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/*
* 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.tuscany.sca.extension.helper.impl;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.net.URL;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import org.apache.tuscany.sca.core.ExtensionPointRegistry;
/**
* Discovers Activators in the classpath using the J2SE
* jar file extensions for Service Provider discovery
*/
public class DiscoveryUtils {
public static <T> List<T> discoverActivators(Class<T> activatorClass, ClassLoader classLoader, ExtensionPointRegistry registry) {
Set<Class> activatorClasses = getServiceClasses(classLoader, activatorClass);
List<T> activators = new ArrayList<T>();
for (Class<T> c : activatorClasses) {
try {
activators.add(c.cast(instantiateActivator(c, registry)));
} catch (Throwable e) {
e.printStackTrace(); // TODO: log
}
}
return activators;
}
static Object instantiateActivator(Class activator, ExtensionPointRegistry registry) {
Constructor[] cs = activator.getConstructors();
if (cs.length != 1) {
throw new RuntimeException("Activator must have only one constructors");
}
Class<?>[] paramTypes = cs[0].getParameterTypes();
Object[] extensions = new Object[paramTypes.length];
for (int i=0; i< paramTypes.length; i++) {
if ("org.apache.tuscany.sca.host.http.ServletHost".equals(paramTypes[i].getName())) {
extensions[i] = getServletHost(registry);
} else {
extensions[i] = registry.getExtensionPoint(paramTypes[i]);
}
}
try {
return cs[0].newInstance(extensions);
} catch (Exception e) {
throw new RuntimeException(e);
}
}
private static Object getServletHost(ExtensionPointRegistry registry) {
try {
Class<?> servletHostEPClass = Class.forName("org.apache.tuscany.sca.host.http.ServletHostExtensionPoint");
Object servletHostEP = registry.getExtensionPoint(servletHostEPClass);
Class<?> extensibleServletHost = Class.forName("org.apache.tuscany.sca.host.http.ExtensibleServletHost");
return extensibleServletHost.getConstructor(new Class[] {servletHostEPClass}).newInstance(servletHostEP);
} catch (ClassNotFoundException e) {
throw new RuntimeException(e);
} catch (IllegalArgumentException e) {
throw new RuntimeException(e);
} catch (SecurityException e) {
throw new RuntimeException(e);
} catch (InstantiationException e) {
throw new RuntimeException(e);
} catch (IllegalAccessException e) {
throw new RuntimeException(e);
} catch (InvocationTargetException e) {
throw new RuntimeException(e);
} catch (NoSuchMethodException e) {
throw new RuntimeException(e);
}
}
static Set<Class> getServiceClasses(ClassLoader classLoader, Class name) {
try {
Set<Class> set = new HashSet<Class>();
Enumeration<URL> urls = classLoader.getResources("META-INF/services/" + name.getName());
while (urls.hasMoreElements()) {
URL url = urls.nextElement();
Set<String> services = getServiceClassNames(url);
if (services != null) {
for (String className : services) {
try {
set.add(Class.forName(className, true, classLoader));
} catch (Throwable e) {
// TODO: log
}
}
}
}
return set;
} catch (IOException e) {
throw new RuntimeException(e);
}
}
static Set<String> getServiceClassNames(URL url) throws IOException {
Set<String> names = new HashSet<String>();
InputStream is = url.openStream();
BufferedReader reader = null;
try {
reader = new BufferedReader(new InputStreamReader(is));
while (true) {
String line = reader.readLine();
if (line == null) {
break;
}
line = line.trim();
if (!line.startsWith("#") && !"".equals(line)) {
names.add(line.trim());
}
}
} finally {
if (reader != null) {
reader.close();
}
if (is != null){
try {
is.close();
} catch( IOException ioe) {
//ignore
}
}
}
return names;
}
}
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