我正在开发 Web 项目 EJB，JPA - Hibernate 作为提供者，JBoss 6，MySql。我是 EJB、JPA 的新手。我在 servlet 中加载 ejb bean 时遇到问题。
持久性.xml
<persistence-unit name="LibraryPersistenceUnit" transaction-type="JTA">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<jta-data-source>java:/MySqlDS</jta-data-source>
<class>library.entity.User</class>
<class>library.entity.Book</class>
<properties>
<property name="hibernate.show_sql" value="true" />
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect"/>
</properties>
</persistence-unit>
UserFacade.java
@Local
public interface UserFacade {
User findUserByLoginAndPassword(String login, String password);
/* List<User> getClients();
void returnBooks(long userId, long[] ids);
void takeBooks(long userId, long[] ids);*/
}
UserFacadeImpl.java
package library.facades.impl;
import library.dao.impl.UserDAO;
import library.entity.User;
import library.facades.interfaces.UserFacade;
import javax.ejb.EJB;
import javax.ejb.Stateless;
@Stateless
public class UserFacadeImpl implements UserFacade {
@EJB
private UserDAO userDAO;
public UserFacadeImpl() {
}
public User findUserByLoginAndPassword(String login, String password) {
User user = userDAO.selectUserByLoginAndPassword(login, password);
return user;
}
/* public List<User> getListClients() {
List<User> userList = userDAO.getClients();
return userList;
}
public void returnBooks(long userId, long[] ids) {
userDAO.returnBooks(userId, ids);
}
public void takeBooks(long userId, long[] ids) {
userDAO.takeBooks(userId, ids);
}*/
}
用户DAO.java
package library.dao.impl;
import library.dao.interfaces.GenericDAO;
import library.entity.User;
import javax.ejb.Local;
import javax.ejb.Stateless;
import java.util.HashMap;
import java.util.Map;
@Stateless
public class UserDAO extends GenericDAO {
public UserDAO() {
super(User.class);
}
public User selectUserByLoginAndPassword(String login, String password) {
Map<String, Object> parameters = new HashMap<String, Object>();
parameters.put("login", login);
parameters.put("password", password);
return (User) super.findOneResult(User.SELECT_USER_BY_LOGIN_AND_PASSWORD, parameters);
}
/*public List<User> getClients() {
Query namedQuery = entityManager.createNamedQuery(User.ALL_CLIENTS, User.class);
List<User> clientsList = namedQuery.getResultList();
return clientsList;
}
@Override
public void returnBooks(long userId, long[] ids) {
User user = entityManager.find(User.class, userId);
for (long id : ids) {
Book book = entityManager.find(Book.class, id);
user.getTakenBooks().remove(book);
}
entityManager.merge(user);
}
@Override
public void takeBooks(long userId, long[] ids) {
User user = entityManager.find(User.class, userId);
for (long id : ids) {
Book book = entityManager.find(Book.class, id);
user.getTakenBooks().add(book);
}
entityManager.merge(user);
}*/
}
GenericDAO.java 包 library.dao.interfaces;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Query;
import java.util.List;
import java.util.Map;
public abstract class GenericDAO<T> {
private static final String LIBRARY_PERSISTENCE_UNIT = "LibraryPersistenceUnit";
@PersistenceContext(unitName = LIBRARY_PERSISTENCE_UNIT)
private EntityManager entityManager;
private Class<T> entityClass;
public GenericDAO() {
}
public GenericDAO(Class<T> entityClass) {
this.entityClass = entityClass;
}
public void save(T entity) {
entityManager.persist(entity);
}
protected void delete(Object id, Class<T> classe) {
T entityToBeRemoved = entityManager.getReference(classe, id);
entityManager.remove(entityToBeRemoved);
}
public T update(T entity) {
return entityManager.merge(entity);
}
public T find(int entityID) {
return entityManager.find(entityClass, entityID);
}
// Using the unchecked because JPA does not have a
// entityManager.getCriteriaBuilder().createQuery()<T> method
@SuppressWarnings({"unchecked", "rawtypes"})
public List<T> findAll() {
/* CriteriaQuery cq = entityManager.getCriteriaBuilder().createQuery();
cq.select(cq.from(entityClass));*/
return null;//entityManager.createQuery(cq).getResultList();
}
// Using the unchecked because JPA does not have a
// ery.getSingleResult()<T> method
@SuppressWarnings("unchecked")
protected T findOneResult(String namedQuery, Map<String, Object> parameters) {
T result = null;
try {
Query query = entityManager.createNamedQuery(namedQuery);
// Method that will populate parameters if they are passed not null and empty
if (parameters != null && !parameters.isEmpty()) {
populateQueryParameters(query, parameters);
}
result = (T) query.getSingleResult();
} catch (Exception e) {
System.out.println("Error while running query: " + e.getMessage());
e.printStackTrace();
}
return result;
}
private void populateQueryParameters(Query query, Map<String, Object> parameters) {
for (Map.Entry<String, Object> entry : parameters.entrySet()) {
query.setParameter(entry.getKey(), entry.getValue());
}
}
public EntityManager getEntityManager() {
return entityManager;
}
public void setEntityManager(EntityManager entityManager) {
this.entityManager = entityManager;
}
}
图书馆控制器
package library.controller;
import library.entity.User;
import library.facades.interfaces.UserFacade;
import library.resourses.constants.Constants;
import library.resourses.enums.Role;
import javax.ejb.EJB;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class LibraryController extends HttpServlet {
@EJB
private UserFacade userFacade;
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws javax.servlet.ServletException, IOException {
performAction(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws javax.servlet.ServletException, IOException {
performAction(request, response);
}
private void performAction(HttpServletRequest request, HttpServletResponse response) {
String pageType = request.getParameter(Constants.PAGE_TYPE);
if (pageType != null) {
try {
String page = null;
String login = request.getParameter(Constants.USER_LOGIN);
String password = request.getParameter(Constants.USER_PASSWORD);
User user = userFacade.findUserByLoginAndPassword(login, password);
if (user == null) {
request.getSession().setAttribute(Constants.ERROR,
Constants.ERROR_MESSAGE_7);
page = Constants.MAIN_PAGE;
} else {
String namePage = user.getRole().toString().toLowerCase();
if (isClient(user)) {
request.getSession().setAttribute(Constants.CLIENT,
user);
request.getSession().setAttribute(Constants.ERROR, null);
} else if (isAdministrator(user)) {
request.getSession().setAttribute(Constants.ADMINISTRATOR,
user);
request.getSession().setAttribute(Constants.ERROR, null);
}
page = Constants.START_PAGES + namePage + Constants.END_PAGES;
}
RequestDispatcher requestDispatcher = getServletContext().getRequestDispatcher(page);
requestDispatcher.forward(request, response);
} catch (ServletException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}
private boolean isAdministrator(User user) {
return user.getRole().equals(Role.ADMINISTRATOR);
}
private boolean isClient(User user) {
return user.getRole().equals(Role.CLIENT);
}
}
我的 userFacade 为空。你能解释一下我做错了什么吗？谢谢。