/*
* @(#)ClassLoader.java 1.162 02/03/19
*
* Copyright 2002 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
import java.io.InputStream;
import java.io.IOException;
import java.io.StringWriter;
import java.io.PrintWriter;
import java.io.File;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.util.Hashtable;
import java.util.Enumeration;
import java.util.Vector;
import java.util.Stack;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.NoSuchElementException;
import java.util.Set;
import java.util.jar.Manifest;
import java.net.URL;
import java.net.MalformedURLException;
import java.security.AccessController;
import java.security.AccessControlContext;
import java.security.PrivilegedAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.security.ProtectionDomain;
import java.security.Permissions;
import java.security.CodeSource;
import java.security.Policy;
import sun.misc.URLClassPath;
import sun.misc.Resource;
import sun.misc.CompoundEnumeration;
import sun.misc.ClassFileTransformer;
//import sun.misc.Launcher;
import sun.reflect.Reflection;
import sun.security.action.GetPropertyAction;
/**
* A class loader is an object that is responsible for loading
* classes. The class <code>ClassLoader</code> is an abstract class.
* Given the name of a class, a class loader should attempt to locate
* or generate data that constitutes a definition for the class. A
* typical strategy is to transform the name into a file
* name and then read a "class file" of that name from a file system.
* <p>
* Every <code>Class</code> object contains a
* {@link Class#getClassLoader() reference} to the
* <code>ClassLoader</code> that defined it.
* <p>
* Class objects for array classes are not created by class loaders, but
* are created automatically as required by the Java runtime. The class
* loader for an array class, as returned by {@link Class#getClassLoader()}
* is the same as the class loader for its element type; if the element
* type is a primitive type, then the array class has no class loader.
* <p>
* Applications implement subclasses of <code>ClassLoader</code> in
* order to extend the manner in which the Java virtual machine
* dynamically loads classes.
* <p>
* Class loaders may typically be used by security managers to
* indicate security domains.
* <p>
* The <code>ClassLoader</code> class uses a delegation model to
* search for classes and resources. Each instance of
* <code>ClassLoader</code> has an associated parent class loader.
* When called upon to find a class or resource, a
* <code>ClassLoader</code> instance will delegate the search for
* the class or resource to its parent class loader before
* attempting to find the class or resource itself. The virtual
* machine's built-in class loader, called the bootstrap class loader,
* does not itself have a parent but may serve as the parent of a
* <code>ClassLoader</code> instance.
* <p>
* Normally, the Java virtual machine loads classes from the local
* file system in a platform-dependent manner. For example, on UNIX
* systems, the virtual machine loads classes from the directory
* defined by the <code>CLASSPATH</code> environment variable.
* <p>
* However, some classes may not originate from a file; they may
* originate from other sources, such as the network, or they could
* be constructed by an application. The method
* <code>defineClass</code> converts an array of bytes into an
* instance of class <code>Class</code>. Instances of this newly
* defined class can be created using the <code>newInstance</code>
* method in class <code>Class</code>.
* <p>
* The methods and constructors of objects created by a class loader
* may reference other classes. To determine the class(es) referred
* to, the Java virtual machine calls the <code>loadClass</code>
* method of the class loader that originally created the class.
* <p>
* For example, an application could create a network class loader
* to download class files from a server. Sample code might look like:
* <blockquote><pre>
* ClassLoader loader = new NetworkClassLoader(host, port);
* Object main = loader.loadClass("Main", true).newInstance();
* . . .
* </pre></blockquote>
* <p>
* The network class loader subclass must define the methods
* <code>findClass</code> and <code>loadClassData</code>
* to load a class from the network. Once it
* has downloaded the bytes that make up the class, it should use the
* method <code>defineClass</code> to create a class instance. A
* sample implementation is:
* <p><hr><blockquote><pre>
* class NetworkClassLoader extends ClassLoader {
* String host;
* int port;
*
* public Class findClass(String name) {
* byte[] b = loadClassData(name);
* return defineClass(name, b, 0, b.length);
* }
*
* private byte[] loadClassData(String name) {
* // load the class data from the connection
* . . .
* }
* }
* </pre></blockquote><hr>
*
* @version 1.162, 03/19/02
* @see java.lang.Class
* @see java.lang.Class#newInstance()
* @see java.lang.ClassLoader#defineClass(byte[], int, int)
* @see java.lang.ClassLoader#loadClass(java.lang.String, boolean)
* @see java.lang.ClassLoader#resolveClass(java.lang.Class)
* @since JDK1.0
*/
public abstract class ClassLoader {
private static native void registerNatives();
static {
registerNatives();
}
/*
* If initialization succeed this is set to true and security checks will
* succeed. Otherwise the object is not initialized and the object is
* useless.
*/
private boolean initialized = false;
/*
* The parent class loader for delegation.
*/
private ClassLoader parent;
/*
* Hashtable that maps packages to certs
*/
private Hashtable package2certs = new Hashtable(11);
/*
* shared among all packages with unsigned classes
*/
java.security.cert.Certificate[] nocerts;
/*
* The classes loaded by this class loader. The only purpose of this
* table is to keep the classes from being GC'ed until the loader
* is GC'ed.
*/
private Vector classes = new Vector();
/*
* The initiating protection domains for all classes
* loaded by this loader.
*/
private Set domains = new HashSet();
/*
* Called by the VM to record every loaded class with this loader.
*/
void addClass(Class c) {
classes.addElement(c);
}
/*
* The packages defined in this class loader. Each package name is
* mapped to its corresponding Package object.
*/
private HashMap packages = new HashMap();
/**
* Creates a new class loader using the specified parent class loader
* for delegation.
* <p>
* If there is a security manager, its <code>checkCreateClassLoader</code>
* method is called. This may result in a security exception.
*
* @param parent the parent class loader
*
* @throws SecurityException if a security manager exists and its
* <code>checkCreateClassLoader</code> method doesn't allow creation of a
* new class loader.
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkCreateClassLoader()
* @since 1.2
*/
protected ClassLoader(ClassLoader parent) {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkCreateClassLoader();
}
this.parent = parent;
initialized = true;
}
/**
* Creates a new class loader using the <code>ClassLoader</code>
* returned by the method <code>getSystemClassLoader()</code> as the
* parent class loader.
* <p>
* If there is a security manager, its <code>checkCreateClassLoader</code>
* method is called. This may result in a security exception.
*
* @throws SecurityException
* if a security manager exists and its <code>checkCreateClassLoader</code>
* method doesn't allow creation of a new class loader.
*
* @see java.lang.SecurityException
* @see java.lang.SecurityManager#checkCreateClassLoader()
*/
protected ClassLoader() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkCreateClassLoader();
}
this.parent = getSystemClassLoader();
initialized = true;
}
/**
* Loads the class with the specified name. This method searches for
* classes in the same manner as the {@link #loadClass(String, boolean)}
* method. It is called by the Java virtual machine to resolve class
* references. Calling this method is equivalent to calling
* <code>loadClass(name, false)</code>.
*
* @param name the name of the class
* @return the resulting <code>Class</code> object
* @exception ClassNotFoundException if the class was not found
*/
public Class loadClass(String name) throws ClassNotFoundException
{
return loadClass(name, false);
}
/**
* Loads the class with the specified name. The default implementation of
* this method searches for classes in the following order:<p>
*
* <ol>
* <li> Call {@link #findLoadedClass(String)} to check if the class has
* already been loaded. <p>
* <li> Call the <code>loadClass</code> method on the parent class
* loader. If the parent is <code>null</code> the class loader
* built-in to the virtual machine is used, instead. <p>
* <li> Call the {@link #findClass(String)} method to find the class. <p>
* </ol>
*
* If the class was found using the above steps, and the
* <code>resolve</code> flag is true, this method will then call the
* {@link #resolveClass(Class)} method on the resulting class object.
* <p>
* From the Java 2 SDK, v1.2, subclasses of ClassLoader are
* encouraged to override
* {@link #findClass(String)}, rather than this method.<p>
*
* @param name the name of the class
* @param resolve if <code>true</code> then resolve the class
* @return the resulting <code>Class</code> object
* @exception ClassNotFoundException if the class could not be found
*/
protected synchronized Class loadClass(String name, boolean resolve)
throws ClassNotFoundException
{
// First, check if the class has already been loaded
Class c = findLoadedClass(name);
if (c == null) {
try {
if (parent != null) {
c = parent.loadClass(name, false);
} else {
c = findBootstrapClass0(name);
}
} catch (ClassNotFoundException e) {
// If still not found, then call findClass in order
// to find the class.
c = findClass(name);
}
}
if (resolve) {
resolveClass(c);
}
return c;
}
/*
* This method is called by the virtual machine to load
* a class.
*/
private synchronized Class loadClassInternal(String name)
throws ClassNotFoundException {
return loadClass(name);
}
private void checkPackageAccess(Class cls, ProtectionDomain pd) {
final SecurityManager sm = System.getSecurityManager();
if (sm != null) {
final String name = cls.getName();
final int i = name.lastIndexOf('.');
if (i != -1) {
AccessController.doPrivileged(new PrivilegedAction() {
public Object run() {
sm.checkPackageAccess(name.substring(0, i));
return null;
}
}, new AccessControlContext(new ProtectionDomain[] {pd}));
}
}
domains.add(pd);
}
/**
* Finds the specified class. This method should be overridden
* by class loader implementations that follow the new delegation model
* for loading classes, and will be called by the <code>loadClass</code>
* method after checking the parent class loader for the requested class.
* The default implementation throws <code>ClassNotFoundException</code>.
*
* @param name the name of the class
* @return the resulting <code>Class</code> object
* @exception ClassNotFoundException if the class could not be found
* @since 1.2
*/
protected Class findClass(String name) throws ClassNotFoundException {
throw new ClassNotFoundException(name);
}
/**
* Converts an array of bytes into an instance of class
* <code>Class</code>. Before the Class can be used it must be
* resolved. This method is deprecated in favor of the version
* that takes the class name as its first argument, and is more
* secure.
*
* @param b the bytes that make up the class data. The bytes in
* positions <code>off</code> through <code>off+len-1</code>
* should have the format of a valid class file as defined
* by the
* <a href="http://java.sun.com/docs/books/vmspec/">Java
* Virtual Machine Specification</a>.
* @param off the start offset in <code>b</code> of the class data
* @param len the length of the class data
* @return the <code>Class</code> object that was created from the
* specified class data
* @exception ClassFormatError if the data did not contain a valid class
* @exception IndexOutOfBoundsException if either <code>off</code> or
* <code>len</code> is negative, or if
* <code>off+len</code> is greater than <code>b.length</code>.
* @see ClassLoader#loadClass(java.lang.String, boolean)
* @see ClassLoader#resolveClass(java.lang.Class)
* @deprecated Replaced by defineClass(java.lang.String, byte[], int, int)
*/
protected final Class defineClass(byte[] b, int off, int len)
throws ClassFormatError
{
return defineClass(null, b, off, len, null);
}
/**
* Converts an array of bytes into an instance of class <code>Class</code>.
* Before the Class can be used it must be resolved.
* <p>
* This method assigns a default <code>ProtectionDomain</code> to
* the newly defined class. The <code>ProtectionDomain</code>
* contains the set of permissions granted when
* a call to <code>Policy.getPolicy().getPermissions()</code> is made with
* a code source of <code>null,null</code>. The default domain is
* created on the first invocation of <code>defineClass</code>, and
* re-used on subsequent calls.
* <p>
* To assign a specific <code>ProtectionDomain</code> to the class,
* use the <code>defineClass</code> method that takes a
* <code>ProtectionDomain</code> as one of its arguments.
*
* @param name the expected name of the class, or <code>null</code>
* if not known, using '.' and not '/' as the separator
* and without a trailing ".class" suffix.
* @param b the bytes that make up the class data. The bytes in
* positions <code>off</code> through <code>off+len-1</code>
* should have the format of a valid class file as defined
* by the
* <a href="http://java.sun.com/docs/books/vmspec/">Java
* Virtual Machine Specification</a>.
* @param off the start offset in <code>b</code> of the class data
* @param len the length of the class data
* @return the <code>Class</code> object that was created from the
* specified class data
* @exception ClassFormatError if the data did not contain a valid class
* @exception IndexOutOfBoundsException if either <code>off</code> or
* <code>len</code> is negative, or if
* <code>off+len</code> is greater than <code>b.length</code>.
* @exception SecurityException if an attempt is made to add this class
* to a package that contains classes that were signed by
* a different set of certificates than this class (which
* is unsigned), or if the class name begins with "java.".
*
* @see ClassLoader#loadClass(java.lang.String, boolean)
* @see ClassLoader#resolveClass(java.lang.Class)
* @see java.security.ProtectionDomain
* @see java.security.Policy
* @see java.security.CodeSource
* @see java.security.SecureClassLoader
* @since JDK1.1
*/
protected final Class defineClass(String name, byte[] b, int off, int len)
throws ClassFormatError
{
return defineClass(name, b, off, len, null);
}
/**
* Converts an array of bytes into an instance of class Class,
* with an optional ProtectionDomain. If the domain is <code>null</code>,
* then a default domain will be assigned to the class as specified
* in the documentation for {@link #defineClass(String,byte[],int,int)}.
* Before the class can be used it must be resolved.
*
* <p>The first class defined in a package determines the exact set of
* certificates that all subsequent classes defined in that package must
* contain. The set of certificates for a class is obtained from the
* <code>CodeSource</code> within the <code>ProtectionDomain</code> of
* the class. Any classes added to that package must contain
* the same set of certificates or a <code>SecurityException</code>
* will be thrown. Note that if the <code>name</code> argument is
* null, this check is not performed. You should always pass in the
* name of the class you are defining as well as the bytes. This
* ensures that the class you are defining is indeed the class
* you think it is.
*
* <p>The specified class name cannot begin with "java.", since all
* classes in the java.* packages can only be defined by the bootstrap
* class loader. If the name parameter is not <TT>null</TT>, it
* must be equal to the name of the class specified by the byte
* array b, otherwise a <TT>ClassFormatError</TT> is raised.
*
* @param name the expected name of the class, or <code>null</code>
* if not known, using '.' and not '/' as the separator
* and without a trailing ".class" suffix.
* @param b the bytes that make up the class data. The bytes in
* positions <code>off</code> through <code>off+len-1</code>
* should have the format of a valid class file as defined
* by the
* <a href="http://java.sun.com/docs/books/vmspec/">Java
* Virtual Machine Specification</a>.
* @param off the start offset in <code>b</code> of the class data
* @param len the length of the class data
* @param protectionDomain the ProtectionDomain of the class
* @return the <code>Class</code> object created from the data,
* and optional ProtectionDomain.
* @exception ClassFormatError if the data did not contain a valid class
* @exception IndexOutOfBoundsException if either <code>off</code> or
* <code>len</code> is negative, or if
* <code>off+len</code> is greater than <code>b.length</code>.
* @exception SecurityException if an attempt is made to add this class
* to a package that contains classes that were signed by
* a different set of certificates than this class, or if
* the class name begins with "java.".
*/
protected final Class defineClass(String name, byte[] b, int off, int len,
ProtectionDomain protectionDomain)
throws ClassFormatError
{
check();
if ((name != null) && name.startsWith("java.")) {
throw new SecurityException("Prohibited package name: " +
name.substring(0, name.lastIndexOf('.')));
}
if (protectionDomain == null) {
protectionDomain = getDefaultDomain();
}
if (name != null)
checkCerts(name, protectionDomain.getCodeSource());
Class c = null;
try
{
c = defineClass0(name, b, off, len, protectionDomain);
}
catch (ClassFormatError cfe)
{
// Class format error - try to transform the bytecode and
// define the class again
//
Object[] transformers = ClassFileTransformer.getTransformers();
for (int i=0; transformers != null && i < transformers.length; i++)
{
try
{
// Transform byte code using transformer
byte[] tb = ((ClassFileTransformer) transformers[i]).transform(b, off, len);
c = defineClass0(name, tb, 0, tb.length, protectionDomain);
break;
}
catch (ClassFormatError cfe2)
{
// If ClassFormatError occurs, try next transformer
}
}
// Rethrow original ClassFormatError if unable to transform
// bytecode to well-formed
//
if (c == null)
throw cfe;
}
if (protectionDomain.getCodeSource() != null) {
java.security.cert.Certificate certs[] =
protectionDomain.getCodeSource().getCertificates();
if (certs != null)
setSigners(c, certs);
}
return c;
}
private synchronized void checkCerts(String name, CodeSource cs)
{
int i = name.lastIndexOf('.');
String pname = (i == -1) ? "" : name.substring(0,i);
java.security.cert.Certificate[] pcerts =
(java.security.cert.Certificate[]) package2certs.get(pname);
if (pcerts == null) {
// first class in this package gets to define which
// certificates must be the same for all other classes
// in this package
if (cs != null) {
pcerts = cs.getCertificates();
}
if (pcerts == null) {
if (nocerts == null)
nocerts = new java.security.cert.Certificate[0];
pcerts = nocerts;
}
package2certs.put(pname, pcerts);
} else {
java.security.cert.Certificate[] certs = null;
if (cs != null) {
certs = cs.getCertificates();
}
if (!compareCerts(pcerts,certs)) {
throw new SecurityException("class \""+ name+
"\"'s signer information does not match signer information of other classes in the same package");
}
}
}
/**
* check to make sure the certs for the new class (certs) are
* the same as the certs for the first class inserted
* in the package (pcerts)
*/
private boolean compareCerts(java.security.cert.Certificate[] pcerts,
java.security.cert.Certificate[] certs)
{
// certs can be null, indicating no certs.
if ((certs == null) || (certs.length == 0)) {
return pcerts.length == 0;
}
// the length must be the same at this point
if (certs.length != pcerts.length)
return false;
// go through and make sure all the certs in one array
// are in the other and vice-versa.
boolean match;
for (int i=0; i < certs.length; i++) {
match = false;
for (int j=0; j < pcerts.length; j++) {
if (certs[i].equals(pcerts[j])) {
match = true;
break;
}
}
if (!match) return false;
}
// now do the same for pcerts
for (int i=0; i < pcerts.length; i++) {
match = false;
for (int j=0; j < certs.length; j++) {
if (pcerts[i].equals(certs[j])) {
match = true;
break;
}
}
if (!match) return false;
}
return true;
}
/**
* Links the specified class.
* This (misleadingly named) method may be used by a class loader to
* link a class. If the class <code>c</code> has already been linked,
* then this method simply returns. Otherwise, the class is linked
* as described in the "Execution" chapter of the <i>Java Language
* Specification</i>.
*
* @param c the class to link
* @exception NullPointerException if <code>c</code> is <code>null</code>.
* @see java.lang.ClassLoader#defineClass(java.lang.String,byte[],int,int)
*/
protected final void resolveClass(Class c) {
check();
resolveClass0(c);
}
/**
* Finds a class with the specified name, loading it if necessary.<p>
*
* Prior to the Java 2 SDK, this method loads a class from the local file
* system in a platform-dependent manner, and returns a class object
* that has no associated class loader.<p>
*
* Since the Java 2 SDK v1.2, this method loads the class through the
* system class loader(see {@link #getSystemClassLoader()}). Class objects
* returned might have <code>ClassLoader</code>s associated with them.
* Subclasses of <code>ClassLoader</code> need not usually call this
* method, because most class loaders need to override just {@link
* #findClass(String)}.<p>
*
* @param name the name of the class that is to be found
* @return the <code>Class</code> object for the specified
* <code>name</code>
* @exception ClassNotFoundException if the class could not be found
* @see #ClassLoader(ClassLoader)
* @see #getParent()
*/
protected final Class findSystemClass(String name)
throws ClassNotFoundException
{
check();
ClassLoader system = getSystemClassLoader();
if (system == null) {
return findBootstrapClass(name);
}
return system.loadClass(name);
}
/**
* Returns the parent class loader for delegation. Some implementations
* may use <code>null</code> to represent the bootstrap class
* loader. This method will return <code>null</code> in such
* implementations if this class loader's parent is the bootstrap
* class loader.
* <p>
* If a security manager is present, and the caller's class loader is
* not null and is not an ancestor of this class loader, then
* this method calls the security manager's <code>checkPermission</code>
* method with a <code>RuntimePermission("getClassLoader")</code>
* permission to ensure it's ok to access the parent class loader.
* If not, a <code>SecurityException</code> will be thrown.
*
* @return the parent <code>ClassLoader</code>
* @throws SecurityException
* if a security manager exists and its
* <code>checkPermission</code> method doesn't allow
* access to this class loader's parent class loader.
*
* @see SecurityManager#checkPermission
* @see java.lang.RuntimePermission
*
* @since 1.2
*/
public final ClassLoader getParent() {
if (parent == null)
return null;
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
ClassLoader ccl = getCallerClassLoader();
if (ccl != null && !isAncestor(ccl)) {
sm.checkPermission(getGetClassLoaderPerm());
}
}
return parent;
}
/**
* Sets the signers of a class. This should be called after defining a
* class.
*
* @param c the <code>Class</code> object
* @param signers the signers for the class
* @since JDK1.1
*/
protected final void setSigners(Class c, Object[] signers) {
check();
c.setSigners(signers);
}
private Class findBootstrapClass0(String name)
throws ClassNotFoundException {
check();
return findBootstrapClass(name);
}
private native Class defineClass0(String name, byte[] b, int off, int len,
ProtectionDomain pd);
private native void resolveClass0(Class c);
private native Class findBootstrapClass(String name)
throws ClassNotFoundException;
/*
* Check to make sure the class loader has been initialized.
*/
private void check() {
if (!initialized) {
throw new SecurityException("ClassLoader object not initialized");
}
}
/**
* Finds the class with the given name if it had been previously loaded
* through this class loader.
*
* @param name the class name
* @return the <code>Class</code> object, or <code>null</code> if
* the class has not been loaded
* @since JDK1.1
*/
protected native final Class findLoadedClass(String name);
/**
* Finds the resource with the given name. A resource is some data
* (images, audio, text, etc) that can be accessed by class code in a way
* that is independent of the location of the code.<p>
*
* The name of a resource is a "/"-separated path name that identifies
* the resource.<p>
*
* This method will first search the parent class loader for the resource;
* if the parent is <code>null</code> the path of the class loader
* built-in to the virtual machine is searched. That failing, this method
* will call <code>findResource</code> to find the resource.<p>
*
* @param name resource name
* @return a URL for reading the resource, or <code>null</code> if
* the resource could not be found or the caller doesn't have
* adequate privileges to get the resource.
* @since JDK1.1
* @see #findResource(String)
*/
public URL getResource(String name) {
URL url;
if (parent != null) {
url = parent.getResource(name);
} else {
url = getBootstrapResource(name);
}
if (url == null) {
url = findResource(name);
}
return url;
}
/**
* Finds all the resources with the given name. A resource is some data
* (images, audio, text, etc) that can be accessed by class code in a way
* that is independent of the location of the code.<p>
*
* The name of a resource is a "/"-separated path name that identifies the
* resource.<p>
*
* The search order is described in the documentation for {@link
* #getResource(String)}.<p>
*
* @param name resource name
* @return an enumeration of URL to the resource. If no resources could
* be found, the enumeration will be empty. Resources that the
* doesn't have access to will not be in the enumeration.
* @throws IOException if I/O errors occur
* @since 1.2
* @see #getResource
* @see #findResources
*/
public final Enumeration getResources(String name) throws IOException {
Enumeration[] tmp = new Enumeration[2];
if (parent != null) {
tmp[0] = parent.getResources(name);
} else {
tmp[0] = getBootstrapResources(name);
}
tmp[1] = findResources(name);
return new CompoundEnumeration(tmp);
}
/**
* Returns an Enumeration of URLs representing all the resources with
* the given name. Class loader implementations should override this
* method to specify where to load resources from.
*
* @param name the resource name
* @return an Enumeration of URLs for the resources
* @throws IOException if I/O errors occur
* @since 1.2
*/
protected Enumeration findResources(String name) throws IOException {
return new CompoundEnumeration(new Enumeration[0]);
}
/**
* Finds the resource with the given name. Class loader
* implementations should override this method to specify where to
* find resources.
*
* @param name the resource name
* @return a URL for reading the resource, or <code>null</code>
* if the resource could not be found
* @since 1.2
*/
protected URL findResource(String name) {
return null;
}
/**
* Find a resource of the specified name from the search path used to load
* classes.<p>
*
* In JDK1.1, the search path used is that of the virtual machine's
* built-in class loader.<p>
*
* Since the Java 2 SDK v1.2, this method locates the resource through the system class
* loader (see {@link #getSystemClassLoader()}).
*
* @param name the resource name
* @return a URL for reading the resource, or <code>null</code> if
* the resource could not be found
* @since JDK1.1
*/
public static URL getSystemResource(String name) {
ClassLoader system = getSystemClassLoader();
if (system == null) {
return getBootstrapResource(name);
}
return system.getResource(name);
}
/**
* Find resources from the VM's built-in classloader.
*/
private static URL getBootstrapResource(String name) {
URLClassPath ucp = getBootstrapClassPath();
Resource res = ucp.getResource(name);
return res != null ? res.getURL() : null;
}
/**
* Finds all resources of the specified name from the search path used to
* load classes. The resources thus found are returned as an
* <code>Enumeration</code> of <code>URL</code> objects. <p>
*
* The search order is described in the documentation for {@link
* #getSystemResource(String)}. <p>
*
* @param name the resource name
* @return an enumeration of resource URLs
* @throws IOException if I/O errors occur
* @since 1.2
*/
public static Enumeration getSystemResources(String name)
throws IOException
{
ClassLoader system = getSystemClassLoader();
if (system == null) {
return getBootstrapResources(name);
}
return system.getResources(name);
}
/**
* Find resources from the VM's built-in classloader.
*/
private static Enumeration getBootstrapResources(String name)
throws IOException
{
final Enumeration e = getBootstrapClassPath().getResources(name);
return new Enumeration () {
public Object nextElement() {
return ((Resource)e.nextElement()).getURL();
}
public boolean hasMoreElements() {
return e.hasMoreElements();
}
};
}
/*
* Returns the URLClassPath that is used for finding system resources.
*/
static URLClassPath getBootstrapClassPath() {
if (bootstrapClassPath == null) {
bootstrapClassPath = sun.misc.Launcher.getBootstrapClassPath();
}
return bootstrapClassPath;
}
private static URLClassPath bootstrapClassPath;
/**
* Returns an input stream for reading the specified resource.
*
* The search order is described in the documentation for {@link
* #getResource(String)}.<p>
*
* @param name the resource name
* @return an input stream for reading the resource, or <code>null</code>
* if the resource could not be found
* @since JDK1.1
*/
public InputStream getResourceAsStream(String name) {
URL url = getResource(name);
try {
return url != null ? url.openStream() : null;
} catch (IOException e) {
return null;
}
}
/**
* Open for reading, a resource of the specified name from the search path
* used to load classes.<p>
*
* The search order is described in the documentation for {@link
* #getSystemResource(String)}. <p>
*
* @param name the resource name
* @return an input stream for reading the resource, or <code>null</code>
* if the resource could not be found
* @since JDK1.1
*/
public static InputStream getSystemResourceAsStream(String name) {
URL url = getSystemResource(name);
try {
return url != null ? url.openStream() : null;
} catch (IOException e) {
return null;
}
}
/**
* Returns the system class loader for delegation. This is the default
* delegation parent for new <code>ClassLoader</code> instances, and
* is typically the class loader used to start the application.
* <p>
* This method is first invoked early in the runtime's startup
* sequence, at which point it creates the system class loader
* and sets it as the context class loader of the invoking
* <tt>Thread</tt>.
* <p>
* The default system class loader is an implementation-dependent
* instance of this class.
* <p>
* If the system property <tt>java.system.class.loader</tt> is
* defined when this method is first invoked then the value of that
* property is taken to be the name of a class that will be returned as
* the system class loader. The class is loaded using the default system
* class loader and must define a public constructor that takes a single
* parameter of type <tt>ClassLoader</tt> which is used
* as the delegation parent. An instance is then created using this
* constructor with the default system class loader as the parameter.
* The resulting class loader is defined to be the system class loader.
* <p>
* If a security manager is present, and the caller's class loader is
* not null and the caller's class loader is not the same as or an ancestor of
* the system class loader, then
* this method calls the security manager's <code>checkPermission</code>
* method with a <code>RuntimePermission("getClassLoader")</code>
* permission to ensure it's ok to access the system class loader.
* If not, a <code>SecurityException</code> will be thrown.
*
* @return the system <code>ClassLoader</code> for delegation, or
* <code>null</code> if none
* @throws SecurityException
* if a security manager exists and its
* <code>checkPermission</code> method doesn't allow
* access to the system class loader.
* @throws IllegalStateException
* if invoked recursively during the construction
* of the class loader specified by the
* <code>java.system.class.loader</code> property.
* @throws Error
* if the system property <tt>java.system.class.loader</tt>
* is defined but the named class could not be loaded, the
* provider class does not define the required constructor, or an
* exception is thrown by that constructor when it is invoked. The
* underlying cause of the error can be retrieved via the
* {@link Throwable#getCause()} method.
* @see SecurityManager#checkPermission
* @see java.lang.RuntimePermission
* @revised 1.4
*/
public static ClassLoader getSystemClassLoader() {
initSystemClassLoader();
if (scl == null) {
return null;
}
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
ClassLoader ccl = getCallerClassLoader();
if (ccl != null && ccl != scl && !scl.isAncestor(ccl)) {
sm.checkPermission(getGetClassLoaderPerm());
}
}
return scl;
}
private static synchronized void initSystemClassLoader() {
if (!sclSet) {
if (scl != null)
throw new IllegalStateException("recursive call");
sun.misc.Launcher l = sun.misc.Launcher.getLauncher();
if (l != null) {
Throwable oops = null;
scl = l.getClassLoader();
try {
PrivilegedExceptionAction a;
a = new SystemClassLoaderAction(scl);
scl = (ClassLoader) AccessController.doPrivileged(a);
} catch (PrivilegedActionException pae) {
oops = pae.getCause();
if (oops instanceof InvocationTargetException) {
oops = oops.getCause();
}
}
if (oops != null) {
if (oops instanceof Error) {
throw (Error) oops;
} else {
// wrap the exception
throw new Error(oops);
}
}
}
sclSet = true;
}
}
// Returns true if the specified class loader can be found
// in this class loader's delegation chain.
boolean isAncestor(ClassLoader cl) {
ClassLoader acl = this;
do {
acl = acl.parent;
if (cl == acl) {
return true;
}
} while (acl != null);
return false;
}
// Returns the caller's class loader, or null if none.
// NOTE this must always be called when there is exactly one
// intervening frame from the core libraries on the stack between
// this method's invocation and the desired caller.
static ClassLoader getCallerClassLoader() {
// NOTE use of more generic Reflection.getCallerClass()
Class caller = Reflection.getCallerClass(3);
// This can be null if the VM is requesting it
if (caller == null) {
return null;
}
// Circumvent security check since this is package-private
return caller.getClassLoader0();
}
// The class loader for the system
private static ClassLoader scl;
// Set to true once the system class loader has been set
private static boolean sclSet;
// Permission to access system or parent class loader
private static RuntimePermission getClassLoaderPerm = null;
static RuntimePermission getGetClassLoaderPerm()
{
if (getClassLoaderPerm == null)
getClassLoaderPerm = new RuntimePermission("getClassLoader");
return getClassLoaderPerm;
}
/**
* Defines a package by name in this ClassLoader. This allows class
* loaders to define the packages for their classes. Packages must be
* created before the class is defined, and package names must be
* unique within a class loader and cannot be redefined or changed
* once created.
*
* @param name the package name
* @param specTitle the specification title
* @param specVersion the specification version
* @param specVendor the specification vendor
* @param implTitle the implementation title
* @param implVersion the implementation version
* @param implVendor the implementation vendor
* @param sealBase If not null, then this package is sealed with
* respect to the given code source URL. Otherwise,
* the package is not sealed.
* @return the newly defined <code>Package</code> object
* @exception IllegalArgumentException if package name duplicates an
* existing package either in this class loader or one of
* its ancestors
* @since 1.2
*/
protected Package definePackage(String name, String specTitle,
String specVersion, String specVendor,
String implTitle, String implVersion,
String implVendor, URL sealBase)
throws IllegalArgumentException
{
synchronized (packages) {
Package pkg = getPackage(name);
if (pkg != null) {
throw new IllegalArgumentException(name);
}
pkg = new Package(name, specTitle, specVersion, specVendor,
implTitle, implVersion, implVendor,
sealBase);
packages.put(name, pkg);
return pkg;
}
}
/**
* Returns a Package that has been defined by this class loader or any
* of its ancestors.
*
* @param name the package name
* @return the Package corresponding to the given name, or null if not
* found
* @since 1.2
*/
protected Package getPackage(String name) {
synchronized (packages) {
Package pkg = (Package)packages.get(name);
if (pkg == null) {
if (parent != null) {
pkg = parent.getPackage(name);
} else {
pkg = Package.getSystemPackage(name);
}
if (pkg != null) {
packages.put(name, pkg);
}
}
return pkg;
}
}
/**
* Returns all of the Packages defined by this class loader and its
* ancestors.
*
* @return the array of <code>Package</code> objects defined by this
* <code>ClassLoader</code>
* @since 1.2
*/
protected Package[] getPackages() {
Map map;
synchronized (packages) {
map = (Map)packages.clone();
}
Package[] pkgs;
if (parent != null) {
pkgs = parent.getPackages();
} else {
pkgs = Package.getSystemPackages();
}
if (pkgs != null) {
for (int i = 0; i < pkgs.length; i++) {
String pkgName = pkgs[i].getName();
if (map.get(pkgName) == null) {
map.put(pkgName, pkgs[i]);
}
}
}
return (Package[])map.values().toArray(new Package[map.size()]);
}
/**
* Returns the absolute path name of a native library. The VM
* invokes this method to locate the native libraries that belong
* to classes loaded with this class loader. If this method returns
* <code>null</code>, the VM searches the library along the path
* specified as the <code>java.library.path</code> property.
*
* @param libname the library name
* @return the absolute path of the native library
* @see java.lang.System#loadLibrary(java.lang.String)
* @see java.lang.System#mapLibraryName(java.lang.String)
* @since 1.2
*/
protected String findLibrary(String libname) {
return null;
}
/**
* The inner class NativeLibrary denotes a loaded native library
* instance. Every classloader contains a vector of loaded native
* libraries in the private field <code>nativeLibraries</code>.
* The native libraries loaded into the system are entered into
* the <code>systemNativeLibraries</code> vector.
*
* Every native library reuqires a particular version of JNI. This
* is denoted by the private jniVersion field. This field is set
* by the VM when it loads the library, and used by the VM to pass
* the correct version of JNI to the native methods.
*
* @version 1.162, 03/19/02
* @see java.lang.ClassLoader
* @since 1.2
*/
static class NativeLibrary {
/* opaque handle to native library, used in native code. */
long handle;
/* the version of JNI environment the native library requires. */
private int jniVersion;
/* the class from which the library is loaded, also indicates
the loader this native library belongs. */
private Class fromClass;
/* the canonicalized name of the native library. */
String name;
native void load(String name);
native long find(String name);
native void unload();
public NativeLibrary(Class fromClass, String name) {
this.name = name;
this.fromClass = fromClass;
}
protected void finalize() {
synchronized (loadedLibraryNames) {
if (fromClass.getClassLoader() != null && handle != 0) {
/* remove the native library name */
int size = loadedLibraryNames.size();
for (int i = 0; i < size; i++) {
if (name.equals(loadedLibraryNames.elementAt(i))) {
loadedLibraryNames.removeElementAt(i);
break;
}
}
/* unload the library. */
ClassLoader.nativeLibraryContext.push(this);
try {
unload();
} finally {
ClassLoader.nativeLibraryContext.pop();
}
}
}
}
/* Called in the VM to determine the context class in
JNI_Load/JNI_Unload */
static Class getFromClass() {
return ((NativeLibrary)
(ClassLoader.nativeLibraryContext.peek())).fromClass;
}
}
/* the "default" domain. Set as the default ProtectionDomain
* on newly created classses.
*/
private ProtectionDomain defaultDomain = null;
/*
* returns (and initializes) the default domain.
*/
private synchronized ProtectionDomain getDefaultDomain() {
if (defaultDomain == null) {
CodeSource cs = new CodeSource(null, null);
defaultDomain = new ProtectionDomain(cs, null, this, null);
}
return defaultDomain;
}
/* All native library names we've loaded. */
private static Vector loadedLibraryNames = new Vector();
/* Native libraries belonging to system classes. */
private static Vector systemNativeLibraries = new Vector();
/* Native libraries associated with the class loader. */
private Vector nativeLibraries = new Vector();
/* native libraries being loaded/unloaded. */
private static Stack nativeLibraryContext = new Stack();
/* The paths searched for libraries */
static private String usr_paths[];
static private String sys_paths[];
private static String[] initializePath(String propname) {
String ldpath = System.getProperty(propname, "");
String ps = File.pathSeparator;
int ldlen = ldpath.length();
int i, j, n;
// Count the separators in the path
i = ldpath.indexOf(ps);
n = 0;
while (i >= 0) {
n++;
i = ldpath.indexOf(ps, i+1);
}
// allocate the array of paths - n :'s = n + 1 path elements
String[] paths = new String[n + 1];
// Fill the array with paths from the ldpath
n = i = 0;
j = ldpath.indexOf(ps);
while (j >= 0) {
if (j - i > 0) {
paths[n++] = ldpath.substring(i, j);
} else if (j - i == 0) {
paths[n++] = ".";
}
i = j + 1;
j = ldpath.indexOf(ps, i);
}
paths[n] = ldpath.substring(i, ldlen);
return paths;
}
/* Called in the java.lang.Runtime class to implement load
* and loadLibrary.
*/
static void loadLibrary(Class fromClass, String name,
boolean isAbsolute) {
ClassLoader loader =
(fromClass == null) ? null : fromClass.getClassLoader();
if (sys_paths == null) {
usr_paths = initializePath("java.library.path");
sys_paths = initializePath("sun.boot.library.path");
}
if (isAbsolute) {
if (loadLibrary0(fromClass, new File(name))) {
return;
}
throw new UnsatisfiedLinkError("Can't load library: " + name);
}
if (loader != null) {
String libfilename = loader.findLibrary(name);
if (libfilename != null) {
File libfile = new File(libfilename);
if (!libfile.isAbsolute()) {
throw new UnsatisfiedLinkError(
"ClassLoader.findLibrary failed to return an absolute path: " + libfilename);
}
if (loadLibrary0(fromClass, libfile)) {
return;
}
throw new UnsatisfiedLinkError ("Can't load " + libfilename);
}
}
for (int i = 0 ; i < sys_paths.length ; i++) {
File libfile = new File(sys_paths[i], System.mapLibraryName(name));
if (loadLibrary0(fromClass, libfile)) {
return;
}
}
if (loader != null) {
for (int i = 0 ; i < usr_paths.length ; i++) {
File libfile = new File(usr_paths[i],
System.mapLibraryName(name));
if (loadLibrary0(fromClass, libfile)) {
return;
}
}
}
// Oops, it failed
throw new UnsatisfiedLinkError("no " + name + " in java.library.path");
}
private static boolean loadLibrary0(Class fromClass, final File file) {
Boolean exists = (Boolean)
AccessController.doPrivileged(new PrivilegedAction() {
public Object run() {
return new Boolean(file.exists());
}
});
if (!exists.booleanValue()) {
return false;
}
String name;
try {
name = file.getCanonicalPath();
} catch (IOException e) {
return false;
}
ClassLoader loader =
(fromClass == null) ? null : fromClass.getClassLoader();
Vector libs =
loader != null ? loader.nativeLibraries : systemNativeLibraries;
synchronized (libs) {
int size = libs.size();
for (int i = 0; i < size; i++) {
NativeLibrary lib = (NativeLibrary)libs.elementAt(i);
if (name.equals(lib.name)) {
return true;
}
}
synchronized (loadedLibraryNames) {
if (loadedLibraryNames.contains(name)) {
throw new UnsatisfiedLinkError
("Native Library " +
name +
" already loaded in another classloader");
}
/* If the library is being loaded (must be by
* the same thread, because Runtime.load and
* Runtime.loadLibrary are synchronous). The
* reason is can occur is that the JNI_OnLoad
* function can cause another loadLibrary call.
*
* Thus we can use a static stack to hold the list
* of libraries we are loading.
*
* If there is a pending load operation for the
* library, we immediately return success; otherwise,
* we raise UnsatisfiedLinkError.
*/
int n = nativeLibraryContext.size();
for (int i = 0; i < n; i++) {
NativeLibrary lib = (NativeLibrary)
nativeLibraryContext.elementAt(i);
if (name.equals(lib.name)) {
if (loader == lib.fromClass.getClassLoader()) {
return true;
} else {
throw new UnsatisfiedLinkError
("Native Library " +
name +
" is being loaded in another classloader");
}
}
}
NativeLibrary lib = new NativeLibrary(fromClass, name);
nativeLibraryContext.push(lib);
try {
lib.load(name);
} finally {
nativeLibraryContext.pop();
}
if (lib.handle != 0) {
loadedLibraryNames.addElement(name);
libs.addElement(lib);
return true;
}
return false;
}
}
}
/* Called in the VM class linking code. */
static long findNative(ClassLoader loader, String name) {
Vector libs =
loader != null ? loader.nativeLibraries : systemNativeLibraries;
synchronized (libs) {
int size = libs.size();
for (int i = 0; i < size; i++) {
NativeLibrary lib = (NativeLibrary)libs.elementAt(i);
long entry = lib.find(name);
if (entry != 0)
return entry;
}
}
return 0;
}
/*
* The default toggle for assertion checking.
*/
private boolean defaultAssertionStatus = false;
/*
* Maps String packageName to Boolean package default assertion status
* Note that the default package is placed under a null map key.
* If this field is null then we are delegating assertion status queries
* to the VM, i.e., none of this ClassLoader's assertion status
* modification methods have been called.
*/
private Map packageAssertionStatus = null;
/*
* Maps String fullyQualifiedClassName to Boolean assertionStatus
* If this field is null then we are delegating assertion status queries
* to the VM, i.e., none of this ClassLoader's assertion status
* modification methods have been called.
*/
Map classAssertionStatus = null;
/**
* Sets the default assertion status for this class loader. This setting
* determines whether classes loaded by this class loader and initialized
* in the future will have assertions enabled or disabled by default.
* This setting may be overridden on a per-package or per-class basis by
* invoking {@link #setPackageAssertionStatus(String,boolean)} or {@link
* #setClassAssertionStatus(String,boolean)}.
*
* @param enabled <tt>true</tt> if classes loaded by this class loader
* will henceforth have assertions enabled by default,
* <tt>false</tt> if they will have assertions disabled by default.
* @since 1.4
*/
public synchronized void setDefaultAssertionStatus(boolean enabled) {
if (classAssertionStatus == null)
initializeJavaAssertionMaps();
defaultAssertionStatus = enabled;
}
/**
* Sets the package default assertion status for the named
* package. The package default assertion status determines the
* assertion status for classes initialized in the future that belong
* to the named package or any of its "subpackages."
* <p>
* A subpackage of a package named p is any package whose name
* begins with "p." . For example, <tt>javax.swing.text</tt> is
* a subpackage of <tt>javax.swing</tt>, and both <tt>java.util</tt>
* and <tt>java.lang.reflect</tt> are subpackages of <tt>java</tt>.
* <p>
* In the event that multiple package defaults apply to a given
* class, the package default pertaining to the most specific package
* takes precedence over the others. For example, if
* <tt>javax.lang</tt> and <tt>javax.lang.reflect</tt> both have
* package defaults associated with them, the latter package
* default applies to classes in <tt>javax.lang.reflect</tt>.
* <p>
* Package defaults take precedence over the class loader's default
* assertion status, and may be overridden on a per-class basis by
* invoking {@link #setClassAssertionStatus(String,boolean)}.
*
* @param packageName the name of the package whose package default
* assertion status is to be set. A null value
* indicates the unnamed package that is "current"
* (JLS 7.4.2).
* @param enabled <tt>true</tt> if classes loaded by this classloader
* and belonging to the named package or any of its subpackages
* will have assertions enabled by default, <tt>false</tt> if they
* will have assertions disabled by default.
* @since 1.4
*/
public synchronized void setPackageAssertionStatus(String packageName,
boolean enabled)
{
if (packageAssertionStatus == null)
initializeJavaAssertionMaps();
packageAssertionStatus.put(packageName, Boolean.valueOf(enabled));
}
/**
* Sets the desired assertion status for the named top-level class in
* this class loader and any nested classes contained therein.
* This setting takes precedence over the class loader's default
* assertion status, and over any applicable per-package default.
* This method has no effect if the named class has already been
* initialized. (Once a class is initialized, its assertion status cannot
* change.)
* <p>
* If the named class is not a top-level class, this call will have no
* effect on the actual assertion status of any class, and its return
* value is undefined.
*
* @param className the fully qualified class name of the top-level class
* whose assertion status is to be set.
* @param enabled <tt>true</tt> if the named class is to have assertions
* enabled when (and if) it is initialized, <tt>false</tt> if the
* class is to have assertions disabled.
* @since 1.4
*/
public synchronized void setClassAssertionStatus(String className,
boolean enabled)
{
if (classAssertionStatus == null)
initializeJavaAssertionMaps();
classAssertionStatus.put(className, Boolean.valueOf(enabled));
}
/**
* Sets the default assertion status for this class loader to
* <tt>false</tt> and discards any package defaults or class assertion
* status settings associated with the class loader. This call is
* provided so that class loaders can be made to ignore any command line
* or persistent assertion status settings and "start with a clean slate."
*
* @since 1.4
*/
public synchronized void clearAssertionStatus() {
/*
* Whether or not "Java assertion maps" are initialized, set
* them to empty maps, effectively ignoring any present settings.
*/
classAssertionStatus = new HashMap();
packageAssertionStatus = new HashMap();
defaultAssertionStatus = false;
}
/**
* Returns the assertion status that would be assigned to the specified
* class if it were to be initialized at the time this method is invoked.
* If the named class has had its assertion status set, the most recent
* setting will be returned; otherwise, if any package default assertion
* status pertains to this class, the most recent setting for the most
* specific pertinent package default assertion status is returned;
* otherwise, this class loader's default assertion status is returned.
*
* @param className the fully qualified class name of the class whose
* desired assertion status is being queried.
* @return the desired assertion status of the specified class.
* @see #setClassAssertionStatus(String,boolean)
* @see #setPackageAssertionStatus(String,boolean)
* @see #setDefaultAssertionStatus(boolean)
* @since 1.4
*/
synchronized boolean desiredAssertionStatus(String className) {
Boolean result;
// assert classAssertionStatus != null;
// assert packageAssertionStatus != null;
// Check for a class entry
result = (Boolean)classAssertionStatus.get(className);
if (result != null)
return result.booleanValue();
// Check for most specific package entry
int dotIndex = className.lastIndexOf(".");
if (dotIndex < 0) { // default package
result = (Boolean)packageAssertionStatus.get(null);
if (result != null)
return result.booleanValue();
}
while(dotIndex > 0) {
className = className.substring(0, dotIndex);
result = (Boolean)packageAssertionStatus.get(className);
if (result != null)
return result.booleanValue();
dotIndex = className.lastIndexOf(".", dotIndex-1);
}
// Return the classloader default
return defaultAssertionStatus;
}
// Set up the assertions with information provided by the VM.
private void initializeJavaAssertionMaps() {
// assert Thread.holdsLock(this);
classAssertionStatus = new HashMap();
packageAssertionStatus = new HashMap();
AssertionStatusDirectives directives = retrieveDirectives();
for(int i=0; i<directives.classes.length; i++)
classAssertionStatus.put(directives.classes[i],
Boolean.valueOf(directives.classEnabled[i]));
for(int i=0; i<directives.packages.length; i++)
packageAssertionStatus.put(directives.packages[i],
Boolean.valueOf(directives.packageEnabled[i]));
defaultAssertionStatus = directives.deflt;
}
// Retrieves the assertion directives from the VM.
private static native AssertionStatusDirectives retrieveDirectives();
}
class SystemClassLoaderAction implements PrivilegedExceptionAction {
private ClassLoader parent;
SystemClassLoaderAction(ClassLoader parent) {
this.parent = parent;
}
public Object run() throws Exception {
ClassLoader sys;
Constructor ctor;
Class c;
Class cp[] = { ClassLoader.class };
Object params[] = { parent };
String cls = System.getProperty("java.system.class.loader");
if (cls == null) {
return parent;
}
c = Class.forName(cls, true, parent);
ctor = c.getDeclaredConstructor(cp);
sys = (ClassLoader) ctor.newInstance(params);
Thread.currentThread().setContextClassLoader(sys);
return sys;
}
}