远程访问Jpa实体

Question

我目前正在使用由Java Web应用程序和C＃客户端应用程序组成的系统。 Web应用程序具有Java Web Service，该Java Web Service具有返回Program类的实体对象的方法：

@WebMethod(operationName = "getProgram")
public Program getProgram(@WebParam(name = "macAddress") String macAddress){
    Device device = DeviceManager.getInstance().getDevice(macAddress);
    if(device != null){
        return device.getProgram();
    }
    return null;
}

此类型为Program的返回对象，具有许多属性和关系：

@Entity
@Table(name = "PROGRAM", schema = "APP")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "Program.getProgramsByWeather", query = "SELECT p FROM Program p WHERE p.weather = :weather")})
public class Program extends DbEntity implements Serializable {

    private static final long serialVersionUID = 1L;
    @JoinColumn(name = "LOGO_ID", referencedColumnName = "ID")
    @OneToOne(cascade = CascadeType.ALL, orphanRemoval = true, fetch= FetchType.EAGER)
    private Logo logo;
    @JoinColumn(name = "WEATHER_ID", referencedColumnName = "ID")
    @ManyToOne
    private Weather weather;
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "program", orphanRemoval = true)
    private List<ProgramPlaylist> programPlaylistList = new ArrayList<>();
    @OneToMany(cascade = CascadeType.ALL, mappedBy = "program", orphanRemoval = true)
    private List<ProgramTicker> programTickerList = new ArrayList<>();
    @Column(name = "UPDATED")
    private boolean updated;

    public Program() {
    }

    public Program(String name, AppUser owner) {
        super(name, owner);
    }

    public Logo getLogo() {
        return logo;
    }

    public void setLogo(Logo logo) {
        this.logo = logo;
    }

    public Weather getWeather() {
        return weather;
    }

    public void setWeather(Weather weather) {
        this.weather = weather;
    }

    public boolean isUpdated() {
        return updated;
    }

    public void setUpdated(boolean updated) {
        this.updated = updated;
    }

    @XmlElement
    public List<ProgramPlaylist> getProgramPlaylistList() {
        return programPlaylistList;
    }

    @XmlElement
    public List<ProgramTicker> getProgramTickerList() {
        return programTickerList;
    }

    @Override
    public String toString() {
        return "Program[ id=" + getId() + " ]";
    }
}

客户端可以获取此对象并访问客户端应用程序中的某些属性，例如program.name，它是从DbEntity继承的，但是当我尝试调用类似的内容时：

program.logo.name

客户端抛出NullReferenceException。 当我尝试遍历programPlaylistList ArrayList的元素时，会发生相同的异常。

我假设传递给客户端的对象本身未完全加载。

我该如何解决此问题，请帮忙？！

编辑好，所以我打印出客户端从服务获得的XML响应，并正确填充了该响应，但是由于某些原因，没有填充对象字段，并且大多数情况下为null。 为什么会这样呢？

Answer 1

默认情况下，@OneToMany批注的获取策略为LAZY ，是否尝试过像@oneToOne字段中那样将其指定给EAGER（fetch = FetchType.EAGER）？