResource, getSystemResourceAsStream,
findResource, getResources, findResources): Add javadoc from classpath.
(getSystemResources): Implemented.
2002-08-01 Mark Wielaard <mark@klomp.org>
Revert patch that breaks libgcj shared library on powerpc:

215
libjava/java/lang/ClassLoader.java
View File

@ -82,6 +82,31 @@ public abstract class ClassLoader
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;
@ -174,14 +199,48 @@ public abstract class ClassLoader
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
{
@ -234,6 +293,25 @@ public abstract class ClassLoader
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
{
@ -504,11 +582,19 @@ public abstract class ClassLoader
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.
*/
}
/**
@ -521,14 +607,45 @@ public abstract class ClassLoader
*/
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
@ -541,13 +658,17 @@ public abstract class ClassLoader
*/
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;
}
}
/**
@ -582,13 +703,47 @@ public abstract class ClassLoader
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
@ -611,10 +766,26 @@ public abstract class ClassLoader
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);
}
/**