我正在努力使用空指针，奇怪的是没有关系映射它起作用，但是在我添加映射（多对一，一对多）后，它无法从DB检索结果（意味着List保持为null ）
继承代码
package entityfacade.impl;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import entity.CategoryCompetenceEnumEntity;
import entity.CompetenceEntity;
import entity.impl.CompetenceEntityImpl;
import entityfacade.CategoryCompetenceEnumFacade;
import coma.entityfacade.CompetenceFacade;
import coma.objects.impl.FacadeGenerator;
import coma.objects.impl.FactoryGenerator;
public class CompetenceFacadeImpl implements CompetenceFacade {
/**
* DONE
*/
FactoryGenerator fa = new FactoryGenerator();
SessionFactory factory = fa.getFactory();
@Override
public CompetenceEntity getCompetenceEntityByName(String name) {
Transaction tx = null;
Session session = factory.openSession();
ArrayList<CompetenceEntity> entity = null;
try {
tx = session.beginTransaction();
entity = (ArrayList<CompetenceEntity>) session
.createQuery("FROM CompetenceEntityImpl C WHERE C.nameCompetence = " + name).getResultList();
tx.commit();
} catch (Exception e) {
if (tx != null)
tx.rollback();
} finally {
session.close();
}
return entity.get(0);
}
/**
* DONE
*/
@Override
public CompetenceEntity getCompetenceByIdCompetence(int id) {
Transaction tx = null;
Session session = factory.openSession();
ArrayList<CompetenceEntity> entity = null;
try {
tx = session.beginTransaction();
entity = (ArrayList<CompetenceEntity>) session
.createQuery("FROM CompetenceEntityImpl C WHERE C.idCompetence = " + id).getResultList();
tx.commit();
} catch (Exception e) {
if (tx != null)
tx.rollback();
} finally {
session.close();
}
return entity.get(0);
}
/**
* DONE
*/
@Override
public List<CompetenceEntity> getAllCompetencies() {
Transaction tx = null;
SessionFactory factory = new Configuration().configure().buildSessionFactory();
Session session = factory.openSession();
List<CompetenceEntity> competencies = null;
try {
tx = session.beginTransaction();
competencies = (List<CompetenceEntity>) session.createQuery("FROM CompetenceEntityImpl").getResultList();
tx.commit();
session.close();
} catch (Exception e) {
if (tx != null)
tx.rollback();
} finally {
factory.close();
}
if (competencies.size() < 1) {
return null;
}
// Sort the criteria semi-lexicographically as defined in class
// CompetenceComparator
competencies.sort(new CompetenceComparator());
return competencies;
}
/**
* refactored DONE
*/
@Override
public boolean deleteCompetenceById(int id) {
CompetenceEntity competence;
try {
competence = (CompetenceEntity) getCompetenceByIdCompetence(id);
} catch (Exception e) {
return false;
}
Transaction tx = null;
Session session = factory.openSession();
try {
tx = session.beginTransaction();
session.delete(competence);
tx.commit();
} catch (Exception e) {
if (tx != null)
tx.rollback();
return false;
} finally {
session.close();
}
return true;
}
/**
* refactored DONE TODO Implement MySQL filter instead of Java filter
*/
@Override
public List<CompetenceEntity> getCompetenceByFilter(String filter) {
List<CompetenceEntity> competenceEntityList = getAllCompetencies();
List<CompetenceEntity> filteredList = new ArrayList<>();
for (CompetenceEntity c : competenceEntityList) {
if (c.getNameCompetence().contains(filter)) {
filteredList.add(c);
}
}
if (filteredList.size() < 1) {
return null;
}
// Sort the criteria semi-lexicographically as defined in class
// CompetenceComparator
filteredList.sort(new CompetenceComparator());
return filteredList;
}
/**
* refactored
*
*/
@Override
public boolean insertCompetence(CompetenceEntity competenceEntity) {
// Check if competence name is not empty
if (competenceEntity.getNameCompetence().isEmpty()) {
return false;
}
// check if competence name exists
List<CompetenceEntity> competenceEntityList = getAllCompetencies();
for (CompetenceEntity ce : competenceEntityList) {
if (competenceEntity.getNameCompetence().equals(ce.getNameCompetence())) {
return false;
}
}
// check if categoryCompetenceEnum id is valid
CategoryCompetenceEnumFacade catCompFacade = FacadeGenerator.generateCategoryCompetenceEnumFacade();
List<Integer> enumIdList = new ArrayList<>();
for (CategoryCompetenceEnumEntity ce : catCompFacade.getAllCategoryCompetencies()) {
enumIdList.add(ce.getIdCategoryCompetenceEnum());
}
if (!enumIdList.contains(competenceEntity.getIdCategoryCompetenceEnum())) {
return false;
}
Transaction tx = null;
Session session = factory.openSession();
try {
tx = session.beginTransaction();
CompetenceEntity competence = new CompetenceEntityImpl();
competence.setNameCompetence(competenceEntity.getNameCompetence());
competence.setIdCategoryCompetenceEnum(competenceEntity.getIdCategoryCompetenceEnum());
session.save(competence);
tx.commit();
} catch (Exception e) {
if (tx != null)
tx.rollback();
return false;
} finally {
session.close();
}
return true;
}
}
/**
* refactored DONE
*/
class CompetenceComparator implements Comparator<CompetenceEntity> {
@Override
public int compare(CompetenceEntity c1, CompetenceEntity c2) {
// If c1 and c2 both start or both do not start with a
// letter, return lexicographic comparison
if (startsWithLetter(c1.getNameCompetence()) && startsWithLetter(c2.getNameCompetence())
|| !startsWithLetter(c1.getNameCompetence()) && !startsWithLetter(c2.getNameCompetence()))
return c1.getNameCompetence().compareTo(c2.getNameCompetence());
// If c1 does not start with a letter, but c2 does, return
// -1
if (!startsWithLetter(c1.getNameCompetence()) && startsWithLetter(c2.getNameCompetence()))
return 1;
// If c2 does not start with a letter, but c1 does, return
// 1
if (startsWithLetter(c1.getNameCompetence()) && !startsWithLetter(c2.getNameCompetence()))
return -1;
return 0;
}
/**
* refactored DONE
*/
private boolean startsWithLetter(String str) {
if (str.length() < 1)
return false;
char c = str.charAt(0);
System.out.print("String = " + str + " c = " + c);
if (c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z') {
System.out.println(" true");
return true;
}
System.out.println(" false");
return false;
}
}
实体类
package coma.entity.impl;
import java.io.Serializable;
import java.util.Set;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;
import coma.entity.CriteriaEntity;
import coma.exception.InvalidIDException;
@Entity
@Table(name = "criteria")
public class CriteriaEntityImpl implements CriteriaEntity, Serializable {
/**
*
*/
private static final long serialVersionUID = 335515262135054142L;
@OneToMany(fetch = FetchType.EAGER, mappedBy = "criteriaEntityImpl", targetEntity = CompetenceCriteriaEntityImpl.class)
public Set<CompetenceCriteriaEntityImpl> competenceCriteriaEntityImpl;
/**
*
*/
/**
* Identifier of criteria
*/
/**
*
*/
/**
* Identifier of criteria
*/
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
@Column(name = "id_criteria")
private int idCriteria;
public Set<CompetenceCriteriaEntityImpl> getCompetenceCriteriaEntityImpl() {
return competenceCriteriaEntityImpl;
}
public void setCompetenceCriteriaEntityImpl(Set<CompetenceCriteriaEntityImpl> competenceCriteriaEntityImpl) {
this.competenceCriteriaEntityImpl = competenceCriteriaEntityImpl;
}
public String getDescriptionCriteria() {
return descriptionCriteria;
}
public void setDescriptionCriteria(String descriptionCriteria) {
this.descriptionCriteria = descriptionCriteria;
}
public void setIdCriteria(int idCriteria) {
this.idCriteria = idCriteria;
}
/**
* Name of criteria
*/
@Column(name = "name_criteria")
private String nameCriteria;
/**
* Identifier type criteria
*/
@Column(name = "id_name_type_criteria_enum")
private int idNameTypeCriteriaEnum;
/**
* Description of criteria
*/
@Column(name = "description_criteria")
private String descriptionCriteria;
/**
* Constructor without parameters
*/
public CriteriaEntityImpl() {
}
/**
* Constructor with parameters
*
* @param idCriteria
* @param nameCriteria
* @param idNameTypeCriteriaEnum
* @param descriptionCriteria
*/
public CriteriaEntityImpl(int idCriteria, String nameCriteria, int idNameTypeCriteriaEnum,
String descriptionCriteria) {
this.idCriteria = idCriteria;
this.nameCriteria = nameCriteria;
this.idNameTypeCriteriaEnum = idNameTypeCriteriaEnum;
this.descriptionCriteria = descriptionCriteria;
}
/**
* Return identifier of current criteria
*
* @return idCriteria
*/
@Override
public int getIdCriteria() {
return idCriteria;
}
/**
* Return name of current criteria
*
* @return nameCriteria
*/
@Override
public String getNameCriteria() {
return nameCriteria;
}
/**
* Set name of current criteria
*
* @param nameCriteria
*/
@Override
public void setNameCriteria(String nameCriteria) {
this.nameCriteria = nameCriteria;
}
/**
* Return identifier type criteria
*
* @return idNameTypeCriteriaEnum
*/
@Override
public int getIdNameTypeCriteriaEnum() {
return idNameTypeCriteriaEnum;
}
/**
* Set identifier type criteria
*
* @param idNameTypeCriteriaEnum
*/
@Override
public void setIdNameTypeCriteriaEnum(int idNameTypeCriteriaEnum) throws InvalidIDException {
if (idNameTypeCriteriaEnum < 0) {
throw new InvalidIDException("The idNameTypeCriteriaEnum must be greater than 0");
} else {
this.idNameTypeCriteriaEnum = idNameTypeCriteriaEnum;
}
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((descriptionCriteria == null) ? 0 : descriptionCriteria.hashCode());
result = prime * result + idCriteria;
result = prime * result + idNameTypeCriteriaEnum;
result = prime * result + ((nameCriteria == null) ? 0 : nameCriteria.hashCode());
return result;
}
@Override
public boolean equals(Object obj) {
if (this == obj)
return true;
if (obj == null)
return false;
if (getClass() != obj.getClass())
return false;
CriteriaEntityImpl other = (CriteriaEntityImpl) obj;
if (descriptionCriteria == null) {
if (other.descriptionCriteria != null)
return false;
} else if (!descriptionCriteria.equals(other.descriptionCriteria))
return false;
if (idCriteria != other.idCriteria)
return false;
if (idNameTypeCriteriaEnum != other.idNameTypeCriteriaEnum)
return false;
if (nameCriteria == null) {
if (other.nameCriteria != null)
return false;
} else if (!nameCriteria.equals(other.nameCriteria))
return false;
return true;
}
}
和错误
SEVERE: Servlet.service() for servlet [Jersey RESTful Application] in context with path [/COMAService] threw exception [java.lang.NullPointerException] with root cause
java.lang.NullPointerException
at coma.entityfacade.impl.CompetenceFacadeImpl.getAllCompetencies(CompetenceFacadeImpl.java:109)
at coma.service.impl.CompetenceServiceImpl.postAll(CompetenceServiceImpl.java:86)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)