org.activiti.engine.impl.variable.JPAEntityScanner Maven / Gradle / Ivy
/* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.activiti.engine.impl.variable;
import org.activiti.engine.ActivitiException;
import javax.persistence.Entity;
import javax.persistence.Id;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
/**
* Scans class and creates {@link EntityMetaData} based on it.
*
*/
public class JPAEntityScanner {
public EntityMetaData scanClass(Class clazz) {
EntityMetaData metaData = new EntityMetaData();
// in case with JPA Enhancement
// method should iterate over superclasses list
// to find @Entity and @Id annotations
while (clazz != null && !clazz.equals(Object.class)) {
// Class should have @Entity annotation
boolean isEntity = isEntityAnnotationPresent(clazz);
if (isEntity) {
metaData.setEntityClass(clazz);
metaData.setJPAEntity(true);
// Try to find a field annotated with @Id
Field idField = getIdField(clazz);
if (idField != null) {
metaData.setIdField(idField);
} else {
// Try to find a method annotated with @Id
Method idMethod = getIdMethod(clazz);
if (idMethod != null) {
metaData.setIdMethod(idMethod);
} else {
throw new ActivitiException("Cannot find field or method with annotation @Id on class '" + clazz.getName() + "', only single-valued primary keys are supported on JPA-entities");
}
}
break;
}
clazz = clazz.getSuperclass();
}
return metaData;
}
private Method getIdMethod(Class clazz) {
Method idMethod = null;
// Get all public declared methods on the class. According to spec, @Id
// should only be
// applied to fields and property get methods
Method[] methods = clazz.getMethods();
Id idAnnotation = null;
for (Method method : methods) {
idAnnotation = method.getAnnotation(Id.class);
if(idAnnotation != null && !method.isBridge()) {
idMethod = method;
break;
}
}
return idMethod;
}
private Field getIdField(Class clazz) {
Field idField = null;
Field[] fields = clazz.getDeclaredFields();
Id idAnnotation = null;
for (Field field : fields) {
idAnnotation = field.getAnnotation(Id.class);
if (idAnnotation != null) {
idField = field;
break;
}
}
if (idField == null) {
// Check superClass for fields with @Id, since getDeclaredFields
// does
// not return superclass-fields.
Class superClass = clazz.getSuperclass();
if (superClass != null && !superClass.equals(Object.class)) {
// Recursively go up class hierarchy
idField = getIdField(superClass);
}
}
return idField;
}
private boolean isEntityAnnotationPresent(Class clazz) {
return (clazz.getAnnotation(Entity.class) != null);
}
}