/*
* 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.tomcat.util.scan;
import java.io.IOException;
import java.io.InputStream;
import java.net.URL;
import java.util.jar.Manifest;
import org.apache.tomcat.Jar;
/**
* This class provides a wrapper around {@link Jar} that uses reference counting to close and re-create the wrapped
* {@link Jar} instance as required.
*/
public class ReferenceCountedJar implements Jar {
private final URL url;
private Jar wrappedJar;
private int referenceCount = 0;
public ReferenceCountedJar(URL url) throws IOException {
this.url = url;
open();
}
/*
* Note: Returns this instance so it can be used with try-with-resources
*/
private synchronized ReferenceCountedJar open() throws IOException {
if (wrappedJar == null) {
wrappedJar = JarFactory.newInstance(url);
}
referenceCount++;
return this;
}
@Override
public synchronized void close() {
referenceCount--;
if (referenceCount == 0) {
wrappedJar.close();
wrappedJar = null;
}
}
@Override
public URL getJarFileURL() {
return url;
}
@Override
public InputStream getInputStream(String name) throws IOException {
try (ReferenceCountedJar jar = open()) {
return jar.wrappedJar.getInputStream(name);
}
}
@Override
public long getLastModified(String name) throws IOException {
try (ReferenceCountedJar jar = open()) {
return jar.wrappedJar.getLastModified(name);
}
}
@Override
public boolean exists(String name) throws IOException {
try (ReferenceCountedJar jar = open()) {
return jar.wrappedJar.exists(name);
}
}
@Override
public void nextEntry() {
try (ReferenceCountedJar jar = open()) {
jar.wrappedJar.nextEntry();
} catch (IOException ioe) {
throw new IllegalStateException(ioe);
}
}
@Override
public String getEntryName() {
try (ReferenceCountedJar jar = open()) {
return jar.wrappedJar.getEntryName();
} catch (IOException ioe) {
throw new IllegalStateException(ioe);
}
}
@Override
public InputStream getEntryInputStream() throws IOException {
try (ReferenceCountedJar jar = open()) {
return jar.wrappedJar.getEntryInputStream();
}
}
@Override
public String getURL(String entry) {
try (ReferenceCountedJar jar = open()) {
return jar.wrappedJar.getURL(entry);
} catch (IOException ioe) {
throw new IllegalStateException(ioe);
}
}
@Override
public Manifest getManifest() throws IOException {
try (ReferenceCountedJar jar = open()) {
return jar.wrappedJar.getManifest();
}
}
@Override
public void reset() throws IOException {
try (ReferenceCountedJar jar = open()) {
jar.wrappedJar.reset();
}
}
}