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The Launcher.java Java example source code
/*
* Copyright (c) 1998, 2011, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package sun.misc;
import java.io.File;
import java.io.IOException;
import java.io.FilePermission;
import java.net.URL;
import java.net.URLClassLoader;
import java.net.MalformedURLException;
import java.net.URLStreamHandler;
import java.net.URLStreamHandlerFactory;
import java.util.HashSet;
import java.util.StringTokenizer;
import java.util.Set;
import java.util.Vector;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedExceptionAction;
import java.security.AccessControlContext;
import java.security.PermissionCollection;
import java.security.Permissions;
import java.security.Permission;
import java.security.ProtectionDomain;
import java.security.CodeSource;
import sun.security.util.SecurityConstants;
import sun.net.www.ParseUtil;
/**
* This class is used by the system to launch the main application.
Launcher */
public class Launcher {
private static URLStreamHandlerFactory factory = new Factory();
private static Launcher launcher = new Launcher();
private static String bootClassPath =
System.getProperty("sun.boot.class.path");
public static Launcher getLauncher() {
return launcher;
}
private ClassLoader loader;
public Launcher() {
// Create the extension class loader
ClassLoader extcl;
try {
extcl = ExtClassLoader.getExtClassLoader();
} catch (IOException e) {
throw new InternalError(
"Could not create extension class loader", e);
}
// Now create the class loader to use to launch the application
try {
loader = AppClassLoader.getAppClassLoader(extcl);
} catch (IOException e) {
throw new InternalError(
"Could not create application class loader", e);
}
// Also set the context class loader for the primordial thread.
Thread.currentThread().setContextClassLoader(loader);
// Finally, install a security manager if requested
String s = System.getProperty("java.security.manager");
if (s != null) {
SecurityManager sm = null;
if ("".equals(s) || "default".equals(s)) {
sm = new java.lang.SecurityManager();
} else {
try {
sm = (SecurityManager)loader.loadClass(s).newInstance();
} catch (IllegalAccessException e) {
} catch (InstantiationException e) {
} catch (ClassNotFoundException e) {
} catch (ClassCastException e) {
}
}
if (sm != null) {
System.setSecurityManager(sm);
} else {
throw new InternalError(
"Could not create SecurityManager: " + s);
}
}
}
/*
* Returns the class loader used to launch the main application.
*/
public ClassLoader getClassLoader() {
return loader;
}
/*
* The class loader used for loading installed extensions.
*/
static class ExtClassLoader extends URLClassLoader {
static {
ClassLoader.registerAsParallelCapable();
}
/**
* create an ExtClassLoader. The ExtClassLoader is created
* within a context that limits which files it can read
*/
public static ExtClassLoader getExtClassLoader() throws IOException
{
final File[] dirs = getExtDirs();
try {
// Prior implementations of this doPrivileged() block supplied
// aa synthesized ACC via a call to the private method
// ExtClassLoader.getContext().
return AccessController.doPrivileged(
new PrivilegedExceptionAction<ExtClassLoader>() {
public ExtClassLoader run() throws IOException {
int len = dirs.length;
for (int i = 0; i < len; i++) {
MetaIndex.registerDirectory(dirs[i]);
}
return new ExtClassLoader(dirs);
}
});
} catch (java.security.PrivilegedActionException e) {
throw (IOException) e.getException();
}
}
void addExtURL(URL url) {
super.addURL(url);
}
/*
* Creates a new ExtClassLoader for the specified directories.
*/
public ExtClassLoader(File[] dirs) throws IOException {
super(getExtURLs(dirs), null, factory);
}
private static File[] getExtDirs() {
String s = System.getProperty("java.ext.dirs");
File[] dirs;
if (s != null) {
StringTokenizer st =
new StringTokenizer(s, File.pathSeparator);
int count = st.countTokens();
dirs = new File[count];
for (int i = 0; i < count; i++) {
dirs[i] = new File(st.nextToken());
}
} else {
dirs = new File[0];
}
return dirs;
}
private static URL[] getExtURLs(File[] dirs) throws IOException {
Vector<URL> urls = new Vector();
for (int i = 0; i < dirs.length; i++) {
String[] files = dirs[i].list();
if (files != null) {
for (int j = 0; j < files.length; j++) {
if (!files[j].equals("meta-index")) {
File f = new File(dirs[i], files[j]);
urls.add(getFileURL(f));
}
}
}
}
URL[] ua = new URL[urls.size()];
urls.copyInto(ua);
return ua;
}
/*
* Searches the installed extension directories for the specified
* library name. For each extension directory, we first look for
* the native library in the subdirectory whose name is the value
* of the system property <code>os.arch. Failing that, we
* look in the extension directory itself.
*/
public String findLibrary(String name) {
name = System.mapLibraryName(name);
URL[] urls = super.getURLs();
File prevDir = null;
for (int i = 0; i < urls.length; i++) {
// Get the ext directory from the URL
File dir = new File(urls[i].getPath()).getParentFile();
if (dir != null && !dir.equals(prevDir)) {
// Look in architecture-specific subdirectory first
// Read from the saved system properties to avoid deadlock
String arch = VM.getSavedProperty("os.arch");
if (arch != null) {
File file = new File(new File(dir, arch), name);
if (file.exists()) {
return file.getAbsolutePath();
}
}
// Then check the extension directory
File file = new File(dir, name);
if (file.exists()) {
return file.getAbsolutePath();
}
}
prevDir = dir;
}
return null;
}
private static AccessControlContext getContext(File[] dirs)
throws IOException
{
PathPermissions perms =
new PathPermissions(dirs);
ProtectionDomain domain = new ProtectionDomain(
new CodeSource(perms.getCodeBase(),
(java.security.cert.Certificate[]) null),
perms);
AccessControlContext acc =
new AccessControlContext(new ProtectionDomain[] { domain });
return acc;
}
}
/**
* The class loader used for loading from java.class.path.
* runs in a restricted security context.
*/
static class AppClassLoader extends URLClassLoader {
static {
ClassLoader.registerAsParallelCapable();
}
public static ClassLoader getAppClassLoader(final ClassLoader extcl)
throws IOException
{
final String s = System.getProperty("java.class.path");
final File[] path = (s == null) ? new File[0] : getClassPath(s);
// Note: on bugid 4256530
// Prior implementations of this doPrivileged() block supplied
// a rather restrictive ACC via a call to the private method
// AppClassLoader.getContext(). This proved overly restrictive
// when loading classes. Specifically it prevent
// accessClassInPackage.sun.* grants from being honored.
//
return AccessController.doPrivileged(
new PrivilegedAction<AppClassLoader>() {
public AppClassLoader run() {
URL[] urls =
(s == null) ? new URL[0] : pathToURLs(path);
return new AppClassLoader(urls, extcl);
}
});
}
/*
* Creates a new AppClassLoader
*/
AppClassLoader(URL[] urls, ClassLoader parent) {
super(urls, parent, factory);
}
/**
* Override loadClass so we can checkPackageAccess.
*/
public Class<?> loadClass(String name, boolean resolve)
throws ClassNotFoundException
{
int i = name.lastIndexOf('.');
if (i != -1) {
SecurityManager sm = System.getSecurityManager();
if (sm != null) {
sm.checkPackageAccess(name.substring(0, i));
}
}
return (super.loadClass(name, resolve));
}
/**
* allow any classes loaded from classpath to exit the VM.
*/
protected PermissionCollection getPermissions(CodeSource codesource)
{
PermissionCollection perms = super.getPermissions(codesource);
perms.add(new RuntimePermission("exitVM"));
return perms;
}
/**
* This class loader supports dynamic additions to the class path
* at runtime.
*
* @see java.lang.instrument.Instrumentation#appendToSystemClassPathSearch
*/
private void appendToClassPathForInstrumentation(String path) {
assert(Thread.holdsLock(this));
// addURL is a no-op if path already contains the URL
super.addURL( getFileURL(new File(path)) );
}
/**
* create a context that can read any directories (recursively)
* mentioned in the class path. In the case of a jar, it has to
* be the directory containing the jar, not just the jar, as jar
* files might refer to other jar files.
*/
private static AccessControlContext getContext(File[] cp)
throws java.net.MalformedURLException
{
PathPermissions perms =
new PathPermissions(cp);
ProtectionDomain domain =
new ProtectionDomain(new CodeSource(perms.getCodeBase(),
(java.security.cert.Certificate[]) null),
perms);
AccessControlContext acc =
new AccessControlContext(new ProtectionDomain[] { domain });
return acc;
}
}
private static class BootClassPathHolder {
static final URLClassPath bcp;
static {
URL[] urls;
if (bootClassPath != null) {
urls = AccessController.doPrivileged(
new PrivilegedAction<URL[]>() {
public URL[] run() {
File[] classPath = getClassPath(bootClassPath);
int len = classPath.length;
Set<File> seenDirs = new HashSet();
for (int i = 0; i < len; i++) {
File curEntry = classPath[i];
// Negative test used to properly handle
// nonexistent jars on boot class path
if (!curEntry.isDirectory()) {
curEntry = curEntry.getParentFile();
}
if (curEntry != null && seenDirs.add(curEntry)) {
MetaIndex.registerDirectory(curEntry);
}
}
return pathToURLs(classPath);
}
}
);
} else {
urls = new URL[0];
}
bcp = new URLClassPath(urls, factory);
}
}
public static URLClassPath getBootstrapClassPath() {
return BootClassPathHolder.bcp;
}
private static URL[] pathToURLs(File[] path) {
URL[] urls = new URL[path.length];
for (int i = 0; i < path.length; i++) {
urls[i] = getFileURL(path[i]);
}
// DEBUG
//for (int i = 0; i < urls.length; i++) {
// System.out.println("urls[" + i + "] = " + '"' + urls[i] + '"');
//}
return urls;
}
private static File[] getClassPath(String cp) {
File[] path;
if (cp != null) {
int count = 0, maxCount = 1;
int pos = 0, lastPos = 0;
// Count the number of separators first
while ((pos = cp.indexOf(File.pathSeparator, lastPos)) != -1) {
maxCount++;
lastPos = pos + 1;
}
path = new File[maxCount];
lastPos = pos = 0;
// Now scan for each path component
while ((pos = cp.indexOf(File.pathSeparator, lastPos)) != -1) {
if (pos - lastPos > 0) {
path[count++] = new File(cp.substring(lastPos, pos));
} else {
// empty path component translates to "."
path[count++] = new File(".");
}
lastPos = pos + 1;
}
// Make sure we include the last path component
if (lastPos < cp.length()) {
path[count++] = new File(cp.substring(lastPos));
} else {
path[count++] = new File(".");
}
// Trim array to correct size
if (count != maxCount) {
File[] tmp = new File[count];
System.arraycopy(path, 0, tmp, 0, count);
path = tmp;
}
} else {
path = new File[0];
}
// DEBUG
//for (int i = 0; i < path.length; i++) {
// System.out.println("path[" + i + "] = " + '"' + path[i] + '"');
//}
return path;
}
private static URLStreamHandler fileHandler;
static URL getFileURL(File file) {
try {
file = file.getCanonicalFile();
} catch (IOException e) {}
try {
return ParseUtil.fileToEncodedURL(file);
} catch (MalformedURLException e) {
// Should never happen since we specify the protocol...
throw new InternalError(e);
}
}
/*
* The stream handler factory for loading system protocol handlers.
*/
private static class Factory implements URLStreamHandlerFactory {
private static String PREFIX = "sun.net.www.protocol";
public URLStreamHandler createURLStreamHandler(String protocol) {
String name = PREFIX + "." + protocol + ".Handler";
try {
Class<?> c = Class.forName(name);
return (URLStreamHandler)c.newInstance();
} catch (ReflectiveOperationException e) {
throw new InternalError("could not load " + protocol +
"system protocol handler", e);
}
}
}
}
class PathPermissions extends PermissionCollection {
// use serialVersionUID from JDK 1.2.2 for interoperability
private static final long serialVersionUID = 8133287259134945693L;
private File path[];
private Permissions perms;
URL codeBase;
PathPermissions(File path[])
{
this.path = path;
this.perms = null;
this.codeBase = null;
}
URL getCodeBase()
{
return codeBase;
}
public void add(java.security.Permission permission) {
throw new SecurityException("attempt to add a permission");
}
private synchronized void init()
{
if (perms != null)
return;
perms = new Permissions();
// this is needed to be able to create the classloader itself!
perms.add(SecurityConstants.CREATE_CLASSLOADER_PERMISSION);
// add permission to read any "java.*" property
perms.add(new java.util.PropertyPermission("java.*",
SecurityConstants.PROPERTY_READ_ACTION));
AccessController.doPrivileged(new PrivilegedAction<Void>() {
public Void run() {
for (int i=0; i < path.length; i++) {
File f = path[i];
String path;
try {
path = f.getCanonicalPath();
} catch (IOException ioe) {
path = f.getAbsolutePath();
}
if (i == 0) {
codeBase = Launcher.getFileURL(new File(path));
}
if (f.isDirectory()) {
if (path.endsWith(File.separator)) {
perms.add(new FilePermission(path+"-",
SecurityConstants.FILE_READ_ACTION));
} else {
perms.add(new FilePermission(
path + File.separator+"-",
SecurityConstants.FILE_READ_ACTION));
}
} else {
int endIndex = path.lastIndexOf(File.separatorChar);
if (endIndex != -1) {
path = path.substring(0, endIndex+1) + "-";
perms.add(new FilePermission(path,
SecurityConstants.FILE_READ_ACTION));
} else {
// XXX?
}
}
}
return null;
}
});
}
public boolean implies(java.security.Permission permission) {
if (perms == null)
init();
return perms.implies(permission);
}
public java.util.Enumeration<Permission> elements() {
if (perms == null)
init();
synchronized (perms) {
return perms.elements();
}
}
public String toString() {
if (perms == null)
init();
return perms.toString();
}
}
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