/* * Javassist, a Java-bytecode translator toolkit. * Copyright (C) 1999- Shigeru Chiba. All Rights Reserved. * * The contents of this file are subject to the Mozilla Public License Version * 1.1 (the "License"); you may not use this file except in compliance with * the License. Alternatively, the contents of this file may be used under * the terms of the GNU Lesser General Public License Version 2.1 or later, * or the Apache License Version 2.0. * * Software distributed under the License is distributed on an "AS IS" basis, * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License * for the specific language governing rights and limitations under the * License. */ package javassist; import java.io.InputStream; import java.net.URL; import java.lang.ref.WeakReference; /** * A class search-path representing a class loader. * *
It is used for obtaining a class file from the given
* class loader by getResourceAsStream()
.
* The LoaderClassPath
refers to the class loader through
* WeakReference
. If the class loader is garbage collected,
* the other search pathes are examined.
*
*
The given class loader must have both getResourceAsStream()
* and getResource()
.
*
*
Class files in a named module are private to that module. * This method cannot obtain class files in named modules. *
* * @author Bill Burke * @author Shigeru Chiba * * @see ClassPool#insertClassPath(ClassPath) * @see ClassPool#appendClassPath(ClassPath) * @see ClassClassPath * @see ModuleClassPath */ public class LoaderClassPath implements ClassPath { private WeakReference clref; /** * If true, this search path implicitly includes * a {@code ModuleClassPath} as a fallback. * For backward compatibility, this field is set to true * if the JVM is Java 9 or later. It can be false in * Java 9 but the behavior of {@code LoadClassPath} will * be different from its behavior in Java 8 or older. * *This field must be false if the JVM is Java 8 or older.
*
* @since 3.21
*/
public static boolean fallbackOnModuleClassPath
= javassist.bytecode.ClassFile.MAJOR_VERSION >= javassist.bytecode.ClassFile.JAVA_9;
private static ModuleClassPath moduleClassPath = null;
private boolean doFallback;
/**
* Creates a search path representing a class loader.
*/
public LoaderClassPath(ClassLoader cl) {
this(cl, fallbackOnModuleClassPath);
}
LoaderClassPath(ClassLoader cl, boolean fallback) {
clref = new WeakReference(cl);
doFallback = fallback;
if (fallback)
synchronized (LoaderClassPath.class) {
if (moduleClassPath == null)
moduleClassPath = new ModuleClassPath();
}
}
public String toString() {
Object cl = null;
if (clref != null)
cl = clref.get();
return cl == null ? "getResourceAsStream(String)
* on the class loader.
*/
public InputStream openClassfile(String classname) throws NotFoundException {
String cname = classname.replace('.', '/') + ".class";
ClassLoader cl = (ClassLoader)clref.get();
if (cl == null)
return null; // not found
else {
InputStream is = cl.getResourceAsStream(cname);
if (is == null && doFallback)
return moduleClassPath.openClassfile(classname);
else
return is;
}
}
/**
* Obtains the URL of the specified class file.
* This method calls getResource(String)
* on the class loader.
*
* @return null if the class file could not be found.
*/
public URL find(String classname) {
String cname = classname.replace('.', '/') + ".class";
ClassLoader cl = (ClassLoader)clref.get();
if (cl == null)
return null; // not found
else {
URL url = cl.getResource(cname);
if (url == null && doFallback)
return moduleClassPath.find(classname);
else
return url;
}
}
/**
* Closes this class path.
*/
public void close() {
clref = null;
}
}