概述
Java中ClassLoader类源码
public abstract class ClassLoader {
private static native void registerNatives();
static {
registerNatives();
}
// 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();
// Invoked 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 final HashMap<String, Package> packages =
new HashMap<String, Package>();
private static Void checkCreateClassLoader() {
SecurityManager security = System.getSecurityManager();
if (security != null) {
security.checkCreateClassLoader();
}
return null;
}
private ClassLoader(Void unused, ClassLoader parent) {
this.parent = parent;
}
protected ClassLoader(ClassLoader parent) {
this(checkCreateClassLoader(), parent);
}
protected ClassLoader() {
this(checkCreateClassLoader(), getSystemClassLoader());
}
public Class<?> loadClass(String name) throws ClassNotFoundException {
return loadClass(name, false);
}
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 = findBootstrapClassOrNull(name);
}
} catch (ClassNotFoundException e) {
// ClassNotFoundException thrown if class not found
// from the non-null parent class loader
}
if (c == null) {
// If still not found, then invoke findClass in order
// to find the class.
c = findClass(name);
}
}
if (resolve) {
resolveClass(c);
}
return c;
}
// This method is invoked 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);
}
protected Class<?> findClass(String name) throws ClassNotFoundException {
throw new ClassNotFoundException(name);
}
@Deprecated
protected final Class<?> defineClass(byte[] b, int off, int len)
throws ClassFormatError
{
return defineClass(null, b, off, len, null);
}
protected final Class<?> defineClass(String name, byte[] b, int off, int len)
throws ClassFormatError
{
return defineClass(name, b, off, len, null);
}
private ProtectionDomain preDefineClass(String name,
ProtectionDomain protectionDomain)
{
if (!checkName(name))
throw new NoClassDefFoundError("IllegalName: " + name);
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());
return protectionDomain;
}
private String defineClassSourceLocation(ProtectionDomain protectionDomain)
{
CodeSource cs = protectionDomain.getCodeSource();
String source = null;
if (cs != null && cs.getLocation() != null) {
source = cs.getLocation().toString();
}
return source;
}
private Class defineTransformedClass(String name, byte[] b, int off, int len,
ProtectionDomain protectionDomain,
ClassFormatError cfe, String source,
boolean verify)
throws ClassFormatError
{
// Class format error - try to transform the bytecode and
// define the class again
//
Object[] transformers = ClassFileTransformer.getTransformers();
Class c = null;
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 = defineClass1(name, tb, 0, tb.length, protectionDomain, source,
verify);
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;
return c;
}
private void postDefineClass(Class c, ProtectionDomain protectionDomain)
{
if (protectionDomain.getCodeSource() != null) {
java.security.cert.Certificate certs[] =
protectionDomain.getCodeSource().getCertificates();
if (certs != null)
setSigners(c, certs);
}
}
protected final Class<?> defineClass(String name, byte[] b, int off, int len,
ProtectionDomain protectionDomain)
throws ClassFormatError
{
return defineClassCond(name, b, off, len, protectionDomain, true);
}
// Private method w/ an extra argument for skipping class verification
private final Class<?> defineClassCond(String name,
byte[] b, int off, int len,
ProtectionDomain protectionDomain,
boolean verify)
throws ClassFormatError
{
protectionDomain = preDefineClass(name, protectionDomain);
Class c = null;
String source = defineClassSourceLocation(protectionDomain);
try {
c = defineClass1(name, b, off, len, protectionDomain, source,
verify);
} catch (ClassFormatError cfe) {
c = defineTransformedClass(name, b, off, len, protectionDomain, cfe,
source, verify);
}
postDefineClass(c, protectionDomain);
return c;
}
protected final Class<?> defineClass(String name, java.nio.ByteBuffer b,
ProtectionDomain protectionDomain)
throws ClassFormatError
{
return defineClassCond(name, b, protectionDomain, true);
}
// Private method w/ an extra argument for skipping class verification
private final Class<?> defineClassCond(String name,
java.nio.ByteBuffer b,
ProtectionDomain protectionDomain,
boolean verify)
throws ClassFormatError
{
int len = b.remaining();
// Use byte[] if not a direct ByteBufer:
if (!b.isDirect()) {
if (b.hasArray()) {
return defineClassCond(name, b.array(),
b.position() + b.arrayOffset(), len,
protectionDomain, verify);
} else {
// no array, or read-only array
byte[] tb = new byte[len];
b.get(tb); // get bytes out of byte buffer.
return defineClassCond(name, tb, 0, len, protectionDomain,
verify);
}
}
protectionDomain = preDefineClass(name, protectionDomain);
Class c = null;
String source = defineClassSourceLocation(protectionDomain);
try {
c = defineClass2(name, b, b.position(), len, protectionDomain,
source, verify);
} catch (ClassFormatError cfe) {
byte[] tb = new byte[len];
b.get(tb); // get bytes out of byte buffer.
c = defineTransformedClass(name, tb, 0, len, protectionDomain, cfe,
source, verify);
}
postDefineClass(c, protectionDomain);
return c;
}
// Need to keep this one release after fixing 4735126 - see 4931983
private Class defineClass0(String name, byte[] b, int off, int len,
ProtectionDomain pd) {
return defineClass0(name, b, off, len, pd, true);
}
private native Class defineClass0(String name, byte[] b, int off, int len,
ProtectionDomain pd, boolean verify);
private native Class defineClass1(String name, byte[] b, int off, int len,
ProtectionDomain pd, String source,
boolean verify);
private native Class defineClass2(String name, java.nio.ByteBuffer b,
int off, int len, ProtectionDomain pd,
String source, boolean verify);
// true if the name is null or has the potential to be a valid binary name
private boolean checkName(String name) {
if ((name == null) || (name.length() == 0))
return true;
if ((name.indexOf('/') != -1)
|| (!VM.allowArraySyntax() && (name.charAt(0) == '[')))
return false;
return true;
}
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");
}
}
}
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;
}
protected final void resolveClass(Class<?> c) {
resolveClass0(c);
}
private native void resolveClass0(Class c);
protected final Class<?> findSystemClass(String name)
throws ClassNotFoundException
{
ClassLoader system = getSystemClassLoader();
if (system == null) {
if (!checkName(name))
throw new ClassNotFoundException(name);
Class cls = findBootstrapClass(name);
if (cls == null) {
throw new ClassNotFoundException(name);
}
return cls;
}
return system.loadClass(name);
}
private Class findBootstrapClassOrNull(String name)
{
if (!checkName(name)) return null;
return findBootstrapClass(name);
}
// return null if not found
private native Class findBootstrapClass(String name);
protected final Class<?> findLoadedClass(String name) {
if (!checkName(name))
return null;
return findLoadedClass0(name);
}
private native final Class findLoadedClass0(String name);
protected final void setSigners(Class<?> c, Object[] signers) {
c.setSigners(signers);
}
// -- Resource --
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;
}
public Enumeration<URL> 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);
}
protected URL findResource(String name) {
return null;
}
protected Enumeration<URL> findResources(String name) throws IOException {
return new CompoundEnumeration(new Enumeration[0]);
}
public static URL getSystemResource(String name) {
ClassLoader system = getSystemClassLoader();
if (system == null) {
return getBootstrapResource(name);
}
return system.getResource(name);
}
public static Enumeration<URL> getSystemResources(String name)
throws IOException
{
ClassLoader system = getSystemClassLoader();
if (system == null) {
return getBootstrapResources(name);
}
return system.getResources(name);
}
private static URL getBootstrapResource(String name) {
try {
// If this is a known JRE resource, ensure that its bundle is
// downloaded. If it isn't known, we just ignore the download
// failure and check to see if we can find the resource anyway
// (which is possible if the boot class path has been modified).
sun.jkernel.DownloadManager.getBootClassPathEntryForResource(name);
} catch (NoClassDefFoundError e) {
// This happens while Java itself is being compiled; DownloadManager
// isn't accessible when this code is first invoked. It isn't an
// issue, as if we can't find DownloadManager, we can safely assume
// that additional code is not available for download.
}
URLClassPath ucp = getBootstrapClassPath();
Resource res = ucp.getResource(name);
return res != null ? res.getURL() : null;
}
/**
* 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() {
return sun.misc.Launcher.getBootstrapClassPath();
}
public InputStream getResourceAsStream(String name) {
URL url = getResource(name);
try {
return url != null ? url.openStream() : null;
} catch (IOException e) {
return null;
}
}
public static InputStream getSystemResourceAsStream(String name) {
URL url = getSystemResource(name);
try {
return url != null ? url.openStream() : null;
} catch (IOException e) {
return null;
}
}
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(SecurityConstants.GET_CLASSLOADER_PERMISSION);
}
}
return parent;
}
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(SecurityConstants.GET_CLASSLOADER_PERMISSION);
}
}
return scl;
}
private static synchronized void initSystemClassLoader() {
if (!sclSet) {
if (scl != null)
throw new IllegalStateException("recursive invocation");
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 invoker's class loader, or null if none.
// NOTE: This must always be invoked when there is exactly one intervening
// frame from the core libraries on the stack between this method's
// invocation and the desired invoker.
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;
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, this);
packages.put(name, pkg);
return pkg;
}
}
protected Package getPackage(String name) {
Package pkg;
synchronized(packages) {
pkg = packages.get(name);
}
if (pkg == null) {
if (parent != null) {
pkg = parent.getPackage(name);
} else {
pkg = Package.getSystemPackage(name);
}
if (pkg != null) {
synchronized(packages) {
if (packages.get(name) != null) {
packages.put(name, pkg);
}
}
}
}
return pkg;
}
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()]);
}
protected String findLibrary(String libname) {
return null;
}
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();
}
}
}
}
// Invoked 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 classes.
private ProtectionDomain defaultDomain = null;
// Returns (and initializes) the default domain.
private synchronized ProtectionDomain getDefaultDomain() {
if (defaultDomain == null) {
CodeSource cs =
new CodeSource(null, (java.security.cert.Certificate[]) 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;
}
// Invoked in the java.lang.Runtime class to implement load and loadLibrary.
static void loadLibrary(Class fromClass, String name,
boolean isAbsolute) {
try {
if (!DownloadManager.isJREComplete() &&
!DownloadManager.isCurrentThreadDownloading()) {
DownloadManager.downloadFile("bin/" +
System.mapLibraryName(name));
// it doesn't matter if the downloadFile call returns false --
// it probably just means that this is a user library, as
// opposed to a JRE library
}
} catch (IOException e) {
throw new UnsatisfiedLinkError("Error downloading library " +
name + ": " + e);
} catch (NoClassDefFoundError e) {
// This happens while Java itself is being compiled; DownloadManager
// isn't accessible when this code is first invoked. It isn't an
// issue, as if we can't find DownloadManager, we can safely assume
// that additional code is not available for download.
}
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");
}
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;
}
}
}
// Invoked 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;
}
// -- Assertion management --
// 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 invoked.
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 invoked.
Map classAssertionStatus = null;
public synchronized void setDefaultAssertionStatus(boolean enabled) {
if (classAssertionStatus == null)
initializeJavaAssertionMaps();
defaultAssertionStatus = enabled;
}
public synchronized void setPackageAssertionStatus(String packageName,
boolean enabled)
{
if (packageAssertionStatus == null)
initializeJavaAssertionMaps();
packageAssertionStatus.put(packageName, Boolean.valueOf(enabled));
}
public synchronized void setClassAssertionStatus(String className,
boolean enabled)
{
if (classAssertionStatus == null)
initializeJavaAssertionMaps();
classAssertionStatus.put(className, Boolean.valueOf(enabled));
}
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;
}
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;
}
}
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