java - 使用 JPA 时，数据库中会添加 2 个条目，而不是仅 1 个

Question

在服务类中，我从一个表单提交中将数据添加到 2 个表中，它可以很好地将数据添加到 Breweries 表中，但是当数据转到 Brewerie_Geocodes 表中时，它会复制该行。我认为我的代码非常合乎逻辑，但我一定忘记了一些东西。

服务类中的方法是

public void addAnBreweries(Breweries brewerie) {
    EntityManager em = DBUtil.getEMF().createEntityManager();
    EntityTransaction trans = em.getTransaction();
    Date date = new Date();
    brewerie.setLastMod(date);
    try {
        trans.begin();
        em.persist(brewerie);
        trans.commit();

        BreweriesGeocode bg = new BreweriesGeocode();
        bg.setBreweryId((Integer) brewerie.getId());
        bg.setLongitude((float)brewerie.getLongitude());
        bg.setLatitude((float)brewerie.getLatitude());
         trans.begin();
        em.persist(bg);
        trans.commit();

    } catch (Exception ex) {
        System.out.println(ex);
    } finally {
        em.close();
    }
}

我在表中得到的数据是

啤酒厂的代码是

@实体

 @Table(name = "breweries")
    @SecondaryTable(name = "breweries_geocode")

    @XmlRootElement
    @NamedQueries({
        @NamedQuery(name = "Breweries.findAll", query = "SELECT b FROM Breweries b"),
        @NamedQuery(name = "Breweries.findById", query = "SELECT b FROM Breweries b WHERE b.id = :id"),
        @NamedQuery(name = "Breweries.findByName", query = "SELECT b FROM Breweries b WHERE b.name = :name"),
        @NamedQuery(name = "Breweries.findByAddress1", query = "SELECT b FROM Breweries b WHERE b.address1 = :address1"),
        @NamedQuery(name = "Breweries.findByAddress2", query = "SELECT b FROM Breweries b WHERE b.address2 = :address2"),
        @NamedQuery(name = "Breweries.findByCity", query = "SELECT b FROM Breweries b WHERE b.city = :city"),
        @NamedQuery(name = "Breweries.findByState", query = "SELECT b FROM Breweries b WHERE b.state = :state"),
        @NamedQuery(name = "Breweries.findByCode", query = "SELECT b FROM Breweries b WHERE b.code = :code"),
        @NamedQuery(name = "Breweries.findByCountry", query = "SELECT b FROM Breweries b WHERE b.country = :country"),
        @NamedQuery(name = "Breweries.findByPhone", query = "SELECT b FROM Breweries b WHERE b.phone = :phone"),
        @NamedQuery(name = "Breweries.findByWebsite", query = "SELECT b FROM Breweries b WHERE b.website = :website"),
        @NamedQuery(name = "Breweries.findByImage", query = "SELECT b FROM Breweries b WHERE b.image = :image"),
        @NamedQuery(name = "Breweries.findByAddUser", query = "SELECT b FROM Breweries b WHERE b.addUser = :addUser"),
        @NamedQuery(name = "Breweries.findByLastMod", query = "SELECT b FROM Breweries b WHERE b.lastMod = :lastMod"),
        @NamedQuery(name = "Breweries.findByCreditLimit", query = "SELECT b FROM Breweries b WHERE b.creditLimit = :creditLimit"),
        @NamedQuery(name = "Breweries.findByEmail", query = "SELECT b FROM Breweries b WHERE b.email = :email")})
    public class Breweries implements Serializable {

        private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id")
private Integer id;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 255)
@Column(name = "name")
private String name;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 255)
@Column(name = "address1")
private String address1;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 255)
@Column(name = "address2")
private String address2;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 255)
@Column(name = "city")
private String city;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 255)
@Column(name = "state")
private String state;
@Basic(optional = false)
@NotNull
@Size(min = 1, max = 25)
@Column(name = "code")
private String code;
@Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 255)
    @Column(name = "country")
    private String country;
    // @Pattern(regexp="^\\(?(\\d{3})\\)?[- ]?(\\d{3})[- ]?(\\d{4})$", message="Invalid phone/fax format, should be as xxx-xxx-xxxx")//if the field contains phone or fax number consider using this annotation to enforce field validation
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 50)
    @Column(name = "phone")
    private String phone;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 255)
    @Column(name = "website")
    private String website;
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 255)
    @Column(name = "image")
    private String image;
    @Basic(optional = false)
    @NotNull
    @Lob
    @Size(min = 1, max = 65535)
    @Column(name = "description")
    private String description;
    @Basic(optional = false)
    @NotNull
    @Column(name = "add_user")
    private int addUser;
    @Basic(optional = false)
    @NotNull
    @Column(name = "last_mod")
    @Temporal(TemporalType.TIMESTAMP)
    private Date lastMod;
    @Basic(optional = false)
    @NotNull
    @Column(name = "credit_limit")
    private double creditLimit;
    // @Pattern(regexp="[a-z0-9!#$%&'*+/=?^_`{|}~-]+(?:\\.[a-z0-9!#$%&'*+/=?^_`{|}~-]+)*@(?:[a-z0-9](?:[a-z0-9-]*[a-z0-9])?\\.)+[a-z0-9](?:[a-z0-9-]*[a-z0-9])?", message="Invalid email")//if the field contains email address consider using this annotation to enforce field validation
    @Basic(optional = false)
    @NotNull
    @Size(min = 1, max = 50)
    @Column(name = "email")
    private String email;
    @Column(table = "breweries_geocode")
    private float latitude;
    @Column(table = "breweries_geocode")
    private float longitude;

    public float getLatitude() {
        return latitude;
    }

    public void setLatitude(float latitude) {
        this.latitude = latitude;
    }

    public float getLongitude() {
        return longitude;
    }

    public void setLongitude(float longitude) {
        this.longitude = longitude;
    }

    public Breweries() {
    }

    public Breweries(Integer id) {
        this.id = id;
    }

    public Breweries(Integer id, String name, String address1, String address2, String city, String state, String code, String country, String phone, String website, String image, String description, int addUser, Date lastMod, double creditLimit, String email) {
        this.id = id;
        this.name = name;
        this.address1 = address1;
        this.address2 = address2;
        this.city = city;
        this.state = state;
        this.code = code;
        this.country = country;
        this.phone = phone;
        this.website = website;
        this.image = image;
        this.description = description;
        this.addUser = addUser;
        this.lastMod = lastMod;
        this.creditLimit = creditLimit;
        this.email = email;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getAddress1() {
        return address1;
    }

    public void setAddress1(String address1) {
        this.address1 = address1;
    }

    public String getAddress2() {
        return address2;
    }

    public void setAddress2(String address2) {
        this.address2 = address2;
    }

    public String getCity() {
        return city;
    }

    public void setCity(String city) {
        this.city = city;
    }

    public String getState() {
        return state;
    }

    public void setState(String state) {
        this.state = state;
    }

    public String getCode() {
        return code;
    }

    public void setCode(String code) {
        this.code = code;
    }

    public String getCountry() {
        return country;
    }

    public void setCountry(String country) {
        this.country = country;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getWebsite() {
        return website;
    }

    public void setWebsite(String website) {
        this.website = website;
    }

    public String getImage() {
        return image;
    }

    public void setImage(String image) {
        this.image = image;
    }

    public String getDescription() {
        return description;
    }

    public void setDescription(String description) {
        this.description = description;
    }

    public int getAddUser() {
        return addUser;
    }

    public void setAddUser(int addUser) {
        this.addUser = addUser;
    }

    public Date getLastMod() {
        return lastMod;
    }

    public void setLastMod(Date lastMod) {
        this.lastMod = lastMod;
    }

    public double getCreditLimit() {
        return creditLimit;
    }

    public void setCreditLimit(double creditLimit) {
        this.creditLimit = creditLimit;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    @Override
    public int hashCode() {
        int hash = 0;
        hash += (id != null ? id.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 Breweries)) {
            return false;
        }
        Breweries other = (Breweries) object;
        if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
            return false;
        }
        return true;
    }

    @Override
    public String toString() {
        return "lit.sd4.model.Breweries[ id=" + id + " ]";
    }

}

BreweriesGeocode 的代码是

    @Entity
@Table(name = "breweries_geocode")
@XmlRootElement
@NamedQueries({
    @NamedQuery(name = "BreweriesGeocode.findAll", query = "SELECT b FROM BreweriesGeocode b"),
    @NamedQuery(name = "BreweriesGeocode.findById", query = "SELECT b FROM BreweriesGeocode b WHERE b.id = :id"),
    @NamedQuery(name = "BreweriesGeocode.findByBreweryId", query = "SELECT b FROM BreweriesGeocode b WHERE b.breweryId = :breweryId"),
    @NamedQuery(name = "BreweriesGeocode.findByLatitude", query = "SELECT b FROM BreweriesGeocode b WHERE b.latitude = :latitude"),
    @NamedQuery(name = "BreweriesGeocode.findByLongitude", query = "SELECT b FROM BreweriesGeocode b WHERE b.longitude = :longitude")})
public class BreweriesGeocode implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id")
    private Integer id;
    @Basic(optional = false)
    @NotNull
    @Column(name = "brewery_id")
    private int breweryId;
    @Basic(optional = false)
    @NotNull
    @Column(name = "latitude")
    private float latitude;
    @Basic(optional = false)
    @NotNull
    @Column(name = "longitude")
    private float longitude;

    public BreweriesGeocode() {
    }

    public BreweriesGeocode(Integer id) {
        this.id = id;
    }

    public BreweriesGeocode(Integer id, int breweryId, float latitude, float longitude) {
        this.id = id;
        this.breweryId = breweryId;
        this.latitude = latitude;
        this.longitude = longitude;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public int getBreweryId() {
        return breweryId;
    }

    public void setBreweryId(int breweryId) {
        this.breweryId = breweryId;
    }

    public float getLatitude() {
        return latitude;
    }

    public void setLatitude(float latitude) {
        this.latitude = latitude;
    }

    public float getLongitude() {
        return longitude;
    }
public void setLongitude(float longitude) {
    this.longitude = longitude;
}

@Override
public int hashCode() {
    int hash = 0;
    hash += (id != null ? id.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 BreweriesGeocode)) {
        return false;
    }
    BreweriesGeocode other = (BreweriesGeocode) object;
    if ((this.id == null && other.id != null) || (this.id != null && !this.id.equals(other.id))) {
        return false;
    }
    return true;
}

Answer 1

在您的第一个类 Breweries 中，您已经定义了一个辅助表。

@Entity
@Table(name = "breweries")
  @SecondaryTable(name = "breweries_geocode")
public class Breweries { ... }

然后在类里面您将声明某些字段将存储到辅助表中，如以下几行所示:

@Column(table = "breweries_geocode")
private float latitude;
@Column(table = "breweries_geocode")
private float longitude;

但是您声明另一个类 BreweriesGeocode 也作为与表关联的实体:

@Entity
@Table(name = "breweries_geocode")
public class BreweriesGeocode { ... }

通过这样做，EntityManager 和 JPA2 实现将假设有两个非常不同的实体。因此，调用第一个 persist() 将会在 breweries_geocode 表中生成一条记录，第二个也会将一个(全新)实体保存到同一个表中。

我认为这里很好地解释了一个有效的简单示例:JPA SecondaryTable Annotation为了使其更好，您可以首先从其他类中删除 @Entity 注释或将其用作委托(delegate)。您还可以告诉 EntityManager(但它是一个不同的主题)检索先前处理的实体并更新其状态(基于上下文的一些缓存等)。在最新的情况下，它会识别出它是相同的实体，并且不会保留新的实体，而只是更新它。