Hibernate example source code file (InstrumentedClassLoader.java)

This example Hibernate source code file (InstrumentedClassLoader.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Hibernate tags/keywords

class, class, classloader, classnotfoundexception, classnotfoundexception, illegalclassformatexception, inputstream, instrumentedclassloader, instrumentedclassloader, interceptfieldclassfiletransformer, io, ioexception, ioexception, list, override, util

The Hibernate InstrumentedClassLoader.java source code

//$Id$
package org.hibernate.ejb.test.instrument;
import java.io.IOException;
import java.io.InputStream;
import java.lang.instrument.IllegalClassFormatException;
import java.util.List;
import org.hibernate.ejb.instrument.InterceptFieldClassFileTransformer;

/**
 * @author Emmanuel Bernard
 */
public class InstrumentedClassLoader extends ClassLoader {
	private List<String> entities;

	public InstrumentedClassLoader(ClassLoader parent) {
		super( parent );
	}

	@Override
	public Class<?> loadClass(String name) throws ClassNotFoundException {
		if ( name != null && name.startsWith( "java.lang." ) ) 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 );
		byte[] buffer = new byte[409600];
		byte[] originalClass = new byte[0];
		int r = 0;
		try {
			r = is.read( buffer );
		}
		catch (IOException e) {
			throw new ClassNotFoundException( name + " not found", e );
		}
		while ( r >= buffer.length ) {
			byte[] temp = new byte[ originalClass.length + buffer.length ];
			System.arraycopy( originalClass, 0, temp, 0, originalClass.length );
			System.arraycopy( buffer, 0, temp, originalClass.length, buffer.length );
			originalClass = temp;
		}
		if ( r != -1 ) {
			byte[] temp = new byte[ originalClass.length + r ];
			System.arraycopy( originalClass, 0, temp, 0, originalClass.length );
			System.arraycopy( buffer, 0, temp, originalClass.length, r );
			originalClass = temp;
		}
		try {
			is.close();
		}
		catch (IOException e) {
			throw new ClassNotFoundException( name + " not found", e );
		}
		InterceptFieldClassFileTransformer t = new InterceptFieldClassFileTransformer( entities );
		byte[] transformed = new byte[0];
		try {
			transformed = t.transform(
					getParent(),
					name,
					null,
					null,
					originalClass
			);
		}
		catch (IllegalClassFormatException e) {
			throw new ClassNotFoundException( name + " not found", e );
		}

		return defineClass( name, transformed, 0, transformed.length );
	}

	public void setEntities(List<String> entities) {
		this.entities = entities;
	}
}