java - (JAVA EE)方法无法正常工作，不会引发任何错误

Question

我正在使用 Java EE、EJB 和 JPA (EclipseLink) 开发航空公司管理 Web 应用程序

当我从 servlet 调用服务层中的方法时遇到了麻烦:该方法没有执行预期的操作而没有任何错误。

方法是 AddPassengerToFlight，我试图将乘客添加到航类实体中具有多对多关系的乘客列表中。

这是项目的结构。

这是没有 getter 和 setter 的 Flight 和 The Passenger 实体:

航类:

public class Flight implements Serializable {


    @Id
    @GeneratedValue( strategy = GenerationType.AUTO )
    private Integer         id;

    @Enumerated( EnumType.STRING )
    private Cities          depart;

    @Enumerated( EnumType.STRING )
    private Cities          destination;

    private String          prix;

    @Temporal( TemporalType.TIMESTAMP )
    private Date            date;

    @ManyToMany( cascade = { CascadeType.MERGE, CascadeType.PERSIST, CascadeType.REFRESH } )
    @JoinTable( name = "f_p_join", joinColumns = @JoinColumn( name = "flight_fk" ), inverseJoinColumns = @JoinColumn( name = "passenger_fk" ) )
    private List<Passenger> passengers;

    @OneToOne( )
    @JoinColumn( name = "airplane_fk" )
    private Plane           airplane;

    @OneToOne( )
    @JoinColumn( name = "pilot_fk" )
    private Pilot           pilot;
}

乘客:

public class Passenger implements Serializable {


    @Id
    @GeneratedValue( strategy = GenerationType.AUTO )
    private Integer      id;

    private String       nom;

    private String       prenom;

    private String       adresse;

    private String       telephone;

    private String       email;

    @Enumerated( EnumType.STRING )
    private FlightClass  flightClass;

    @ManyToMany( mappedBy = "passengers" )
    private List<Flight> flights;
}

我有方法的 PassenerService :

public class PassengerService {

    private static final String CHAMP_FLIGHT_ID    = "flightId";
    private static final String CHAMP_PASSENGER_ID = "passengerId";

    private String              resultat;
    private Map<String, String> erreurs            = new HashMap<String, String>();
    private PassengerDao        passengerDao;
    private FlightDao           flightDao;
    private PilotDao            pilotDao;
    private PlaneDao            planeDao;

    public Map<String, String> getErreurs() {
        return erreurs;
    }

    public String getResultat() {
        return resultat;
    }

    public PassengerService( PassengerDao passengerDao, FlightDao flightDao, PilotDao pilotDao, PlaneDao planeDao ) {
        this.passengerDao = passengerDao;
        this.flightDao = flightDao;
        this.pilotDao = pilotDao;
        this.planeDao = planeDao;
    }

    public Passenger createPassenger( HttpServletRequest request ) {
        //The createPassenger code
    }

    public List<Passenger> getAllPassengers() {
        //The getAllPassengers Code
    }

    public void AddPassengerToFlight( HttpServletRequest request ) {
        FlightService flightService = new FlightService( flightDao, planeDao, pilotDao );

        String passengerId = request.getParameter( CHAMP_PASSENGER_ID );
        String flightId = request.getParameter( CHAMP_FLIGHT_ID );

        Passenger passenger = getPassengerById( passengerId );
        Flight flight = flightService.getFlightById( flightId );

        List<Passenger> pList = flight.getPassengers();
        pList.add( passenger );
        flight.setPassengers( pList );

        passenger.getFlights().add( flight );

    }

    public Passenger getPassengerById( String passengerId ) {
        Passenger passenger = passengerDao.getPassengerById( passengerId );
        return passenger;
    }

    public void removePassenger( Passenger passenger ) {
       //The removePassenger code

    }


}

这是 servlet AddPassengerToFlight

@WebServlet( "/AddPassengerToFlight" )
public class AddPassengerToFlight extends HttpServlet {

    private static final String VUE_REDIRECT     = "/airline/PassengerList";

    private static final long   serialVersionUID = 1L;

    @EJB
    FlightDao                   flightDao;

    @EJB
    PilotDao                    pilotDao;

    @EJB
    PlaneDao                    planeDao;

    @EJB
    PassengerDao                passengerDao;


    protected void doGet( HttpServletRequest request, HttpServletResponse response ) throws ServletException,
            IOException {
        FlightService flightService = new FlightService( flightDao, planeDao, pilotDao );
        PassengerService passengerService = new PassengerService( passengerDao, flightDao, pilotDao, planeDao );

        List<Flight> flights = flightService.getAllFlights();
        List<Passenger> passengers = passengerService.getAllPassengers();
        request.setAttribute( "flights", flights );
        request.setAttribute( "passengers", passengers );
        this.getServletContext().getRequestDispatcher( VUE ).forward( request, response );
    }


    protected void doPost( HttpServletRequest request, HttpServletResponse response ) throws ServletException,
            IOException {
        PassengerService passengerService = new PassengerService( passengerDao, flightDao, pilotDao, planeDao );

        passengerService.AddPassengerToFlight( request );
        response.sendRedirect( VUE_REDIRECT );

    }

}

这是 AddPassengerToFlight 表单(JSP 文件)

<div class="container">
        <h2>Adding Passenger To Flight</h2>
        <br/><br/>
        <form method="POST" action="AddPassengerToFlight">
            <div class="form-group">
                <h4>Flight :</h4>
                <select name="flightId" class="selectpicker" data-live-search="true" data-width="100%">
                    <c:forEach items="${flights}" var="flight">
                        <option value="${flight.id}">
                            FROM <c:out value="${flight.depart}" /> TO <c:out value="${flight.destination}" /> AT <c:out value="${flight.date}" />
                        </option>
                    </c:forEach>
                </select>
            </div>


            <div class="form-group">
                <h4>Passenger :</h4>
                <select name="passengerId" class="selectpicker" data-live-search="true" data-width="100%">
                    <c:forEach items="${passengers}" var="passenger">
                        <option value="${passenger.id}"><c:out value="${passenger.nom}" /></option>
                    </c:forEach>
                </select>
            </div>

            <button type="submit" class="btn btn-default">Submit</button>

        </form>
    </div>

当我单击 AddPassengerToFlight 的按钮提交时，我被重定向到 PassengerList 但两个实体(航类和乘客)之间没有任何反应，并且我没有错误。

有人能弄清楚我在这里做错了什么吗？

Answer 1

我相信你的问题是你的 PassengerService 类是一个普通的 JAVA 类(我解释一下，不是 EJB 服务)...因此，当你在该类中建立 Passanger 和 Flight 之间的关联时，没有 JTA事务正在运行并且您的实体处于分离模式；因此，对它们的任何更改都不会保留在数据库中。

您可以快速尝试一下，看看我是否正确...使您的服务成为一个 EJB 类，并通过 @EJB 注释注入(inject)所需的 DAO，从 Servlet 注入(inject)您的新 EJB，然后调用方法:AddPassengerToFlight( HttpServletRequest request ) ...