de.thksystems.persistence.hibernate.immutable.ImmutableCheckInterceptor Maven / Gradle / Ivy
/*
* tksCommons / mugwort
*
* Author : Thomas Kuhlmann (ThK-Systems, http://oss.thk-systems.de) License : LGPL (https://www.gnu.org/licenses/lgpl.html)
*/
package de.thksystems.persistence.hibernate.immutable;
import java.io.Serializable;
import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.util.Date;
import org.hibernate.EmptyInterceptor;
import org.hibernate.type.Type;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.util.ReflectionUtils;
/**
* Checks the immutablity of entities.
*
* The interceptor must be registered!!
*
* @author Thomas Kuhlmann (kuhl025), arvato D1CS, extern
*/
public class ImmutableCheckInterceptor extends EmptyInterceptor {
private static final long serialVersionUID = -298527553545916632L;
private static final Logger LOG = LoggerFactory.getLogger(ImmutableCheckInterceptor.class);
/**
* Checks the immutablity of entities.
*
* @throws IllegalModifactionException
* in case of an illegal modification.
* @see org.hibernate.EmptyInterceptor#onFlushDirty(java.lang.Object, java.io.Serializable, java.lang.Object[], java.lang.Object[], java.lang.String[], org.hibernate.type.Type[])
*/
@Override
public boolean onFlushDirty(Object entity, Serializable id, Object[] currentState, Object[] previousState, String[] propertyNames, Type[] types) {
boolean modified = false;
// Check for Immutable annoation
if (AnnotationUtils.findAnnotation(entity.getClass(), Immutable.class) != null) {
// For every property
for (int i = 0; i < propertyNames.length; i++) {
// Check for modification
if (!checkForModification(currentState[i], previousState[i])) {
// Get modified field
Field field = ReflectionUtils.findField(entity.getClass(), propertyNames[i]);
// Check if modification is allowed or illegal
if (!checkModificationAllowed(field, previousState[i])) {
// Throwing an (even runtime-) exception is not allowed here and leaves persistence in a very inconsistent state.
String msg = String.format("ILLEGAL MODIFICATION ATTEMPT: %s[%s].%s: %s -> %s", entity.getClass(), id, propertyNames[i], previousState[i], currentState[i]);
LOG.error(msg);
// Revert modification
currentState[i] = previousState[i];
modified = true;
}
}
}
}
return modified;
}
private boolean checkForModification(Object currentState, Object previousState) {
if (currentState == null && previousState == null) {
return true;
}
if (currentState instanceof Date) {
return ((Date) currentState).getTime() == ((Date) previousState).getTime();
}
return currentState != null && currentState.equals(previousState);
}
/**
* Returns true, if modification is allowed.
*/
private boolean checkModificationAllowed(Field field, Object previous) {
Mutable mutableAnnotation = findMutableAnnotation(field);
// No Mutable annotation -> Illegal modification
if (mutableAnnotation == null) {
return false;
}
// If finall, previous value must be null, otherwise it is a illegal modification
if (mutableAnnotation.finall()) {
return previous == null;
}
// Mutable annotation is present and not finall. -> Allowed modification.
return true;
}
/**
* Returns the {@link Mutable} anntotation for the {@link Field}, or null, if not found.
*/
private Mutable findMutableAnnotation(Field field) {
for (Annotation annotation : field.getDeclaredAnnotations()) {
if (annotation instanceof Mutable) {
return (Mutable) annotation;
}
}
return null;
}
}