org.eclipse.persistence.descriptors.MethodClassExtractor Maven / Gradle / Ivy
Show all versions of org.eclipse.persistence.core Show documentation
/*
* Copyright (c) 1998, 2018 Oracle and/or its affiliates. All rights reserved.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License v. 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0,
* or the Eclipse Distribution License v. 1.0 which is available at
* http://www.eclipse.org/org/documents/edl-v10.php.
*
* SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
*/
// Contributors:
// Oracle - initial API and implementation from Oracle TopLink
package org.eclipse.persistence.descriptors;
import java.lang.reflect.*;
import java.security.AccessController;
import java.security.PrivilegedActionException;
import org.eclipse.persistence.internal.helper.*;
import org.eclipse.persistence.exceptions.*;
import org.eclipse.persistence.internal.sessions.AbstractRecord;
import org.eclipse.persistence.sessions.Session;
import org.eclipse.persistence.sessions.Record;
import org.eclipse.persistence.internal.security.*;
/**
* Purpose:
* Used to allow complex inheritance support. Typically class indicators are used to define inheritance in the database,
* however in complex cases the class type may be determined through another mechanism.
* The method calls a static method on the descriptor class to determine the class to use for the database row.
*
* @see org.eclipse.persistence.descriptors.InheritancePolicy#setClassExtractor
*/
public class MethodClassExtractor extends ClassExtractor {
protected transient ClassDescriptor descriptor;
protected String classExtractionMethodName;
protected transient Method classExtractionMethod;
/**
* INTERNAL:
* Return all the classExtractionMethod
*/
public Method getClassExtractionMethod() {
return classExtractionMethod;
}
/**
* PUBLIC:
* A class extraction method can be registered with the descriptor to override the default inheritance mechanism.
* This allows for the class indicator field to not be used, and a user defined one instead.
* The method registered must be a static method on the class that the descriptor is for,
* the method must take DatabaseRow as argument, and must return the class to use for that row.
* This method will be used to decide which class to instantiate when reading from the database.
* It is the application's responsibility to populate any typing information in the database required
* to determine the class from the row.
* If this method is used then the class indicator field and mapping cannot be used,
* also the descriptor's withAllSubclasses and onlyInstances expressions must also be setup correctly.
*/
public String getClassExtractionMethodName() {
return classExtractionMethodName;
}
/**
* INTERNAL:
*/
protected void setClassExtractionMethod(Method classExtractionMethod) {
this.classExtractionMethod = classExtractionMethod;
}
/**
* PUBLIC:
* A class extraction method can be registered with the descriptor to override the default inheritance mechanism.
* This allows for the class indicator field to not be used, and a user defined one instead.
* The method registered must be a static method on the class that the descriptor is for,
* the method must take DatabaseRow as argument, and must return the class to use for that row.
* This method will be used to decide which class to instantiate when reading from the database.
* It is the application's responsibility to populate any typing information in the database required
* to determine the class from the row.
* If this method is used then the class indicator field and mapping cannot be used,
* also the descriptor's withAllSubclasses and onlyInstances expressions must also be setup correctly.
*/
public void setClassExtractionMethodName(String staticClassClassExtractionMethod) {
this.classExtractionMethodName = staticClassClassExtractionMethod;
}
/**
* INTERNAL:
* Setup the default classExtractionMethod, or if one was specified by the user make sure it is valid.
*/
public void initialize(ClassDescriptor descriptor, Session session) throws DescriptorException {
setDescriptor(descriptor);
Class[] declarationParameters = new Class[1];
declarationParameters[0] = ClassConstants.DatabaseRow_Class;
try {
setClassExtractionMethod(Helper.getDeclaredMethod(descriptor.getJavaClass(), getClassExtractionMethodName(), declarationParameters));
} catch (NoSuchMethodException ignore) {
declarationParameters[0] = ClassConstants.Record_Class;
try {
setClassExtractionMethod(Helper.getDeclaredMethod(descriptor.getJavaClass(), getClassExtractionMethodName(), declarationParameters));
} catch (NoSuchMethodException exception) {
throw DescriptorException.noSuchMethodWhileInitializingClassExtractionMethod(getClassExtractionMethodName(), descriptor, exception);
} catch (SecurityException exception) {
throw DescriptorException.securityWhileInitializingClassExtractionMethod(getClassExtractionMethodName(), descriptor, exception);
}
} catch (SecurityException exception) {
throw DescriptorException.securityWhileInitializingClassExtractionMethod(getClassExtractionMethodName(), descriptor, exception);
}
// CR#2818667 Ensure the method is static.
if (!Modifier.isStatic(getClassExtractionMethod().getModifiers())) {
throw DescriptorException.classExtractionMethodMustBeStatic(getClassExtractionMethodName(), descriptor);
}
}
/**
* INTERNAL
* Extract/compute the class from the database row and return the class.
* Map is used as the public interface to database row, the key is the field name,
* the value is the database value.
*/
public Class extractClassFromRow(Record row, org.eclipse.persistence.sessions.Session session) {
Class classForRow;
try {
Object[] arguments = new Object[1];
arguments[0] = row;
if (PrivilegedAccessHelper.shouldUsePrivilegedAccess()){
try {
classForRow = (Class)AccessController.doPrivileged(new PrivilegedMethodInvoker(getClassExtractionMethod(), null, arguments));
} catch (PrivilegedActionException exception) {
Exception throwableException = exception.getException();
if (throwableException instanceof IllegalAccessException) {
throw DescriptorException.illegalAccessWhileInvokingRowExtractionMethod((AbstractRecord)row, getClassExtractionMethod(), getDescriptor(), throwableException);
} else {
throw DescriptorException.targetInvocationWhileInvokingRowExtractionMethod((AbstractRecord)row, getClassExtractionMethod(), getDescriptor(), throwableException);
}
}
} else {
classForRow = (Class)PrivilegedAccessHelper.invokeMethod(getClassExtractionMethod(), null, arguments);
}
} catch (IllegalAccessException exception) {
throw DescriptorException.illegalAccessWhileInvokingRowExtractionMethod((AbstractRecord)row, getClassExtractionMethod(), getDescriptor(), exception);
} catch (InvocationTargetException exception) {
throw DescriptorException.targetInvocationWhileInvokingRowExtractionMethod((AbstractRecord)row, getClassExtractionMethod(), getDescriptor(), exception);
}
return classForRow;
}
/**
* INTERNAL:
* Return the descriptor.
*/
protected ClassDescriptor getDescriptor() {
return descriptor;
}
/**
* INTERNAL:
* Set the descriptor.
*/
protected void setDescriptor(ClassDescriptor descriptor) {
this.descriptor = descriptor;
}
}