org.jruby.embed.jsr223.ServiceFinder Maven / Gradle / Ivy
/**
* **** BEGIN LICENSE BLOCK *****
* Version: CPL 1.0/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Common Public
* License Version 1.0 (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.eclipse.org/legal/cpl-v10.html
*
* 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.
*
* Copyright (C) 2009 Yoko Harada
*
* Alternatively, the contents of this file may be used under the terms of
* either of the GNU General Public License Version 2 or later (the "GPL"),
* or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the CPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the CPL, the GPL or the LGPL.
* **** END LICENSE BLOCK *****
*/
package org.jruby.embed.jsr223;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.List;
import java.util.StringTokenizer;
/**
* Finds SPI based services from classpath.
*
* @author Yoko Harada
*/
class ServiceFinder {
private ClassLoader loader = null;
private String serviceName;
private HashSet services;
ServiceFinder(ClassLoader loader, String serviceName) throws IOException {
this.serviceName = serviceName;
Enumeration urls = findResources(loader);
List classNames = getClassNames(urls);
services = instantiateClasses(classNames);
}
HashSet getServices() {
return services;
}
private Enumeration findResources(ClassLoader loader) throws IOException {
Enumeration urls;
if (loader == null) {
this.loader = ClassLoader.getSystemClassLoader();
urls = ClassLoader.getSystemResources(serviceName);
} else {
this.loader = loader;
urls = loader.getResources(serviceName);
}
return urls;
}
private List getClassNames(Enumeration urls) {
String encoding = System.getProperty("file.encoding");
List names = new ArrayList();
URL url = null;
while (urls.hasMoreElements()) {
try {
url = urls.nextElement();
BufferedReader reader =
new BufferedReader(new InputStreamReader(url.openStream(), encoding));
String line;
while ((line = reader.readLine()) != null) {
if ((line = deleteComments(line)) != null) {
names.add(line);
}
}
} catch (IOException e) {
System.err.println("Failed to get a class name from " + url.toString());
continue;
}
}
return names;
}
private String deleteComments(String line) {
if (line.startsWith("#")) {
return null;
}
if (line.length() < 1) {
return null;
}
StringTokenizer st = new StringTokenizer(line, "#");
return ((String) st.nextElement()).trim();
}
private HashSet instantiateClasses(List names) {
HashSet instances = new HashSet();
for (String name : names) {
try {
Class clazz = Class.forName(name, true, loader);
T instance = (T) clazz.newInstance();
instances.add(instance);
} catch (ClassNotFoundException e) {
System.err.println(name + " was not found");
continue;
} catch (InstantiationException e) {
System.err.println(name + " was not instantiated");
continue;
} catch (IllegalAccessException e) {
System.err.println(name + " committed illegal access");
continue;
} catch (Throwable e) {
System.err.println("failed to instantiate " + name);
continue;
}
}
return instances;
}
}