//$Id: PojoInstantiator.java 9210 2006-02-03 22:15:19Z steveebersole $
package org.hibernate.tuple;
import java.io.IOException;
import java.io.Serializable;
import java.lang.reflect.Constructor;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.InstantiationException;
import org.hibernate.PropertyNotFoundException;
import org.hibernate.bytecode.ReflectionOptimizer;
import org.hibernate.mapping.PersistentClass;
import org.hibernate.mapping.Component;
import org.hibernate.util.ReflectHelper;
/**
* Defines a POJO-based instantiator for use from the tuplizers.
*/
public class PojoInstantiator implements Instantiator, Serializable {
private static final Log log = LogFactory.getLog(PojoInstantiator.class);
private transient Constructor constructor;
private final Class mappedClass;
private final transient ReflectionOptimizer.InstantiationOptimizer optimizer;
private final boolean embeddedIdentifier;
private final Class proxyInterface;
public PojoInstantiator(Component component, ReflectionOptimizer.InstantiationOptimizer optimizer) {
this.mappedClass = component.getComponentClass();
this.optimizer = optimizer;
this.proxyInterface = null;
this.embeddedIdentifier = false;
try {
constructor = ReflectHelper.getDefaultConstructor(mappedClass);
}
catch ( PropertyNotFoundException pnfe ) {
log.info(
"no default (no-argument) constructor for class: " +
mappedClass.getName() +
" (class must be instantiated by Interceptor)"
);
constructor = null;
}
}
public PojoInstantiator(PersistentClass persistentClass, ReflectionOptimizer.InstantiationOptimizer optimizer) {
this.mappedClass = persistentClass.getMappedClass();
this.proxyInterface = persistentClass.getProxyInterface();
this.embeddedIdentifier = persistentClass.hasEmbeddedIdentifier();
this.optimizer = optimizer;
try {
constructor = ReflectHelper.getDefaultConstructor( mappedClass );
}
catch ( PropertyNotFoundException pnfe ) {
log.info(
"no default (no-argument) constructor for class: " +
mappedClass.getName() +
" (class must be instantiated by Interceptor)"
);
constructor = null;
}
}
private void readObject(java.io.ObjectInputStream stream)
throws ClassNotFoundException, IOException {
stream.defaultReadObject();
constructor = ReflectHelper.getDefaultConstructor(mappedClass);
}
public Object instantiate() {
if ( ReflectHelper.isAbstractClass(mappedClass) ) {
throw new InstantiationException( "Cannot instantiate abstract class or interface: ", mappedClass );
}
else if ( optimizer != null ) {
return optimizer.newInstance();
}
else if ( constructor == null ) {
throw new InstantiationException( "No default constructor for entity: ", mappedClass );
}
else {
try {
return constructor.newInstance( null );
}
catch ( Exception e ) {
throw new InstantiationException( "Could not instantiate entity: ", mappedClass, e );
}
}
}
public Object instantiate(Serializable id) {
final boolean useEmbeddedIdentifierInstanceAsEntity = embeddedIdentifier &&
id != null &&
id.getClass().equals(mappedClass);
return useEmbeddedIdentifierInstanceAsEntity ? id : instantiate();
}
public boolean isInstance(Object object) {
return mappedClass.isInstance(object) ||
( proxyInterface!=null && proxyInterface.isInstance(object) ); //this one needed only for guessEntityMode()
}
}