org.jvnet.hk2.internal.ProxyUtilities Maven / Gradle / Ivy
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package org.jvnet.hk2.internal;
import java.lang.reflect.Proxy;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.WeakHashMap;
import org.glassfish.hk2.api.ActiveDescriptor;
import org.glassfish.hk2.api.MultiException;
import org.glassfish.hk2.api.ProxyCtl;
import org.glassfish.hk2.api.ServiceHandle;
import javassist.util.proxy.MethodHandler;
import javassist.util.proxy.ProxyFactory;
import javassist.util.proxy.ProxyObject;
/**
* Utilities around proxying
*
* @author jwells
*
*/
public class ProxyUtilities {
private final static Object proxyCreationLock = new Object();
private final static WeakHashMap delegatingLoaderSet =
new WeakHashMap();
private static T secureCreate(final Class superclass,
final Class[] interfaces,
final MethodHandler callback,
boolean useJDKProxy) {
/* construct the classloader where the generated proxy will be created --
* this classloader must have visibility into the javaassist classloader as well as
* the superclass' classloader
*/
ClassLoader myLoader;
synchronized (delegatingLoaderSet) {
WeakDelegatingCacheEntry key = new WeakDelegatingCacheEntry(superclass.getClassLoader());
WeakDelegatingCacheEntry found = null;
for (WeakDelegatingCacheEntry entry : delegatingLoaderSet.keySet()) {
if (key.equals(entry)) {
found = entry;
break;
}
}
if (found == null) {
found = key;
delegatingLoaderSet.put(found, null);
}
myLoader = found.getDelegator();
}
final ClassLoader delegatingLoader = myLoader;
if (useJDKProxy) {
return AccessController.doPrivileged(new PrivilegedAction() {
@SuppressWarnings("unchecked")
@Override
public T run() {
return (T) Proxy.newProxyInstance(delegatingLoader, interfaces,
new MethodInterceptorInvocationHandler(callback));
}
});
}
return AccessController.doPrivileged(new PrivilegedAction() {
@SuppressWarnings("unchecked")
@Override
public T run() {
synchronized (proxyCreationLock) {
ProxyFactory.ClassLoaderProvider originalProvider = ProxyFactory.classLoaderProvider;
ProxyFactory.classLoaderProvider = new ProxyFactory.ClassLoaderProvider() {
@Override
public ClassLoader get(ProxyFactory arg0) {
return delegatingLoader;
}
};
try {
ProxyFactory proxyFactory = new ProxyFactory();
proxyFactory.setInterfaces(interfaces);
proxyFactory.setSuperclass(superclass);
Class proxyClass = proxyFactory.createClass();
try {
T proxy = (T) proxyClass.newInstance();
((ProxyObject) proxy).setHandler(callback);
return proxy;
} catch (Exception e1) {
throw new RuntimeException(e1);
}
}
finally {
ProxyFactory.classLoaderProvider = originalProvider;
}
}
}
});
}
@SuppressWarnings("unchecked")
public static T generateProxy(Class requestedClass,
ServiceLocatorImpl locator,
ActiveDescriptor root,
ServiceHandle handle) {
boolean isInterface = (requestedClass == null) ? false : requestedClass.isInterface() ;
final Class proxyClass;
Class iFaces[];
if (isInterface) {
proxyClass = requestedClass;
iFaces = new Class[2];
iFaces[0] = proxyClass;
iFaces[1] = ProxyCtl.class;
}
else {
proxyClass = Utilities.getFactoryAwareImplementationClass(root);
iFaces = Utilities.getInterfacesForProxy(root.getContractTypes());
}
T proxy;
try {
proxy = (T) secureCreate(proxyClass,
iFaces,
new MethodInterceptorImpl(locator, root, handle),
isInterface);
}
catch (Throwable th) {
Exception addMe = new IllegalArgumentException("While attempting to create a Proxy for " + proxyClass.getName() +
" in proxiable scope " + root.getScope() + " an error occured while creating the proxy");
if (th instanceof MultiException) {
MultiException me = (MultiException) th;
me.addError(addMe);
throw me;
}
MultiException me = new MultiException(th);
me.addError(addMe);
throw me;
}
return proxy;
}
/**
* The point of this class is to reside in a WeakHashMap as the
* key and thus only have weak references to the classloaders
* pointed to by this object. It also reduces the number of
* classloaders that are created by calculating the DelegatingClassLoader
* only once, though the performance benefit of that is probably
* out-weighed by the fact that we have to linearly go through
* the WeakHashMap keys to get back the original key object
*
* @author jwells
*
*/
private static class WeakDelegatingCacheEntry {
private final ClassLoader key;
private DelegatingClassLoader loader;
private WeakDelegatingCacheEntry(ClassLoader key) {
this.key = key;
}
private DelegatingClassLoader getDelegator() {
if (loader != null) return loader;
final Object backPointer = this;
loader = AccessController
.doPrivileged(new PrivilegedAction() {
@Override
public DelegatingClassLoader run() {
// create a delegating classloader that attempts to
// load from the superclass' classloader first,
// then hk2-locator's classloader second.
return new DelegatingClassLoader(
key,
backPointer,
ProxyFactory.class.getClassLoader(),
ProxyCtl.class.getClassLoader());
}
});
return loader;
}
@Override
public int hashCode() {
return key.hashCode();
}
@Override
public boolean equals(Object o) {
if (o == null) return false;
if (!(o instanceof WeakDelegatingCacheEntry)) return false;
WeakDelegatingCacheEntry other = (WeakDelegatingCacheEntry) o;
return key.equals(other.key);
}
}
}
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