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package com.sun.hk2.component;
import org.jvnet.hk2.component.ComponentException;
import org.jvnet.hk2.component.Creator;
import org.jvnet.hk2.component.Creators;
import org.jvnet.hk2.component.Habitat;
import org.jvnet.hk2.component.Inhabitant;
import org.jvnet.hk2.component.MultiMap;
/**
* @author Kohsuke Kawaguchi
*/
public class LazyInhabitant<T> extends EventPublishingInhabitant<T> implements ClassLoaderHolder {
private final String typeName;
/**
* Lazy reference to {@link ClassLoader}.
*/
private final Holder<ClassLoader> classLoader;
protected final Habitat habitat;
private final MultiMap<String,String> metadata;
private final Inhabitant<?> lead;
public LazyInhabitant(Habitat habitat, Holder<ClassLoader> cl, String typeName, MultiMap<String,String> metadata) {
this(habitat, cl, typeName, metadata, null);
}
public LazyInhabitant(Habitat habitat, Holder<ClassLoader> cl, String typeName, MultiMap<String,String> metadata, Inhabitant<?> lead) {
assert metadata!=null;
this.habitat = habitat;
this.classLoader = cl;
this.typeName = typeName;
this.metadata = metadata;
this.lead = lead;
}
@Override
public Inhabitant<?> lead() {
return lead;
}
@Override
public String typeName() {
return typeName;
}
@Override
public Class<T> type() {
// fetching is too heavy of an operation because it will activate/write the class
// fetch();
Inhabitant<T> real = this.real;
if (null != real) {
return real.type();
} else {
return loadClass();
}
}
@Override
public MultiMap<String,String> metadata() {
return metadata;
}
@Override
protected synchronized void fetch() {
if (null == real) {
Class<T> c = loadClass();
real = Inhabitants.wrapByScope(c,createCreator(c),habitat);
}
}
public final ClassLoader getClassLoader() {
return classLoader.get();
}
@SuppressWarnings("unchecked")
protected Class<T> loadClass() {
final ClassLoader cl = getClassLoader();
try {
Class<T> c = (Class<T>) cl.loadClass(typeName);
return c;
} catch (ClassNotFoundException e) {
throw new ComponentException("Failed to load "+typeName+" from " + cl, e);
}
}
@Override
public synchronized void release() {
super.release();
real = null;
}
/**
* Creates {@link Creator} for instantiating objects.
*/
protected Creator<T> createCreator(Class<T> c) {
return Creators.create(c,habitat,metadata);
}
}