package org.hibernate.bytecode;
import org.hibernate.bytecode.util.ByteCodeHelper;
import java.io.InputStream;
/**
* A specialized classloader which performs bytecode enhancement on class
* definitions as they are loaded into the classloader scope.
*
* @author Emmanuel Bernard
* @author Steve Ebersole
*/
public class InstrumentedClassLoader extends ClassLoader {
private ClassTransformer classTransformer;
public InstrumentedClassLoader(ClassLoader parent, ClassTransformer classTransformer) {
super( parent );
this.classTransformer = classTransformer;
}
public Class loadClass(String name) throws ClassNotFoundException {
if ( name.startsWith( "java." ) || classTransformer == null ) {
return getParent().loadClass( name );
}
Class c = findLoadedClass( name );
if ( c != null ) {
return c;
}
InputStream is = this.getResourceAsStream( name.replace( '.', '/' ) + ".class" );
if ( is == null ) {
throw new ClassNotFoundException( name + " not found" );
}
try {
byte[] originalBytecode = ByteCodeHelper.readByteCode( is );
byte[] transformedBytecode = classTransformer.transform( getParent(), name, null, null, originalBytecode );
if ( originalBytecode == transformedBytecode ) {
// no transformations took place, so handle it as we would a
// non-instrumented class
return getParent().loadClass( name );
}
else {
return defineClass( name, transformedBytecode, 0, transformedBytecode.length );
}
}
catch( Throwable t ) {
throw new ClassNotFoundException( name + " not found", t );
}
}
}
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