/*
* The MIT License
*
* Copyright (c) 2004-2009, Sun Microsystems, Inc., Kohsuke Kawaguchi
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package hudson.util;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.Collection;
import java.util.Enumeration;
import java.util.List;
import java.util.ArrayList;
import java.util.logging.Level;
import java.util.logging.Logger;
import static java.util.logging.Level.WARNING;
/**
* Load classes by looking up <tt>META-INF/services</tt>.
*
* @author Kohsuke Kawaguchi
*/
public class Service {
/**
* Poorman's clone of JDK6 ServiceLoader.
*/
public static <T> List<T> loadInstances(ClassLoader classLoader, Class<T> type) throws IOException {
List<T> result = new ArrayList<T>();
final Enumeration<URL> e = classLoader.getResources("META-INF/services/"+type.getName());
while (e.hasMoreElements()) {
URL url = e.nextElement();
BufferedReader configFile = new BufferedReader(new InputStreamReader(url.openStream(),"UTF-8"));
String line;
while ((line = configFile.readLine()) != null) {
line = line.trim();
if (line.startsWith("#") || line.length()==0) continue;
try {
Class<?> t = classLoader.loadClass(line);
if (!type.isAssignableFrom(t)) continue; // invalid type
result.add(type.cast(t.newInstance()));
} catch (ClassNotFoundException x) {
LOGGER.log(WARNING,"Failed to load "+line,x);
} catch (InstantiationException x) {
LOGGER.log(WARNING,"Failed to load "+line,x);
} catch (IllegalAccessException x) {
LOGGER.log(WARNING,"Failed to load "+line,x);
}
}
}
return result;
}
/**
* Look up <tt>META-INF/service/<i>SPICLASSNAME</i></tt> from the classloader
* and all the discovered classes into the given collection.
*/
public static <T> void load(Class<T> spi, ClassLoader cl, Collection<Class<? extends T>> result) {
try {
Enumeration<URL> e = cl.getResources("META-INF/services/" + spi.getName());
while(e.hasMoreElements()) {
BufferedReader r = null;
URL url = e.nextElement();
try {
r = new BufferedReader(new InputStreamReader(url.openStream(),"UTF-8"));
String line;
while((line=r.readLine())!=null) {
if(line.startsWith("#"))
continue; // comment line
line = line.trim();
if(line.length()==0)
continue; // empty line. ignore.
try {
result.add(cl.loadClass(line).asSubclass(spi));
} catch (ClassNotFoundException x) {
LOGGER.log(Level.WARNING, "Failed to load "+line, x);
}
}
} catch (IOException x) {
LOGGER.log(Level.WARNING, "Failed to load "+url, x);
} finally {
r.close();
}
}
} catch (IOException x) {
LOGGER.log(Level.WARNING, "Failed to look up service providers for "+spi, x);
}
}
private static final Logger LOGGER = Logger.getLogger(Service.class.getName());
}