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Spice up your java: Automatic Resource Management, automatic generation of getters, setters, equals, hashCode and toString, and more!
/*
* Copyright (C) 2009-2011 The Project Lombok Authors.
*
* 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.ArrayList;
import java.util.Collection;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Set;
/**
* 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}.
*
* @see java.util.ServiceLoader
*/
public class SpiLoadUtil {
private SpiLoadUtil() {
//Prevent instantiation
}
/**
* Method that conveniently turn the {@code Iterable}s returned by the other methods in this class to a
* {@code List}.
*
* @see #findServices(Class)
* @see #findServices(Class, ClassLoader)
*/
public static List readAllFromIterator(Iterable findServices) {
List list = new ArrayList();
for (T t : findServices) list.add(t);
return list;
}
/**
* 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}.
*
* @param target class to find implementations for.
*/
public static Iterable findServices(Class 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 Iterable findServices(final Class target, ClassLoader loader) throws IOException {
if (loader == null) loader = ClassLoader.getSystemClassLoader();
Enumeration resources = loader.getResources("META-INF/services/" + target.getName());
final Set entries = new LinkedHashSet();
while (resources.hasMoreElements()) {
URL url = resources.nextElement();
readServicesFromUrl(entries, url);
}
final Iterator names = entries.iterator();
final ClassLoader fLoader = loader;
return new Iterable () {
@Override public Iterator iterator() {
return new Iterator() {
@Override public boolean hasNext() {
return names.hasNext();
}
@Override public C next() {
try {
return target.cast(Class.forName(names.next(), true, fLoader).newInstance());
} catch (Exception e) {
if (e instanceof RuntimeException) throw (RuntimeException)e;
throw new RuntimeException(e);
}
}
@Override public void remove() {
throw new UnsupportedOperationException();
}
};
}
};
}
private static void readServicesFromUrl(Collection 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 {
if (in != null) in.close();
} catch (Throwable ignore) {}
}
}
/**
* This method will find the @{code T} in {@code public class Foo extends BaseType}.
*
* 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}.
*/
public static Class findAnnotationClass(Class c, Class base) {
if (c == Object.class || c == null) return null;
Class answer = null;
answer = findAnnotationHelper(base, c.getGenericSuperclass());
if (answer != null) return answer;
for (Type iface : c.getGenericInterfaces()) {
answer = findAnnotationHelper(base, iface);
if (answer != null) return answer;
}
Class 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;
}
@SuppressWarnings("unchecked")
private static Class findAnnotationHelper(Class base, Type iface) {
if (iface instanceof ParameterizedType) {
ParameterizedType p = (ParameterizedType)iface;
if (!base.equals(p.getRawType())) return null;
Type target = p.getActualTypeArguments()[0];
if (target instanceof Class) {
if (Annotation.class.isAssignableFrom((Class) target)) {
return (Class) target;
}
}
throw new ClassCastException("Not an annotation type: " + target);
}
return null;
}
}