我正在玩交易。
我配置了 JPA 来处理我的实体，并希望将它们保存在数据库中。问题是，当我的程序抛出runtimeException时，CMT不会回滚。
这个“容器事物”背后的想法很难理解，而且记录也很少。
@transactional 托管事务、纯 CDI 拦截器托管事务和 Bean 托管事务运行得非常顺利。
这是我编码的内容：这是一个简单的“电影演示”。你想看两部有 X 个座位的电影。座位有限。如果电影中没有足够的座位，则不应进行交易（ACID 等）
在我的 buyTicketsBoundary 类中：
首先我告诉全班同学我们正在使用 CMT：
@Named("buchungBoundry")
@RequestScoped
@TransactionManagement(TransactionManagementType.CONTAINER)
public class BuchungBoundry {
@EJB
private BuchungVerwaltung buyTicketsController;
@EJB
private KundenVerwaltung customerController;
@EJB
private SaalVerwaltung roomController;
@EJB
private MovieVerwaltung movieController;
private int ticketsForMovie1; //this is how many tickets we want to buy
private int ticketsForMovie2;
public BuchungBoundry() {
}
@TransactionAttribute(TransactionAttributeType.REQUIRED)
public void buyTickets() throws MyException {
int numberOfSeantsInRoom1=roomController.getSaal(4).getAnzahlPlaetze();
int numberOfSeantsInRoom2=roomController.getSaal(5).getAnzahlPlaetze();
int alreadyBoughtSeatsIn1=buyTicketsController.getBelegtePlatzeNachSaal(4);
int alreadyBoughtSeatsIn2=buyTicketsController.getBelegtePlatzeNachSaal(5);
int availableSeats1 = numberOfSeantsInRoom1 - alreadyBoughtSeatsIn1;
int availableSeats2 = numberOfSeantsInRoom2 - alreadyBoughtSeatsIn2;
System.out.println("Saal A: ("+alreadyBoughtSeatsIn1+"/"+numberOfSeantsInRoom1+") want to buy :" + ticketsForMovie1);
System.out.println("Saal B: ("+alreadyBoughtSeatsIn2+"/"+numberOfSeantsInRoom2+") want to buy :" + ticketsForMovie2);
try {
if (ticketsForMovie1 <= availableSeats1) {
buyTicketsController.erstelleBuchung(customerController.getKunde(1),
movieController.getMovie(7),
roomController.getSaal(4),
ticketsForMovie1);
} else {
throw new MyException("ERROR: no room for "
+ ticketsForMovie1 + " person! "
+alreadyBoughtSeatsIn1);
}
if (ticketsForMovie2 <= availableSeats2) {
buyTicketsController.erstelleBuchung(customerController.getKunde(1),
movieController.getMovie(8),
roomController.getSaal(5),
ticketsForMovie2);
} else {
throw new MyException("ERROR: no room for "
+ ticketsForMovie2 + " person! "
+alreadyBoughtSeatsIn2);
}
} catch (MyException | IllegalStateException | SecurityException ex) {
Logger.getLogger(BuchungBoundry.class.getName()).log(Level.SEVERE, null, ex);
}
}
我的例外：
@ApplicationException(rollback=true)
public class MyException extends RuntimeException{
public MyException() {
}
public MyException(String s) {
System.out.println(""+s);
}
}
通过 JPA 在数据库中写入已购买门票的控制器类：
@Stateless
public class BuchungVerwaltung implements Serializable {
@PersistenceContext(unitName = "kbse-JTA")
private EntityManager em;
public BuchungVerwaltung() {
}
public void erstelleBuchung(Kunde k, Movie movie, Saal saal, int anzahlPlaetze) {
Buchung b = new Buchung(k, movie, saal, anzahlPlaetze);
em.persist(b);
}
public int getBelegtePlatzeNachSaal(int id) {
try {
Query query = em.createNativeQuery("select sum(b.ANZAHL) from SAAL s,BUCHUNG b where s.SAAL_ID = b.SAAL_SAAL_ID and s.SAAL_ID=?");
query.setParameter(1, id);
return (int) query.getSingleResult();
} catch (Exception e) {
return 0;
}
}
public List<Buchung> getAlleBuchungen() {
TypedQuery<Buchung> query = em.createQuery("select s from Buchung s", Buchung.class);
return query.getResultList();
}
}
问题是，当此类达到第一部电影的 em.persist 状态，而第二部电影抛出异常时，数据库无法回滚。
我认为如果抛出 RuntimeException，容器就会回滚
我可以做什么来让它发挥作用？
如果有不清楚的地方请告诉我
