/*
* 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.jclouds.logging.config;
import static com.google.common.collect.Sets.filter;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.util.Arrays;
import java.util.Set;
import javax.annotation.Resource;
import javax.inject.Inject;
import javax.inject.Named;
import org.jclouds.logging.Logger;
import org.jclouds.logging.Logger.LoggerFactory;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Predicate;
import com.google.common.collect.Sets;
import com.google.inject.ProvisionException;
import com.google.inject.TypeLiteral;
import com.google.inject.spi.InjectionListener;
import com.google.inject.spi.TypeEncounter;
import com.google.inject.spi.TypeListener;
/**
* TypeListener that will bind {@link org.jclouds.logging.Logger} to members annotated with
* {@link javax.annotation.Resource}
* <p/>
* This class is a TypeListener so that it can create a logger whose category is
* the same as the name of the injected instance's class.
* <p/>
* Note that this occurs post-object construction through
* {@link com.google.inject.Binder#bindListener}.
* <p/>
* Here's an example usage:
* <pre>
* class A {
* @Resource private Logger logger = Logger.NULL;
* }
* <p/>
* Injector i = Guice.createInjector(new AbstractModule() {
* @Override protected void configure() {
* bindListener(any(), new
* BindLoggersAnnotatedWithResource( new
* JDKLogger.JDKLoggerFactory()));
* }
* });
* <p/>
* A = i.getInstance(A.class);
* // A will now have a logger associated with it
* </pre>
*
* @author Adrian Cole
*/
public class BindLoggersAnnotatedWithResource implements TypeListener {
static class AssignLoggerToField<I> implements InjectionListener<I> {
private final Logger logger;
private final Field field;
AssignLoggerToField(Logger logger, Field field) {
this.logger = logger;
this.field = field;
}
public void afterInjection(I injectee) {
try {
field.setAccessible(true);
field.set(injectee, logger);
} catch (IllegalAccessException e) {
throw new ProvisionException(e.getMessage(), e);
}
}
}
static class LoggerFieldsAnnotatedWithResource implements
Predicate<Field> {
public boolean apply(Field from) {
Annotation inject = from.getAnnotation(Resource.class);
return inject != null && from.getType().isAssignableFrom(Logger.class);
}
}
private final LoggerFactory loggerFactory;
@Inject
public BindLoggersAnnotatedWithResource(LoggerFactory loggerFactory) {
this.loggerFactory = loggerFactory;
}
public <I> void hear(TypeLiteral<I> injectableType,
TypeEncounter<I> encounter) {
Class<? super I> type = injectableType.getRawType();
Set<Field> loggerFields = getLoggerFieldsAnnotatedWithResource(type);
if (loggerFields.size() == 0)
return;
Logger logger = loggerFactory.getLogger(type.getName());
for (Field field : loggerFields) {
if (field.isAnnotationPresent(Named.class)){
Named name = field.getAnnotation(Named.class);
encounter.register(new AssignLoggerToField<I>(loggerFactory.getLogger(name.value()), field));
} else {
encounter.register(new AssignLoggerToField<I>(logger, field));
}
}
}
@VisibleForTesting
Set<Field> getLoggerFieldsAnnotatedWithResource(Class<?> declaredType) {
Set<Field> fields = Sets.newHashSet();
Class<?> type = declaredType;
while (type != null) {
fields.addAll(Arrays.asList(type.getDeclaredFields()));
type = type.getSuperclass();
}
return filter(fields, new LoggerFieldsAnnotatedWithResource());
}
}