我是JavaEE的新手，我遇到了一个问题，即使用实体类和ejb的实体管理器来持久化外键指向另一个表的主键的表。我正在使用Netbeans。
我有一个名为'property'的实体，并有另一个名为'offer'的实体，它保存指向该属性主键的外键。所以基本上，逻辑是一个属性可以有很多优惠。因此，我试图使用实体管理器在“商品”表中添加新商品，但我无法做到。您可以查看代码并查看我可能缺少的内容。
物业实体：
@Entity
@Table(name = "PROPERTY")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "Property.findAll", query = "SELECT p FROM Property p")})
public class Property implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@Column(name = "PROPERTYID")
private Integer propertyid;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 500)
@Column(name = "DESCRIPTION")
private String description;
@Size(max = 50)
@Column(name = "TYPE")
private String type;
@Column(name = "NUMBEROFBEDROOM")
private Integer numberofbedroom;
@Column(name = "NUMBEROFBATHROOM")
private Integer numberofbathroom;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 10)
@Column(name = "ISFURNISHED")
private String isfurnished;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 10)
@Column(name = "HASGARDEN")
private String hasgarden;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 20)
@Column(name = "SIZE")
private String size;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 100)
@Column(name = "PRICE")
private String price;
@Basic(optional = false)
@NotNull
@Column(name = "ENTEREDDATE")
@Temporal(TemporalType.DATE)
private Date entereddate;
@Basic(optional = false)
@NotNull
@Column(name = "ENTEREDTIME")
@Temporal(TemporalType.TIME)
private Date enteredtime;
@OneToOne(cascade = CascadeType.ALL, mappedBy = "property")
private Paddress paddress;
@OneToMany(cascade = CascadeType.ALL, mappedBy = "propertyid")
private Collection<Offer> offerCollection;
@JoinColumn(name = "PROPERTYOWNERID", referencedColumnName = "PROPERTYOWNERID")
@ManyToOne(optional = false)
private Propertyowner propertyownerid;
@JoinColumn(name = "REALESTATEAGENTID", referencedColumnName = "REALESTATEAGENTID")
@ManyToOne(optional = false)
private Realestateagent realestateagentid;
public Property() {
}
public Property(Integer propertyid) {
this.propertyid = propertyid;
}
public Property(Integer propertyid, String description, String isfurnished, String hasgarden, String size, String price, Date entereddate, Date enteredtime) {
this.propertyid = propertyid;
this.description = description;
this.isfurnished = isfurnished;
this.hasgarden = hasgarden;
this.size = size;
this.price = price;
this.entereddate = entereddate;
this.enteredtime = enteredtime;
}
public Integer getPropertyid() {
return propertyid;
}
public void setPropertyid(Integer propertyid) {
this.propertyid = propertyid;
}
public String getDescription() {
return description;
}
public void setDescription(String description) {
this.description = description;
}
public String getType() {
return type;
}
public void setType(String type) {
this.type = type;
}
public Integer getNumberofbedroom() {
return numberofbedroom;
}
public void setNumberofbedroom(Integer numberofbedroom) {
this.numberofbedroom = numberofbedroom;
}
public Integer getNumberofbathroom() {
return numberofbathroom;
}
public void setNumberofbathroom(Integer numberofbathroom) {
this.numberofbathroom = numberofbathroom;
}
public String getIsfurnished() {
return isfurnished;
}
public void setIsfurnished(String isfurnished) {
this.isfurnished = isfurnished;
}
public String getHasgarden() {
return hasgarden;
}
public void setHasgarden(String hasgarden) {
this.hasgarden = hasgarden;
}
public String getSize() {
return size;
}
public void setSize(String size) {
this.size = size;
}
public String getPrice() {
return price;
}
public void setPrice(String price) {
this.price = price;
}
public Date getEntereddate() {
return entereddate;
}
public void setEntereddate(Date entereddate) {
this.entereddate = entereddate;
}
public Date getEnteredtime() {
return enteredtime;
}
public void setEnteredtime(Date enteredtime) {
this.enteredtime = enteredtime;
}
public Paddress getPaddress() {
return paddress;
}
public void setPaddress(Paddress paddress) {
this.paddress = paddress;
}
@XmlTransient
public Collection<Offer> getOfferCollection() {
return offerCollection;
}
public void setOfferCollection(Collection<Offer> offerCollection) {
this.offerCollection = offerCollection;
}
public Propertyowner getPropertyownerid() {
return propertyownerid;
}
public void setPropertyownerid(Propertyowner propertyownerid) {
this.propertyownerid = propertyownerid;
}
public Realestateagent getRealestateagentid() {
return realestateagentid;
}
public void setRealestateagentid(Realestateagent realestateagentid) {
this.realestateagentid = realestateagentid;
}
public String dateToString()
{
DateFormat df = new SimpleDateFormat("dd/MM/yy");
return df.format(entereddate);
}
public String timeToString()
{
DateFormat df = new SimpleDateFormat("HH:mm:ss");
return df.format(enteredtime);
}
@Override
public int hashCode() {
int hash = 0;
hash += (propertyid != null ? propertyid.hashCode() : 0);
return hash;
}
@Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof Property)) {
return false;
}
Property other = (Property) object;
if ((this.propertyid == null && other.propertyid != null) || (this.propertyid != null && !this.propertyid.equals(other.propertyid))) {
return false;
}
return true;
}
@Override
public String toString() {
return "com.sushan.model.Property[ propertyid=" + propertyid + " ]";
}
}
EJB PropertyDAO：
@Stateless
public class PropertyDAO implements PropertyDAOLocal {
@PersistenceContext(unitName="RealEstateWebsite-ejbPU")
private EntityManager em;
@Override
public void AddProperty(Property property) {
em.persist(property);
}
@Override
public void EditProperty(Property property) {
em.merge(property);
}
@Override
public void DeleteProperty(int propertyId) {
em.remove(GetProperty(propertyId));
}
@Override
public List<Property> GetAllProperty() {
return em.createNamedQuery("Property.findAll").getResultList();
}
@Override
public Property GetProperty(int propertyId) {
return em.find(Property.class, propertyId);
}
@Override
public void EditPropertyAddress(Paddress propertyAddress) {
em.merge(propertyAddress);
}
}
提供实体：
@Entity
@Table(name = "OFFER")
@XmlRootElement
@NamedQueries({
@NamedQuery(name = "Offer.findAll", query = "SELECT o FROM Offer o")})
public class Offer implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Basic(optional = false)
@Column(name = "OFFERID")
private Integer offerid;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 100)
@Column(name = "OFFERSTATUS")
private String offerstatus;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 100)
@Column(name = "ORIGINALOFFER")
private String originaloffer;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 100)
@Column(name = "OFFERINGBP")
private String offeringbp;
@Basic(optional = false)
@NotNull
@Column(name = "OFFEREDDATE")
@Temporal(TemporalType.DATE)
private Date offereddate;
@Basic(optional = false)
@NotNull
@Column(name = "OFFEREDTIME")
@Temporal(TemporalType.TIME)
private Date offeredtime;
@JoinColumn(name = "BUYERID", referencedColumnName = "BUYERID")
@ManyToOne(optional = false)
private Buyer buyerid;
@JoinColumn(name = "PROPERTYID", referencedColumnName = "PROPERTYID")
@ManyToOne(optional = false)
private Property propertyid;
public Offer() {
}
public Offer(Integer offerid) {
this.offerid = offerid;
}
public Offer(String offerstatus, String originaloffer, String offeringbp, Date offereddate, Date offeredtime, Buyer buyerid, Property propertyid) {
this.offerstatus = offerstatus;
this.originaloffer = originaloffer;
this.offeringbp = offeringbp;
this.offereddate = offereddate;
this.offeredtime = offeredtime;
this.buyerid = buyerid;
this.propertyid = propertyid;
}
public Integer getOfferid() {
return offerid;
}
public void setOfferid(Integer offerid) {
this.offerid = offerid;
}
public String getOfferstatus() {
return offerstatus;
}
public void setOfferstatus(String offerstatus) {
this.offerstatus = offerstatus;
}
public String getOriginaloffer() {
return originaloffer;
}
public void setOriginaloffer(String originaloffer) {
this.originaloffer = originaloffer;
}
public String getOfferingbp() {
return offeringbp;
}
public void setOfferingbp(String offeringbp) {
this.offeringbp = offeringbp;
}
public Date getOffereddate() {
return offereddate;
}
public void setOffereddate(Date offereddate) {
this.offereddate = offereddate;
}
public Date getOfferedtime() {
return offeredtime;
}
public void setOfferedtime(Date offeredtime) {
this.offeredtime = offeredtime;
}
public Buyer getBuyerid() {
return buyerid;
}
public void setBuyerid(Buyer buyerid) {
this.buyerid = buyerid;
}
public Property getPropertyid() {
return propertyid;
}
public void setPropertyid(Property propertyid) {
this.propertyid = propertyid;
}
@Override
public int hashCode() {
int hash = 0;
hash += (offerid != null ? offerid.hashCode() : 0);
return hash;
}
@Override
public boolean equals(Object object) {
// TODO: Warning - this method won't work in the case the id fields are not set
if (!(object instanceof Offer)) {
return false;
}
Offer other = (Offer) object;
if ((this.offerid == null && other.offerid != null) || (this.offerid != null && !this.offerid.equals(other.offerid))) {
return false;
}
return true;
}
@Override
public String toString() {
return "com.sushan.model.Offer[ offerid=" + offerid + " ]";
}
EJB OfferDAO：
@Stateless
public class OfferDAO implements OfferDAOLocal {
@PersistenceContext(unitName="RealEstateWebsite-ejbPU")
EntityManager em;
@Override
public void EditOffer(Offer offer) {
em.merge(offer);
}
@Override
public List<Offer> GetAllOffer(int propertyId) {
return em.createNamedQuery("Offer.findByPropertyID").setParameter("propertyID", propertyId).getResultList();
}
@Override
public List<Offer> GetAllOffer() {
return em.createNamedQuery("Offer.findAll").getResultList();
}
@Override
public void Add(Offer offer) {
em.persist(offer);
}
}
将JSP与EJB连接的Servlet：
String action = request.getParameter("action");
String currencyType = request.getParameter("ddlCurrencyType");
String amount = request.getParameter("offerAmount");
String propertyIdStr = request.getParameter("hdnbt");
if ("Offer".equalsIgnoreCase(action))
{
if ("".equals(action) & !"".equals(currencyType) & !"".equals(amount) & !"".equals(propertyIdStr))
{
DateFormat df = new SimpleDateFormat("dd/MM/yy");
DateFormat df1 = new SimpleDateFormat("HH:mm:ss");
Date currentDate = new Date();
Date currentTime = new Date();
int propertyId = Integer.parseInt(propertyIdStr);
try {
currentDate = df.parse(df.format(currentDate));
currentTime = df1.parse(df1.format(currentTime));
} catch (ParseException e) {
}
Buyer buyer = buyerDAO.GetBuyer(1);
Property property = propertyDAO.GetProperty(propertyId);
Offer offer = new Offer("Pending", amount, amount, currentDate, currentTime, buyer, property);
offerDAO.Add(offer);
}
else
{
}
}
request.setAttribute("allProperty", propertyDAO.GetAllProperty());
request.getRequestDispatcher("AdministerProperty.jsp").forward(request, response);
我在这里遗漏了什么吗？我已经按照一个没有外键指导的教程，但试图用我自己的逻辑绕过它，但它没有用。我找不到使用类似于我的方法的可靠来源。我找到的大部分资源都是针对Hibernate的，但我使用的是EJB。
答案 0 :(得分：0)
检索属性的方法和保留Offer的方法似乎在单独的事务中运行（DAO是无状态会话bean）。
这意味着将使用分离的属性填充和保留商品，因此持久性提供商不会意识到它。
不确定为什么不引发异常，但您必须首先合并Property，或者在保留Offer的同一事务中执行查询：
@Override
public void Add(Offer offer, int peropertyId) {
Property property = em.find(Property.class, propertyId);
offer.setPeropertyId(property);
em.persist(offer);
}
或
@Override
public void Add(Offer offer, Property peroperty) {
Property managedProperty = em.merge(property);
offer.setPeropertyId(managedProperty);
em.persist(offer);
}
答案 1 :(得分：0)
我修好了。如果你看一下servlet的代码，我if条件的问题是检查action参数。这意味着如果动作不是空的，但它会检查动作是否为空。我通过创建一个整数来找到这个问题，当它到达代码中的某些阶段时会自行递增。
我认为你必须在同一笔交易中获取属性ID和买方ID是正确的。否则那对我来说就是下一个问题。谢谢。