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/*
* Copyright © 2009 Reinier Zwitserloot and Roel Spilker.
*
* 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 lombok.core;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.lang.annotation.Annotation;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.net.URL;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.Set;
import lombok.Lombok;
/**
* The java core libraries have a SPI discovery system, but it works only in Java 1.6 and up. For at least Eclipse,
* lombok actually works in java 1.5, so we've rolled our own SPI discovery system.
*
* It is not API compatible with <code>ServiceLoader</code>.
*
* @see java.util.ServiceLoader
*/
public class SpiLoadUtil {
private SpiLoadUtil() {
//Prevent instantiation
}
/**
* Returns an iterator of instances that, at least according to the spi discovery file, are implementations
* of the stated class.
*
* Like ServiceLoader, each listed class is turned into an instance by calling the public no-args constructor.
*
* Convenience method that calls the more elaborate {@link #findServices(Class, ClassLoader)} method with
* this {@link java.lang.Thread}'s context class loader as <code>ClassLoader</code>.
*
* @param target class to find implementations for.
*/
public static <C> Iterator<C> findServices(Class<C> target) throws IOException {
return findServices(target, Thread.currentThread().getContextClassLoader());
}
/**
* Returns an iterator of class objects that, at least according to the spi discovery file, are implementations
* of the stated class.
*
* Like ServiceLoader, each listed class is turned into an instance by calling the public no-args constructor.
*
* @param target class to find implementations for.
* @param loader The classloader object to use to both the spi discovery files, as well as the loader to use
* to make the returned instances.
*/
public static <C> Iterator<C> findServices(final Class<C> target, final ClassLoader loader) throws IOException {
Enumeration<URL> resources = loader.getResources("META-INF/services/" + target.getName());
final Set<String> entries = new LinkedHashSet<String>();
while ( resources.hasMoreElements() ) {
URL url = resources.nextElement();
readServicesFromUrl(entries, url);
}
final Iterator<String> names = entries.iterator();
return new Iterator<C>() {
public boolean hasNext() {
return names.hasNext();
}
public C next() {
try {
return target.cast(Class.forName(names.next(), true, loader).newInstance());
} catch ( Throwable t ) {
throw Lombok.sneakyThrow(t);
}
}
public void remove() {
throw new UnsupportedOperationException();
}
};
}
private static void readServicesFromUrl(Collection<String> list, URL url) throws IOException {
InputStream in = url.openStream();
try {
if ( in == null ) return;
BufferedReader r = new BufferedReader(new InputStreamReader(in, "UTF-8"));
while ( true ) {
String line = r.readLine();
if ( line == null ) break;
int idx = line.indexOf('#');
if ( idx != -1 ) line = line.substring(0, idx);
line = line.trim();
if ( line.length() == 0 ) continue;
list.add(line);
}
} finally {
try { in.close(); } catch ( Throwable ignore ) {}
}
}
/**
* This method will find the <code>T</code> in <code>public class Foo extends BaseType<T>.
*
* It returns an annotation type because it is used exclusively to figure out which annotations are
* being handled by {@link lombok.eclipse.EclipseAnnotationHandler} and {@link lombok.javac.JavacAnnotationHandler}.
*/
@SuppressWarnings("unchecked")
public static Class<? extends Annotation> findAnnotationClass(Class<?> c, Class<?> base) {
if ( c == Object.class || c == null ) return null;
for ( Type iface : c.getGenericInterfaces() ) {
if ( iface instanceof ParameterizedType ) {
ParameterizedType p = (ParameterizedType)iface;
if ( !base.equals(p.getRawType()) ) continue;
Type target = p.getActualTypeArguments()[0];
if ( target instanceof Class<?> ) {
if ( Annotation.class.isAssignableFrom((Class<?>) target) ) {
return (Class<? extends Annotation>) target;
}
}
throw new ClassCastException("Not an annotation type: " + target);
}
}
Class<? extends Annotation> potential = findAnnotationClass(c.getSuperclass(), base);
if ( potential != null ) return potential;
for ( Class<?> iface : c.getInterfaces() ) {
potential = findAnnotationClass(iface, base);
if ( potential != null ) return potential;
}
return null;
}
}
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