/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.apache.tools.ant.types.resources;
import java.io.FilterInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.Stack;
import org.apache.tools.ant.AntClassLoader;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.types.Path;
import org.apache.tools.ant.types.Reference;
import org.apache.tools.ant.types.Resource;
import org.apache.tools.ant.util.FileUtils;
/**
*
* A Resource representation of anything that is accessed via a Java classloader.
* The core methods to set/resolve the classpath are provided.
* @since Ant 1.8.0
*
*/
public abstract class AbstractClasspathResource extends Resource {
private Path classpath;
private Reference loader;
private boolean parentFirst = true;
/**
* Set the classpath to use when looking up a resource.
* @param classpath to add to any existing classpath
*/
public void setClasspath(Path classpath) {
checkAttributesAllowed();
if (this.classpath == null) {
this.classpath = classpath;
} else {
this.classpath.append(classpath);
}
setChecked(false);
}
/**
* Add a classpath to use when looking up a resource.
* @return The classpath to be configured
*/
public Path createClasspath() {
checkChildrenAllowed();
if (classpath == null) {
classpath = new Path(getProject());
}
setChecked(false);
return classpath.createPath();
}
/**
* Set the classpath to use when looking up a resource,
* given as reference to a <path> defined elsewhere
* @param r The reference value
*/
public void setClasspathRef(Reference r) {
checkAttributesAllowed();
createClasspath().setRefid(r);
}
/**
* get the classpath used by this <code>LoadProperties</code>.
* @return The classpath
*/
public Path getClasspath() {
if (isReference()) {
return ((AbstractClasspathResource) getCheckedRef()).getClasspath();
}
dieOnCircularReference();
return classpath;
}
/**
* Get the loader.
* @return the loader.
*/
public Reference getLoader() {
if (isReference()) {
return ((AbstractClasspathResource) getCheckedRef()).getLoader();
}
dieOnCircularReference();
return loader;
}
/**
* Use the reference to locate the loader. If the loader is not
* found, taskdef will use the specified classpath and register it
* with the specified name.
*
* This allow multiple taskdef/typedef to use the same class loader,
* so they can be used together. It eliminate the need to
* put them in the CLASSPATH.
*
* @param r the reference to locate the loader.
*/
public void setLoaderRef(Reference r) {
checkAttributesAllowed();
loader = r;
}
/**
* Whether to consult the parent classloader first.
*
* <p>Only relevant if a classpath has been specified.</p>
*
* @since Ant 1.8.0
*/
public void setParentFirst(boolean b) {
parentFirst = b;
}
/**
* Overrides the super version.
* @param r the Reference to set.
*/
public void setRefid(Reference r) {
if (loader != null || classpath != null) {
throw tooManyAttributes();
}
super.setRefid(r);
}
/**
* Learn whether this resource exists. This implementation opens the input stream
* as the test.
* @return true if this resource exists.
*/
public boolean isExists() {
if (isReference()) {
return ((Resource) getCheckedRef()).isExists();
}
dieOnCircularReference();
try (InputStream is = getInputStream()) {
return is != null;
} catch (IOException ex) {
return false;
}
}
/**
* Return an InputStream for reading the contents of this Resource.
* @return an InputStream object.
* @throws IOException if an error occurs.
*/
public InputStream getInputStream() throws IOException {
if (isReference()) {
return ((Resource) getCheckedRef()).getInputStream();
}
dieOnCircularReference();
final ClassLoaderWithFlag classLoader = getClassLoader();
return !classLoader.needsCleanup()
? openInputStream(classLoader.getLoader())
: new FilterInputStream(openInputStream(classLoader.getLoader())) {
@Override
public void close() throws IOException {
FileUtils.close(in);
classLoader.cleanup();
}
@Override
protected void finalize() throws Throwable {
try {
close();
} finally {
super.finalize();
}
}
};
}
/**
* combines the various ways that could specify a ClassLoader and
* potentially creates one that needs to be cleaned up when it is
* no longer needed so that classes can get garbage collected.
*/
protected ClassLoaderWithFlag getClassLoader() {
ClassLoader cl = null;
if (loader != null) {
cl = (ClassLoader) loader.getReferencedObject();
}
boolean clNeedsCleanup = false;
if (cl == null) {
if (getClasspath() != null) {
Path p = getClasspath().concatSystemClasspath("ignore");
if (parentFirst) {
cl = getProject().createClassLoader(p);
} else {
cl = AntClassLoader.newAntClassLoader(getProject()
.getCoreLoader(),
getProject(),
p, false);
}
clNeedsCleanup = loader == null;
} else {
cl = JavaResource.class.getClassLoader();
}
if (loader != null && cl != null) {
getProject().addReference(loader.getRefId(), cl);
}
}
return new ClassLoaderWithFlag(cl, clNeedsCleanup);
}
/**
* open the input stream from a specific classloader
* @param cl the classloader to use. Will be null if the system classloader is used
* @return an open input stream for the resource
* @throws IOException if an error occurs.
*/
protected abstract InputStream openInputStream(ClassLoader cl) throws IOException;
protected synchronized void dieOnCircularReference(Stack<Object> stk, Project p) {
if (isChecked()) {
return;
}
if (isReference()) {
super.dieOnCircularReference(stk, p);
} else {
if (classpath != null) {
pushAndInvokeCircularReferenceCheck(classpath, stk, p);
}
setChecked(true);
}
}
public static class ClassLoaderWithFlag {
private final ClassLoader loader;
private final boolean cleanup;
ClassLoaderWithFlag(ClassLoader l, boolean needsCleanup) {
loader = l;
cleanup = needsCleanup && l instanceof AntClassLoader;
}
public ClassLoader getLoader() {
return loader;
}
public boolean needsCleanup() {
return cleanup;
}
public void cleanup() {
if (cleanup) {
((AntClassLoader) loader).cleanup();
}
}
}
}