com.sun.istack.tools.ParallelWorldClassLoader Maven / Gradle / Ivy
/*
* Copyright (c) 1997, 2023 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Distribution License v. 1.0, which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
package com.sun.istack.tools;
import java.io.InputStream;
import java.io.ByteArrayOutputStream;
import java.io.Closeable;
import java.io.File;
import java.io.IOException;
import java.net.JarURLConnection;
import java.net.URISyntaxException;
import java.net.URL;
import java.net.MalformedURLException;
import java.net.URLConnection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Set;
import java.util.jar.JarFile;
import java.util.logging.Level;
import java.util.logging.Logger;
/**
* Load classes/resources from a side folder, so that
* classes of the same package can live in a single jar file.
*
*
* For example, with the following jar file:
*
* /
* +- foo
* +- X.class
* +- bar
* +- X.class
*
*
* {@link ParallelWorldClassLoader}("foo/") would load {@code X.class} from
* {@code /foo/X.class} (note that X is defined in the root package, not
* {@code foo.X}.
*
*
* This can be combined with {@link MaskingClassLoader} to mask classes which are loaded by the parent
* class loader so that the child class loader
* classes living in different folders are loaded
* before the parent class loader loads classes living the jar file publicly
* visible
* For example, with the following jar file:
*
* /
* +- foo
* +- X.class
* +- bar
* +-foo
* +- X.class
*
*
* {@link ParallelWorldClassLoader}(MaskingClassLoader.class.getClassLoader())
* would load {@code foo.X.class} from
* {@code /bar/foo.X.class} not the {@code foo.X.class}
* in the publicly visible place in the jar file, thus
* masking the parent classLoader from loading the class from {@code foo.X.class}
* (note that X is defined in the package foo, not
* {@code bar.foo.X}.
*
* @author Kohsuke Kawaguchi
*/
public class ParallelWorldClassLoader extends ClassLoader implements Closeable {
/**
* Strings like "prefix/", "abc/", or "" to indicate
* classes should be loaded normally.
*/
private final String prefix;
private final Set jars;
public ParallelWorldClassLoader(ClassLoader parent,String prefix) {
super(parent);
this.prefix = prefix;
jars = Collections.synchronizedSet(new HashSet<>());
}
@Override
protected Class findClass(String name) throws ClassNotFoundException {
StringBuilder sb = new StringBuilder(name.length()+prefix.length()+6);
sb.append(prefix).append(name.replace('.','/')).append(".class");
URL u = getParent().getResource(sb.toString());
if (u == null) {
throw new ClassNotFoundException(name);
}
InputStream is = null;
URLConnection con = null;
try {
con = u.openConnection();
is = con.getInputStream();
} catch (IOException ioe) {
throw new ClassNotFoundException(name);
}
if (is==null)
throw new ClassNotFoundException(name);
try {
ByteArrayOutputStream baos = new ByteArrayOutputStream();
byte[] buf = new byte[1024];
int len;
while((len=is.read(buf))>=0)
baos.write(buf,0,len);
buf = baos.toByteArray();
int packIndex = name.lastIndexOf('.');
if (packIndex != -1) {
String pkgname = name.substring(0, packIndex);
// Check if package already loaded.
Package pkg = getDefinedPackage(pkgname);
if (pkg == null) {
definePackage(pkgname, null, null, null, null, null, null, null);
}
}
return defineClass(name,buf,0,buf.length);
} catch (IOException e) {
throw new ClassNotFoundException(name,e);
} finally {
try {
if (con instanceof JarURLConnection) {
jars.add(((JarURLConnection) con).getJarFile());
}
} catch (IOException ioe) {
//ignore
}
try {
is.close();
} catch (IOException ioe) {
//ignore
}
}
}
@Override
protected URL findResource(String name) {
URL u = getParent().getResource(prefix + name);
if (u != null) {
try {
jars.add(new JarFile(new File(toJarUrl(u).toURI())));
} catch (URISyntaxException | IOException ex) {
Logger.getLogger(ParallelWorldClassLoader.class.getName()).log(Level.WARNING, null, ex);
} catch (ClassNotFoundException ex) {
//ignore - not a jar
}
}
return u;
}
@Override
protected Enumeration findResources(String name) throws IOException {
Enumeration en = getParent().getResources(prefix + name);
while (en.hasMoreElements()) {
try {
jars.add(new JarFile(new File(toJarUrl(en.nextElement()).toURI())));
} catch (URISyntaxException | IOException ex) {
//should not happen
Logger.getLogger(ParallelWorldClassLoader.class.getName()).log(Level.WARNING, null, ex);
} catch (ClassNotFoundException ex) {
//ignore - not a jar
}
}
return en;
}
@Override
public synchronized void close() throws IOException {
for (JarFile jar : jars) {
jar.close();
}
}
/**
* Given the URL inside jar, returns the URL to the jar itself.
* @param res Resource in a jar
* @return URL to the conaining jar file
* @throws java.lang.ClassNotFoundException if res does not denote jar URL
* @throws java.net.MalformedURLException if computed URL is invalid
*/
public static URL toJarUrl(URL res) throws ClassNotFoundException, MalformedURLException {
String url = res.toExternalForm();
if(!url.startsWith("jar:"))
throw new ClassNotFoundException("Loaded outside a jar "+url);
url = url.substring(4); // cut off jar:
url = url.substring(0,url.lastIndexOf('!')); // cut off everything after '!'
url = url.replaceAll(" ", "%20"); // support white spaces in path
return new URL(url);
}
}